surveying equipment

Abstract

The invention relates to a surveying apparatus comprising a range imaging sensor and a settable target illuminator to provide area illumination in different illumination states. The invention relates to a surveying apparatus (1) embodied as a total station or total position system, wherein the surveying apparatus (1) comprises a laser distance measuring module configured to generate a distance measuring beam for a single point measurement to determine a distance to a measurement point aimed at by the distance measuring beam. Furthermore, the surveying apparatus (1) comprises a range imaging module with a switchable target illuminator (10) to provide different distance dependent illumination states (12, 14, 15) of an area illumination comprising a wide illumination state and a narrow illumination state.

Description

Technical Field

[0001] This invention relates to a surveying apparatus specifically implemented as a total position system (TPS) or a total station. Such a surveying apparatus is used in various fields where it is necessary to measure the coordinated positions of spatial points or determine geometric relationships, for example, in construction sites, industrial facilities, or in land surveying. Background Technology

[0002] For example, a total station is used to measure the coordinates of a spatial point relative to the total station, such as to generate a set of spatial measurement points for a reference common coordinate system. Another common function of a total station involves stake-out points in the environment, for example, where a first person aligns the total station's telescope target axis to match a calculated posture, and a second person carrying the stake-out equipment (e.g., which includes a retroreflector) is guided toward an aiming point defined by the total station's target axis and a calculated distance from the total station.

[0003] As an example, for coordinated measurements, modern total stations are typically precisely horizontally aligned, for example, by means of a bubble level or a tilt sensor, where the coordinates of the measurement point are obtained by simultaneously aiming at the point using an aiming component (often called a "telescope") by measuring distance, horizontal angle, and vertical angle. The aiming component provides the transmission and reception of a laser beam, where the distance in the direction of the laser beam is measured by an electro-optic distance measuring device. Electro-optic distance measurement is performed by emitting a laser beam to provide pulse-time-of-flight (TOF) measurement methods, phase-shift measurement methods, or interferometric methods. The orientation of the aiming component is determined by the total station's angle measuring device (e.g., a goniometer including an angle encoder such as an absolute or incremental rotary encoder).

[0004] Once the surveying equipment is set up in a specific location, it typically measures multiple spatial points so that they can be referenced relative to the surveying equipment (e.g., in a fairly intuitive way) a common coordinate system.

[0005] Typically, surveying projects require repositioning the surveying equipment, for example, because a line of sight to all relevant measurement points cannot be provided at once. The surveying equipment must then be repositioned and reconfigured to measure all relevant points. Measurement points taken from different locations on the surveying equipment (coordinated spatial points) must be correlated with each other using a process commonly referred to as referencing, point set registration, or scan matching. This can be done, for example, based solely on data from 3D coordinate points measured using electronic distance measurements included in the surveying equipment. As an example, known methods for referencing total station data at different measurement locations involve using a polygon course, or so-called free-station method.

[0006] Today, there is a growing demand for total stations capable of recording 3D point clouds as quickly and accurately as possible, for example, to produce precise digitizations of objects with natural and man-made surfaces. These total stations are often referred to as "scanning total stations" or "robotic total stations." Compared to conventional laser scanners, known scanning total stations are typically almost 1000 times slower in providing 3D point clouds.

[0007] One reason for the slower scanning speed is the accuracy requirements that limit the general setup of the total station, for example, to provide coordinate measurements with geodetic accuracy. The telescope unit is typically mounted with high precision to a base and (e.g., fork-shaped) support, where high-precision angle sensors are used to provide high pointing stability. This often results in a rather heavy and bulky construction that contradicts the need for rapid scanning movement. Summary of the Invention

[0008] Therefore, the purpose of this invention is to provide a surveying device specifically implemented as a total positioning system or a total station, which overcomes the shortcomings of the prior art in providing 3D point clouds.

[0009] The specific purpose is to provide a surveying device, specifically implemented as a total positioning system or total station, that provides faster acquisition of 3D point clouds.

[0010] Another objective is to provide an improved surveying device, specifically implemented as a total positioning system or total station, that offers easier handling, requiring less expertise and training to operate the surveying device to obtain 3D point clouds.

[0011] This invention relates to a surveying device, specifically implemented as a total positioning system or total station, comprising: a base and an aiming component rotatable relative to the base about two alignment axes; and an angle determining device configured to generate angle data providing the orientation of the aiming component relative to the two alignment axes. The surveying device also includes a laser distance measurement module configured to generate a distance measuring beam for single-point measurement to determine the distance to a measurement point aimed at by the distance measuring beam, wherein the distance measuring beam is emitted from the aiming component via a beam exit.

[0012] Typically, single-point measurements performed by a laser distance measurement module are associated with high-precision pointing information provided by an angle determination device. This allows the 3D coordinates of the targeted measurement point to be determined with geodetic accuracy. For example, the distance measurement beam is a directional collimated laser beam that allows for the measurement of a point on an object with optimal (maximum) lateral spatial resolution (a small beam coverage area on the object) while providing sufficiently high signal return to ensure high distance measurement accuracy (high signal-to-noise ratio). In other words, single-point measurement is the measurement of a single point on the object to be measured, where both lateral spatial resolution and distance measurement accuracy are provided as precisely as possible for the object surface hit in a one-dimensional aiming direction.

[0013] The surveying equipment further includes a range imaging module comprising a target illuminator unit disposed at the aiming component and a fixed imaging optical path disposed at the aiming component to image the radiation emitted by the target illuminator unit returning from the environment to the range imaging sensor (so-called the RIM sensor). The range imaging sensor is configured to provide depth image generation using area illumination returned from the environment by the target illuminator, wherein the depth image is generated from angle data of a reference angle determination device. Therefore, the precise orientation of the range imaging sensor during depth image acquisition can be associated with each depth image, and the surveying equipment is configured to use a reference to the angle data of the angle determination device to provide a transformation of coordinate information from multiple depth images acquired with different orientations for the aiming component to a common coordinate system.

[0014] As an example, known RIM sensors (also known as 3D imaging sensors or TOF sensors) are based on silicon-based CMOS technology. Current trends include increased pixel counts, smaller pixel pitch, and improved sensitivity in the near-infrared wavelength region (e.g., 905 nm). High-sensitivity RIM sensors are typically configured as back-illuminated sensors because this generally provides higher quantum efficiency and a higher fill factor compared to front-illuminated designs. Recently, further steps have been taken to increase sensitivity, particularly at longer wavelengths (such as 940 nm), through improved single-photon avalanche diode (SPAD) designs. These new CMOS sensors offer greater versatility for RIM cameras, such as for high-resolution point cloud recording at eye-safe wavelengths.

[0015] The target illuminator is configured to provide area illumination under different illumination states, including a wide illumination state and a narrow illumination state, wherein the wide illumination state provides illumination of a larger volume compared to the narrow illumination state.

[0016] For example, the target illuminator provides different light cone shapes to provide wide and narrow lighting states, wherein, for the same device-object distance, the coverage area of ​​the light cone associated with the wide lighting state is larger than the coverage area of ​​the light cone associated with the narrow lighting state.

[0017] The surveying equipment is configured to provide an allocation of sub-regions within the area to be measured based on the distance distribution of measurement points in the area to be measured. Each sub-region is associated with the orientation of an aiming component about one or both of two alignment axes and with one of different illumination states. The allocation of sub-regions within the area to be measured, along with the associated orientation and illumination information, is then used to provide the surveying equipment in a manner that allows it to automatically execute a scanning sequence for measuring the area to be measured. The scanning sequence involves sequentially setting each of the orientations of the aiming component associated with a sub-region and generating a depth image for each of the orientations of the aiming component using the associated illumination states provided by the allocation of sub-regions within the area to be measured.

[0018] Geodetic or industrial coordinate surveying typically requires absolute measurement accuracy within millimeter or sub-millimeter ranges, necessitating stable surveying equipment unaffected by internal or external interference. Typically, Time-of-Flight (ToF) cameras operate within wavelength ranges susceptible to interference from sunlight and temperature variations. Therefore, to achieve sufficient distance measurement accuracy, the available distance-measuring imaging sensor (also known as a ToF camera) generally needs a sufficiently high return signal to allow for the desired signal-to-noise ratio level.

[0019] One way to address these issues with ToF cameras is to provide different transmit powers and / or different modulation frequencies for the area illumination. However, simply increasing the transmit power and / or applying a high transmit frequency may still be insufficient and / or lead to technical complexity.

[0020] Using different illumination states (e.g., switching between light cones with different solid angles used to provide area illumination) has the advantage of providing a distance-related trade-off between better focused transmission power and thus increased irradiance at maximum field of view. Combined with precise angular information from the angle determination device, the surveying equipment is extended to instruments that produce high measurement and point accuracy and provide accelerated scanning capabilities.

[0021] In one embodiment, the surveying device is configured to provide a display of a representation of the surrounding environment and to respond to user-input queries to select an area to be measured.

[0022] As an example, surveying equipment can be used to provide scanning of large scenes up to the entire dome, where multiple depth images are combined to form a large-scale single-point cloud with accuracy in angular seconds. After manually or automatically defining the area to be measured, sub-regions within the area to be measured, along with associated orientation and lighting information, can be provided manually, semi-automatically, or fully automatically.

[0023] In one embodiment, the surveying device is configured to provide display and editing functions, including: displaying a representation of the area to be measured, indicating the allocation of sub-regions within the area to be measured, and querying user input to provide an adjusted allocation of sub-regions within the area to be measured, wherein a scan sequence is performed based on the adjusted allocation.

[0024] Therefore, in manual mode, the user aligns the surveying device with the scene and uses the aiming component and laser distance measurement module to estimate or measure selected distances within the scene. Based on these distances, the surveying device can then automatically display the acquired sub-regions to the user, such as sub-regions with associated additional lighting information, allowing the user to refine and edit the selection of suggested sub-regions using an interface (e.g., a graphical interface).

[0025] In a more automated mode, for example, the survey is configured to generate initial depth images or sequences of initial depth images using a wide illumination state, with the aiming component in different orientations about one or both of the two alignment axes. The initial depth images or sequences of initial depth images are then used to determine the distance distribution used to provide the allocation of sub-regions within the area to be measured.

[0026] In another embodiment, the surveying equipment is configured to access a digital 3D model of the environment and use the digital 3D model to determine the distance distribution for providing the allocation of sub-regions within the area to be measured.

[0027] For example, the surveying equipment is loaded with a digital terrain model (DTM) or digital surface model (DSM), and the corner points of the window of the scene to be measured are manually set in the upper left and lower right corners of the surveying equipment's display. Using the DTM or DSM, the surveying equipment knows the approximate distance within the field of view to be measured, and the ranging imaging module uses this information to determine the sub-regions assigned to the distances and the associated lighting conditions. The surveying equipment can then automatically control the necessary angular alignment of the aiming component, allowing the ranging imaging module to perform a scan sequence to provide a merged point cloud of the entire scene.

[0028] In another embodiment, the surveying device is configured to provide sub-region allocation within the area to be measured by further combining a scanning pattern generated by a moving aiming component and distance measurement using a laser distance measurement module. Here, the area to be measured is initially segmented into regions corresponding to one or more illuminations performed by a wide illumination state, wherein scanning of the distance measurement beam is used to refine the initial wide-angle segmentation.

[0029] One or more wide-angle areas are provided for the area to be measured, wherein each of the one or more wide-angle areas corresponds to an illumination area illuminated by a wide illumination state for the associated orientation of the aiming component. A single wide-angle area or a combination of wide-angle areas provides complete coverage of the area to be measured. The surveying device performs a scanning mode by moving the aiming component about one or both of two alignment axes and determining distances using a distance measuring beam from a laser distance measuring module in different orientations of the aiming component, wherein distance determination by the distance measuring beam is provided in each of the one or more wide-angle areas. Then, the wide-angle areas are divided using the distances determined by the scanning mode, wherein at least one wide-angle area is divided into small-angle areas, and each small-angle area corresponds to an illumination area provided by the associated orientation of the aiming component and by illumination in different illumination states that provide illumination of a smaller volume compared to the wide illumination state.

[0030] In another embodiment, the different lighting states further include a medium lighting state, which provides a larger volume of illumination compared to the narrow lighting state and a smaller volume of illumination compared to the wide lighting state.

[0031] In another embodiment, the ranging imaging sensor is configured to provide settings for activity detection zones of different sizes, and the surveying device is configured to coordinate the settings for activity detection zones of different sizes with settings for different illumination states of the target illuminator, for example, by taking into account the distance determined by the laser distance measurement module or the ranging imaging module.

[0032] In another embodiment, the surveying equipment is configured to operate within three defined distance measurement ranges: a short-range measurement range, a medium-range measurement range, and a long-range measurement range. The short-range measurement range covers distances shorter than the medium-range and long-range measurement ranges. The medium-range measurement range covers distances longer than the short-range measurement range and shorter than the long-range measurement range. The long-range measurement range covers distances longer than the short-range and medium-range measurement ranges.

[0033] The sub-region allocation includes: assigning sub-regions associated with narrow lighting conditions to the medium-distance measurement range; assigning sub-regions associated with wide lighting conditions to the short-distance measurement range; and assigning additional sub-regions to the long-distance measurement range.

[0034] The scanning sequence includes switching between a laser distance measurement module and a ranging imaging module to: use the laser distance measurement module and the distance measurement beam to determine distance in the additional sub-regions allocated to the long-distance measurement range; use the ranging imaging module to acquire a depth image using the narrow illumination state to determine distance in the sub-regions allocated to the medium-distance measurement range; and use the ranging imaging module to acquire a depth image using the wide illumination state to determine distance in the sub-regions allocated to the short-distance measurement range.

[0035] In another embodiment, the laser distance measurement module is configured to generate a distance measurement beam with a center wavelength within the visual wavelength range, and the target illuminator is configured to generate area illumination with radiation within the near-infrared wavelength range. For example, depending on the application area of ​​the surveying instrument, the area illumination can have different wavelengths, such as 850 nm, 905 nm, or 1064 nm. Interference with sunlight is less of a problem than for indoor use. Therefore, 905 nm may be a beneficial wavelength for indoor applications, but not for outdoor applications.

[0036] As an example, the center wavelength of the distance measurement beam is in the range of 620 nm to 700 nm, the radiation of the area illumination is in the wavelength range of 930 nm to 950 nm, and the fixed imaging optical path includes an optical bandpass filter for blocking radiation outside the wavelength range of the area illumination.

[0037] For example, the visible distance measurement beam of the laser distance measurement module is preferably used for long-distance measurements, while also functioning as a pointer. The high atmospheric transmittance in the visible spectrum is advantageous for long measurement distances. The 940 nm transmitted radiation of the ranging imaging module is intended for short distances. Since atmospheric transmittance is low at 940 nm, the influence of sunlight is reduced or virtually eliminated, providing improved distance measurement noise and thus improved distance measurement accuracy. Sunlight beyond 930 nm and 950 nm can be blocked by means of optical interferometry or bandpass filters, ensuring that only radiation from the target illuminator impacts the ranging imaging sensor. As a result, sensor saturation is avoided, and the detection signal remains within the linear detection range.

[0038] In another embodiment, different lighting conditions have different transmission power and / or different transmission frequencies.

[0039] In another embodiment, the aiming component includes a receiving aperture for a fixed imaging optical path and different transmitting apertures for providing different illumination states, wherein the different transmitting apertures are arranged in a point-symmetric manner around the receiving aperture. For example, the target illuminator includes three (especially six) separate VCSEL transmitting apertures arranged in a circular manner in a point-symmetric manner around the receiving aperture.

[0040] In another implementation, the target illuminator includes a radiation source and is configured to adapt to the diffusion behavior of the radiation source to provide switching between different lighting states.

[0041] In another embodiment, the surveying device is configured to automatically identify a reference point within a first depth image generated by the ranging imaging module in a first orientation of the aiming member, using coordinates of a reference point in the environment determined by the laser distance measurement module. The surveying device is further configured to automatically pivot the aiming member about one or both of two alignment axes to move the position of the reference point within the field of view of the ranging imaging sensor, and to identify the reference point within a second depth image generated in a second orientation of the aiming member different from the first orientation of the aiming member. Then, field-of-view correlation correction parameters for determining coordinates from the depth image of the ranging imaging unit are determined using the coordinates of the reference point determined by the laser distance measurement module and the coordinates of the reference point determined from the first and second depth images.

[0042] In another embodiment, the surveying device includes at least one imaging sensor for capturing a 2D image of the environment, wherein the surveying device is configured to provide a transformation of coordinate information from the 2D image to a common coordinate system. For example, the surveying device is configured to capture a 2D image to provide coloring of a point cloud generated using a laser distance measurement module.

[0043] As an example, at least one imaging sensor is specifically implemented as a CMOS-based image sensor, for example, to capture a 2D image of a measurement scene for documentation or to colorize scanned 3D data. Typically, such an image sensor is well calibrated relative to the instrument coordinate system associated with the 3D measurement performed by the laser distance measurement module and therefore to the field of view associated with the 2D image sensor, and in particular, the pixel coordinates of the 2D image sensor are generally known to have high accuracy.

[0044] According to this embodiment, the surveying device is further configured to analyze 2D images to determine coordinate parameters of comparison points (e.g., those associated with edges or sides) in the environment imaged by the 2D images, and (e.g., automatically) identify comparison points within a depth image generated by the ranging imaging unit. As an example, at least one sensor is arranged at an aiming component and generates a corresponding depth image in the same orientation as used to capture the 2D image. The coordinate parameters and the coordinates of the comparison points determined from the corresponding depth image are then used to determine field-of-view (FOV) related correction parameters for determining coordinates from the depth image of the ranging imaging unit. For example, the FVO of this embodiment and the FVO of the embodiments described above are combined to provide improved field-of-view correction. Alternatively or additionally, the two correction parameters address different segments or problem areas within the field of view of the ranging imaging sensor.

[0045] In another embodiment, the ranging imaging module is configured to set the modulation frequency on the ranging imaging sensor and the trigger frequency for triggering the emission of area illumination based on different lighting conditions and, in particular, based on the pivoting speed of the aiming component about one or both of the two alignment axes. Attached Figure Description

[0046] The following description or explanation, by way of example only, refers to the working examples schematically shown in the accompanying drawings to illustrate different aspects of the surveying apparatus according to the invention. Identical elements are labeled with the same reference numerals in the drawings. The described embodiments are generally not shown to scale and should not be construed as limiting the invention. Specifically,

[0047] Figure 1 This is an exemplary embodiment of the surveying equipment according to the present invention, wherein the surveying equipment includes an electronic laser distance measurement module and a distance measurement imaging module;

[0048] Figure 2 The cross-sections of different areas illuminated by the target illuminator are schematically depicted (at the same distance).

[0049] Figure 3 This is an exemplary application of a surveying device with switchable target lighting for measuring streets;

[0050] Figure 4 This is another exemplary application of the surveying equipment of the present invention, wherein a scene is measured with sufficient point density and in the shortest possible time.

[0051] Figure 5 A so-called manual measurement mode is schematically depicted for providing the allocation of sub-regions within a region of measurement based on the distance distribution of measurement points in the region of measurement.

[0052] Figure 6 A so-called semi-automatic measurement mode is schematically depicted for providing the allocation of sub-regions within the area to be measured based on the distance distribution of measurement points in the area to be measured;

[0053] Figure 7 A so-called fully automated measurement mode is schematically depicted for providing the allocation of sub-regions within a region of measurement based on the distance distribution of measurement points in the region to be measured;

[0054] Figure 8 The calibration of the field-of-view correlation correction parameters used to determine coordinates from the depth image of the ranging imaging unit is schematically depicted;

[0055] Figure 9 An embodiment of the aiming component is schematically depicted, wherein the emission aperture of the target illuminator is arranged symmetrically around the objective lens point of the imaging optics of the ranging imaging module;

[0056] Figure 10 Another implementation of the transmitting unit of the ranging imaging module is schematically depicted, wherein six separate laser apertures are arranged in a circular manner in a point-symmetric manner around the objective lens of the imaging optics of the ranging imaging module.

[0057] Figure 11 An implementation method for achieving subpixel resolution for a ranging imaging module by utilizing a precise angle determination system of a surveying device is illustrated. Detailed Implementation

[0058] Figure 1 The basic structural elements of a surveying device 1, specifically implemented as a total positioning system (TPS) or total station, are exemplified. The surveying device includes a base 2, which can be mounted on a holding device, for example, in the form of a tripod bracket (not shown). A support structure 3 is mounted on the base 2 such that the support structure 3 can rotate about a vertical axis 4, wherein the support structure 3 holds an aiming component 5, which can rotate about a horizontal axis 6. Both the support structure 3 and the aiming component 5 can be rotated electrically, for example by means of an electric shaft 7, wherein the orientation of the support structure 3 and the aiming component 5 can be determined by a corresponding angle encoder (not shown). Optionally, a user interface, such as a keyboard-display unit 34, is attached to the surveying device 1, for example, to the support structure 3. Alternatively or additionally, the surveying device 1 may be equipped with a wireless interface to a handheld control unit, for example, the control unit including a graphical user interface.

[0059] The aiming component 5 is configured to emit a range-measuring beam toward the target object along the aiming axis 8. As an example, the objective lens 9 has the same transmission and reception channels for the range-measuring beam. The aiming component 5 houses an electro-optical rangefinder configured to determine the distance to a single target point aimed at by the aiming axis 8 based on at least a portion of the range-measuring beam returning from the target. As an example, a portion of the electro-optical rangefinder (e.g., the beam source) may also be arranged in the support structure 3, wherein an optical fiber-based waveguide system connects the elements integrated in the support structure 3 to the aiming component 5 via a shaft 7.

[0060] The surveying equipment 1 further includes a ranging imaging module disposed at the aiming component 5, for example, wherein the ranging imaging module is mounted in the cover of the aiming component 5. Typically, the ranging imaging module (also known as a 3D camera measurement system or a 3D TOF camera (TOF: Time of Flight)) comprises three sub-units: a transmission module 10, also known as a target illuminator; a ranging imaging sensor (RIM sensor); and an imaging optics device 11; and a timing module. The ranging imaging module can be controlled by the central processing unit of the surveying equipment.

[0061] As an example, known 3D Time-of-Flight (TOF) cameras are based on the phase-shift measurement principle, or the so-called pulse evaluation principle, where the transmission and reception times of the transmitted and received pulses are determined. The phase-shift principle is also known as indirect time-of-flight (i-TOF), and the pulse or waveform principle is also known as direct time-of-flight (d-TOF). For example, regarding the modulation of the transmitted laser signal to achieve high longitudinal resolution (e.g., 1 mm), i-TOF technology has a laser modulation scheme in which the laser emits a rectangular wave from 40 MHz to over 200 MHz. In the case of d-TOF sensors, the laser typically emits pulses or pulse sequences with short durations and pulse widths, typically 0.2 ns but not longer than 3 ns.

[0062] According to one aspect of the invention, the target illuminator 10 is configured to provide area illumination under different lighting conditions, wherein the coverage area of ​​the scene area illumination is switched for different distance ranges, for example, wherein the emission characteristics of the transmitter unit are adjusted so that the scene area is illuminated differently, for example, wherein radiation is emitted at different solid angles.

[0063] As an example, the distance measuring beam is emitted at a center wavelength of 658 nm, and the area illumination of the target illuminator 10 is emitted at a wavelength of 940 nm. The visible distance measuring beam of the coaxial electronic distance measuring module measures both short and long distances, and also functions as a pointer due to its coaxial arrangement with the target axis 8. Infrared transmitted radiation is designed for the range imaging sensor and is measured only at short or medium distances.

[0064] Figure 2 The diagram schematically depicts cross-sections (at the same distance) of illumination from different areas produced by the target illuminator 10. The target illuminator provides what is known as the instantaneous field of view (i-FOV). For example, the i-FOV is set by the user via configuration before the actual measurement activity or measurement series.

[0065] From the user's perspective, a crucial criterion for selecting the illumination field of view of a target illuminator is the measurement distance. At long distances, it may be preferable to concentrate the entire transmission power of the transmitting unit on the smallest possible solid angle to maintain sufficient irradiance on the target object's surface. However, a small illumination field of view may require multiple pivoting of the surveying equipment to capture multiple images of the scene to be stitched together.

[0066] As an example, when i-FOV 12 is selected, the following modules are switched: the beam angle of the target illuminator is changed; the transmit power is reduced, increased, or kept constant; the depth image data reduction pipeline is adapted to i-FOV; the setting of the active detection zone is adapted to i-FOV; the trigger and modulation frequencies on the RIM sensor and transmitter unit are set according to the selected i-FOV; and the internal electronic measurement process and data evaluation parameters are changed.

[0067] Imaging optics 10 in front of the RIM sensor Figure 1 This ensures that the internal RIM camera calibration of the survey equipment's coordinate system remains unchanged. This allows for arcsecond-level directional accuracy for coordinate measurements via the distance measurement module and the ranging imaging module.

[0068] For example, the target illuminator is configured to provide the following: a first illumination state 12 providing i-FOV corresponding to the full field of view 13 of the ranging imaging sensor; a second illumination state 14 providing i-FOV corresponding to one-quarter of the field of view 13 of the ranging imaging sensor; and a third illumination state 15 providing i-FOV corresponding to one-sixteenth of the field of view 13 of the ranging imaging sensor. The first illumination state is used to measure short distances, for example, 0 m to 30 m; the second illumination state is used to measure medium distances, for example, 5 m to 60 m; and the third illumination state is used to measure long distances, for example, 10 m to 100 m. In addition, a laser distance measurement module (laser distance measurement beam) of the surveying equipment is used.

[0069] In addition to different spatial radiation beams, the four settings (first illumination state, second illumination state, third illumination state, and the use of a laser distance measurement module) may also include different transmission powers and transmission durations. The transmission power and transmission duration of the settings are preferably designed to ensure that the radiation is safe for the eyes.

[0070] The switchable solid angle of the target illuminator of the 3D camera has the following advantages: high-quality measurement data is generated at greater distances due to better focused transmission power and thus increased irradiance in the case of a reduced field of view.

[0071] For example, the target illuminator cone can be set using a switchable hologram, by activating the field of view (FOV) of an assigned laser array, or by an addressable laser array. Addressable laser arrays, for instance, offer the advantage of allowing different target illuminator cones to be switched purely electronically, where radiation is emitted toward the target via a single common optics device.

[0072] In the second illumination state 14 and the third illumination state 15, only a portion of the receiver's field of view 13 is illuminated. To improve the signal-to-noise ratio, only this portion of the area can be read out and converted into a common, merged point cloud of the digital environment.

[0073] Figure 3 An exemplary application of surveying equipment 1 with a switchable target illuminator is shown. Here, a street with adjacent artifacts is being measured. The figure illustrates a reference... Figure 2 The coverage areas of the i-FOV for the first illumination state 12 and the third illumination state 15 are explained. For example, in the case of the first illumination state 12, the road can be measured from approximately 10 m to 30 m, where, due to insufficient sensitivity, larger distances cannot be determined sufficiently accurately using the first illumination state 12. Therefore, the second illumination state (not shown) is used for medium distances (e.g., 30 m to 60 m), and the third illumination state 15 is used for long distances (e.g., distances between 60 m and 100 m).

[0074] Alternatively, the third illumination state 15 can be used to measure and digitize the entire length of the road. However, due to the limited i-FOV of the third illumination state 15, some recording is required at close range, which is performed by rotating the aiming part of the surveying equipment.

[0075] Figure 4 Another exemplary application of the surveying device of the present invention is shown, wherein a scene is measured with sufficient point density (e.g., without many missing points) and in the shortest possible time. Here, the scene includes buildings, wherein, from the perspective of the location of the surveying device, it is required that the measurements differ between at least three different measurement ranges of the ranging imaging module.

[0076] For example, the user defines the area to be measured 16 via the graphical user interface of the surveying equipment. Here, for simplicity, the area to be measured 16 corresponds to the maximum i-FOV provided by the ranging imaging module. The two left quadrants 17 of the area to be measured 16 correspond to near-range measurements, which are well-suited for ranging imaging measurements using the maximum i-FOV. The upper right quadrant 18 of the area to be measured 16 includes a portion of a building, which should be measured by a different lighting condition (e.g., a lighting condition providing one-quarter of the full i-FOV), because measurements using the full i-FOV would not provide sufficient sensitivity (the distance to be measured in the scene is longer than the distance that will be achieved by the ranging imaging sensor in that i-FOV setting). The lower right quadrant includes a portion of a building on the left that can be measured using the lighting condition used for the upper right quadrant 18. However, the right portion 19 includes a more distant portion of the building that should be measured by a more concentrated lighting condition (e.g., a lighting condition providing one-eighth of the full i-FOV).

[0077] As an example, Figure 4 The scenarios shown can be measured manually, semi-automatically, or fully automatically, such as... Figures 5 to 7 This is a schematic depiction. The surveying equipment is set up and referenced to an external (e.g., global) coordinate system. This is accomplished using control points or reference points within the building area.

[0078] The scene to be measured is recorded, for example, by the maximum i-FOV, but within that i-FOV, the ranging imaging camera is not sensitive enough to measure all parts of the building. For example, the sensitivity of the ranging imaging camera is affected by the selected i-FOV on the transmitter side and the exposure or accumulation time on the receiver side. The signal accumulation time for each pixel or sub-pixel is determined by setting the frame rate. The target illuminator emits shorter or longer burst sequences, depending on the length of the accumulation time set on the sensor side. The frame rate set by the user or the specified maximum image acquisition time informs the camera whether only one image or several images are needed for each target scene.

[0079] exist Figure 5 In the manual measurement mode shown, the user aligns the surveying equipment with the scene. The user uses an internal distance measurement module to estimate or measure selected distances within the scene using a distance measurement beam emitted along the target axis. Based on these distances, the instrument automatically obtains suggested selections of different i-FOVs for measuring the scene, which is presented, for example, on the handheld control unit or keypad display unit 34 of the surveying equipment. Figure 1 The graphical user interface is displayed on the screen. Users can then edit or redefine the suggested i-FOV selection.

[0080] In the example shown, seven i-FOVs and corresponding aiming directions are selected for the aiming component. In the lower right quadrant, the suggested scan sequence includes four measurement steps (four aiming directions) using the minimum available i-FOV. The scan sequence then continues to measure the other three quadrants using an i-FOV four times larger than the minimum i-FOV.

[0081] After the user has edited or accepted the suggested scan sequence, the surveying equipment begins the measurement and aligns its target axis, thus aligning the i-FOV of the ranging imaging unit in the direction given by the seven measurement steps. At each alignment, the ranging imaging unit creates 3D coordinates of the scene using the specified i-FOV.

[0082] As an example, the ranging imaging unit can acquire HDR-like (HDR: High Dynamic Range) depth images in any orientation based on a set maximum image acquisition time. Longer image acquisition times can accumulate over a considerable period, which (slightly) increases the range of dark targets and reduces distance jitter. Therefore, the illumination / pulse burst on-time and laser burst duration are set on the transmitter side corresponding to each modulation frequency.

[0083] exist Figure 6 In the depicted semi-automatic surveying mode, the surveying equipment can access a digital terrain model (DTM) or a digital surface model (DSM). For example, the corner points of the area to be measured 16 can be manually set by indicating the upper left and lower right corners on the surveying equipment's display. By using the digital terrain model, the surveying equipment knows the approximate distances within the area to be measured 16. This information is then used to automatically determine the i-FOV based on these approximate distances.

[0084] In the example shown, six measurement steps are identified that correspond to six pointing directions of the aiming component. The lower right quadrant is measured by three different pointing directions and two different i-FOVs (the right part of the quadrant is measured using half the size of the i-FOV of the left part of the quadrant). Again, the other quadrants corresponding to the closer areas of the building are measured using a larger i-FOV.

[0085] exist Figure 7In the fully automatic measurement mode shown, the user manually defines the corner points of the area 16 to be measured, for example, by entering markers on the display of the surveying equipment. In a further step, the scene is divided into regions of maximum i-FOV. In the example shown, the scene roughly corresponds to the size of a single maximum i-FOV. In another step, the surveying equipment moves the aiming component to scan the target axis along a first trajectory 20, wherein distance determination is provided by the distance measuring beam at a defined measurement rate. Since the distances in the lower left quadrant and the two top quadrants correspond to the distance measurement range associated with an i-FOV that is one-quarter of the maximum FOV, the area to be measured is divided into these four quadrants. Furthermore, the surveying equipment has determined that at least a portion of the lower right quadrant can only be measured with a smaller i-FOV. Therefore, the lower right quadrant is further divided into four regions corresponding to the size of the minimum i-FOV.

[0086] Optionally, the surveying equipment is configured to perform a further scan along trajectory 21 within the lower right quadrant to optimize the i-FOV in that quadrant. For example, in such an additional scan, the result is that only the right portion of the bottom quadrant needs to be measured with the minimum i-FOV, while the left portion can be measured using the same i-FOV as the other quadrants used for the region 16 to be measured. Thus, a total of six different pointing directions and two different i-FOVs are identified, with four pointing directions corresponding to the four quadrants of the region 16 to be measured using the medium i-FOV, and two pointing directions corresponding to two different directions in the right portion of the lower right quadrant of the region 16 to be measured using the minimum i-FOV (wherein the measurement results on the right portion of the lower right quadrant measured by the medium i-FOV are replaced by the measurement results generated by using the minimum i-FOV).

[0087] Figure 8 The calibration of the field-of-view correlation correction parameters used to determine coordinates from the depth image of the ranging imaging unit is schematically depicted.

[0088] As an example, initially, the ranging imaging unit is referenced to the local coordinate system of the surveying equipment using factory calibration. Additionally, a field calibration option is provided to the user to further calibrate the ranging imaging unit, for example, to address temperature or orientation-related distortion effects caused by stress on the imaging optics and / or the ranging imaging sensor. This can be accomplished with different distances (longitudinal error) and various target settings for the aiming components (angular errors with different target orientations and sensor torsion or tilt). The calibration and inherent precise orientation of the laser distance measurement module's distance measurement beam are used as a reference. In this way, both the distance offset and the angular orientation offset (optical distortion) used to determine the absolute distance can be determined.

[0089] For example, the user manually aims the laser distance measurement beam at various easily identifiable reference points 22 within the i-FOV 23 to be calibrated. Precise distance measurements using an angle sensor and the laser distance measurement module determine the 3D coordinates of these points with sub-millimeter accuracy. In a subsequent step, the ranging imaging module acquires a depth image, thereby ensuring that the measured reference points 22 are within the i-FOV of the ranging imaging module.

[0090] Alternatively, the identification and assignment of reference point 22 may be performed automatically, for example, through the automatic search function of the survey equipment.

[0091] Alternatively, a single reference point can be used, in which the aiming component is moved to acquire multiple depth images in different orientations, such that a reference point is placed at different locations within different depth images.

[0092] Figure 9 An embodiment of the aiming component 5 is schematically depicted, wherein the emission aperture 24 is symmetrically arranged around the objective lens 25 of the imaging optics of the ranging imaging module, for example, wherein the emission aperture 24 is arranged above the objective lens 9 of the laser distance measurement module of the surveying device.

[0093] For example, distance measurements with high absolute accuracy can be performed by means of transmitting apertures arranged symmetrically with respect to receiving apertures, because the interference caused by parallax between the transmitting and receiving apertures of the ranging imaging module is eliminated (parallax-related distance variations cancel each other out across the entire field of view and in terms of distance).

[0094] Figure 10 Another embodiment of the transmitting unit of the ranging imaging module is schematically depicted, wherein six individual laser apertures (e.g., VSCEL laser diodes or addressable VCSEL arrays) are arranged in a circular manner in a point-symmetric manner around the objective lens 25 of the imaging optics of the ranging imaging module. The six laser apertures are configured such that there are three pairs of laser apertures 26, 27, 28, wherein the apertures of the same pair are arranged opposite to each other, and the apertures of different pairs of apertures produce different light cones, for example, light cones emitting radiation at different light cone angles.

[0095] As an example, the six laser apertures are generated by six individual laser diodes arranged in a circular pattern in a point-symmetric manner around the objective lens 25 of the imaging optics. Alternatively, an addressable VCSEL array is located behind the six apertures. Different light cones of emitted radiation are achieved by activating regions of different sizes on the addressable VCSEL array. For example, all six apertures are addressed using the same mode, so all six apertures produce the same light cone angle. One advantage of distributing the radiated laser power across the six apertures can be seen is the ability to provide high laser power at low laser grades.

[0096] Figure 11 This illustration schematically depicts an implementation method for achieving subpixel resolution for a ranging imaging module using a precise angle determination system of a surveying device. Several depth images are acquired by utilizing a limited rotation of the aiming component within the angular range of the subpixels of the ranging imaging sensor.

[0097] The top of the figure depicts the horizontal and vertical arrangement of measurement points 29 associated with the sensor pixel grid. By introducing a first movement 30 of the aiming component (which introduces a displacement of the initial grid of measurement points with a spacing smaller than that between adjacent pixels), a second depth image is obtained, with measurement point 31 displaced by a subpixel relative to the first measurement point 29. Thus, by combining these two depth images, the scene is acquired at subpixel resolution. The bottom of the figure depicts the result of acquiring depth images using two additional movements 32, 33. Thus, the point spacing is halved, resulting in only four acquisitions. Using the axis and angle system of the surveying equipment, the point density of the surface to be digitized can be increased almost arbitrarily without requiring the ranging imaging sensor to provide a corresponding pixel resolution.

[0098] Therefore, due to the precise angle determination and angle setting devices of the surveying equipment, the surveying equipment can be configured to provide resolution enhancement capabilities, wherein the aiming component automatically pivots about one or both of the two alignment axes within a sub-pixel angular pivot range on the ranging imaging sensor. Then, a combined depth image, acquired in different pivot states of the aiming component about one or both of the two alignment axes, is provided to offer a combined depth image with sub-pixel resolution compared to the inherent pixel resolution provided by the ranging imaging sensor.

[0099] As an example, subpixel acquisition is applied when measuring longer distances because the spatial resolution of the fixed-focal-length receiving optics of the RIM sensor decreases with increasing distance. For instance, when using a VGA-format RIM sensor with 640×460 pixels and an imaging optics producing an i-FOV of 65°×48° as the maximum i-FOV, the spatial resolution of the RIM sensor is 0.1°×0.1° per pixel. This corresponds to a dot pitch of 17 mm at a distance of 10 m and 17 cm at a distance of 100 m. This resolution is sufficient for many construction and surveying applications up to 100 m; however, higher spatial resolution may be required for detailed surface recording, especially at distances greater than 50 m. Figure 11 As shown at the top, by acquiring a second depth image in which measurement point 31 has moved by a subpixel relative to the first measurement point 29, the resolution of the point cloud is doubled, and the angular resolution is increased by the square root of 2. At 100 m, the angular spacing of the points is reduced to 12 cm, particularly thanks to the precise angle determination and angle setting methods of the surveying equipment.

[0100] Although the invention has been illustrated above with reference to some preferred embodiments, it must be understood that many modifications and combinations of different features of the embodiments can be made. All such modifications fall within the scope of the appended claims.

Claims

1. A surveying device, specifically a total station, wherein, The surveying equipment includes: A base and an aiming component, the aiming component being rotatable relative to the base about two alignment axes. An angle determining device configured to generate angle data that provides orientation of the aiming component relative to the two alignment axes, and A laser distance measurement module is configured to generate a distance measurement beam for single-point measurement to determine the distance to a measurement point aimed at by the distance measurement beam, wherein the distance measurement beam is emitted from the aiming component via a beam exit. Its features are, The surveying equipment includes a ranging imaging module, which comprises a target illuminator arranged at the aiming component and a fixed imaging optical path arranged at the aiming component to image the radiation emitted by the target illuminator returning from the environment to the ranging imaging sensor. The target illuminator is configured to provide area illumination under different illumination states, including a wide illumination state and a narrow illumination state, wherein the wide illumination state provides illumination of a larger volume compared to the narrow illumination state, and The ranging imaging sensor is configured to provide depth image generation using area illumination returned from the environment by the target illuminator, wherein the depth image is generated with reference to angle data from the angle determination device. The surveying equipment is configured to provide the allocation of sub-regions within the area to be measured based on the distance distribution of measurement points in the area to be measured, wherein each of the sub-regions is associated with the orientation of the aiming component about one or both of the two alignment axes and with one of the different lighting conditions. The surveying device is configured to automatically execute a scanning sequence for measuring the area to be measured by: sequentially setting each of the orientations of the aiming component associated with the sub-region, and generating a depth image for each of the orientations of the aiming component using the associated illumination state provided by the allocation of the sub-regions within the area to be measured. The surveying equipment is configured to use a reference to the angle data from the angle determining device to provide a transformation of coordinate information from the depth image to a common coordinate system.

2. The surveying equipment according to claim 1, wherein, The different lighting states include a medium lighting state, which provides a larger volume of illumination compared to the narrow lighting state and a smaller volume of illumination compared to the wide lighting state.

3. The surveying equipment according to claim 1 or 2, wherein, The surveying equipment is configured to provide a display of the surrounding environment and to respond to user input queries to select the area to be measured.

4. The surveying equipment according to claim 1 or 2, wherein, The surveying equipment is configured to use the wide illumination state to generate an initial depth image or a sequence of initial depth images at different orientations of the aiming component about one or both of the two alignment axes, and to use the initial depth image or the sequence of initial depth images to determine the distance distribution for providing the allocation of the sub-regions within the area to be measured.

5. The surveying equipment according to claim 1 or 2, wherein, The surveying equipment is configured to access a digital 3D model of the environment and use the digital 3D model to determine the distance distribution for providing the allocation of the sub-regions within the area to be measured.

6. The surveying equipment according to claim 1 or 2, wherein, The surveying equipment is configured to provide display and editing functions, which include: Displays a representation of the area to be measured. The allocation of the sub-regions within the area to be measured, and The query user input provides an adjusted allocation of sub-regions within the area to be measured. The scan sequence is performed based on the adjusted allocation.

7. The surveying equipment according to claim 1 or 2, wherein, The surveying equipment is configured to provide the allocation of the sub-regions within the area to be measured by the following operations: The measurement area is provided with one or more wide-angle regions, each corresponding to an illumination area illuminated by the wide illumination state for the associated orientation of the aiming component, wherein a single wide-angle region or a combination of the wide-angle regions provides complete coverage of the measurement area. The scanning pattern generated by the following operations is executed: the aiming component is moved about one or both of the two alignment axes, and the distance is determined using the distance measuring beam of the laser distance measuring module in different orientations of the aiming component, wherein distance determination by the distance measuring beam is provided in each of the one or more wide-angle regions, and The segmentation of the one or more wide-angle regions is provided by using a distance determined by the scanning mode, wherein at least one wide-angle region is segmented into smaller-angle regions, and each of the smaller-angle regions corresponds to an illuminated area provided by the associated orientation of the aiming component and by an illumination state that provides illumination of a smaller volume compared to the wide illumination state in the different illumination states.

8. The surveying equipment according to claim 1 or 2, wherein, The ranging imaging sensor is configured to provide settings for activity detection zones of different sizes, and the surveying device is configured to coordinate the settings for the different sizes of activity detection zones with the settings for the different illumination states of the target illuminator.

9. The surveying equipment according to claim 8, wherein, By taking into account the distance determined by the laser distance measurement module or the ranging imaging module, the ranging imaging sensor is configured to provide settings for activity detection zones of different sizes, and the surveying device is configured to coordinate the settings of the activity detection zones of different sizes with the settings of the different illumination states of the target illuminator.

10. The surveying equipment according to claim 1 or 2, wherein, The surveying equipment is configured to operate within three defined distance measurement ranges: a short-distance measurement range, a medium-distance measurement range, and a long-distance measurement range. The short-distance measurement range covers distances shorter than the medium-distance and long-distance measurement ranges; the medium-distance measurement range covers distances longer than the short-distance range and shorter than the long-distance measurement range; and the long-distance measurement range covers distances longer than the short-distance and medium-distance measurement ranges. The allocation of the sub-regions includes: The sub-region associated with the narrow lighting condition is assigned to the medium-distance measurement range. Assign the sub-regions associated with the wide illumination state to the short-distance measurement range, and The additional sub-regions are assigned to the long-distance measurement range. The scanning sequence includes switching between the laser distance measurement module and the ranging imaging module, so as to... In the additional sub-regions allocated to the long-distance measurement range, distance determination is performed using the laser distance measurement module and the distance measurement beam. In the sub-region assigned to the medium-distance measurement range, the ranging imaging module is used to acquire a depth image using the narrow illumination conditions for distance determination; and In the sub-region assigned to the short-distance measurement range, the ranging imaging module is used to acquire a depth image using the wide illumination state for distance determination.

11. The surveying equipment according to claim 1 or 2, wherein, The laser distance measurement module is configured to generate the distance measurement beam having a center wavelength in the range of 620 nm to 700 nm, and the target illuminator is configured to generate the area illumination having radiation in the wavelength range of 930 nm to 950 nm, and the fixed imaging optical path includes an optical bandpass filter for blocking radiation outside the wavelength range of the area illumination.

12. The surveying equipment according to claim 1 or 2, wherein, The different lighting states have different transmit powers and / or different modulation frequencies for the area lighting, and / or The ranging imaging module is configured to set the modulation frequency on the ranging imaging sensor and the trigger frequency for triggering the emission of the area illumination based on the different illumination states and the pivoting speed of the aiming component about one or both of the two alignment axes.

13. The surveying equipment according to claim 1 or 2, wherein, The aiming component includes a receiving aperture for the fixed imaging optical path and different transmitting apertures for providing the different illumination states, wherein the different transmitting apertures are arranged in a point-symmetric manner around the receiving aperture.

14. The surveying equipment according to claim 13, wherein, The target illuminator includes three separate transmitting holes arranged in a circular pattern with point symmetry around the receiving hole.

15. The surveying equipment according to claim 13, wherein, The target illuminator includes six separate transmitting holes, which are arranged in a circular pattern in a point-symmetric manner around the receiving hole.

16. The surveying equipment according to claim 1 or 2, wherein, The target illuminator includes a radiation source and is configured to adapt to the diffusion behavior of the radiation source to provide switching between the different lighting states.

17. The surveying equipment according to claim 1 or 2, wherein, The surveying equipment is configured as follows: The reference point is automatically identified within a first depth image generated by the ranging imaging module on the first orientation of the aiming component using the coordinates of a reference point in the environment determined by the laser distance measurement module. The aiming component is automatically pivoted about one or both of the two alignment axes to move the position of a reference point within the field of view of the ranging imaging sensor, and to identify the reference point within a second depth image generated on a second orientation of the aiming component that is different from the first orientation of the aiming component. The field-of-view correlation correction parameters for determining the coordinates from the depth image of the ranging imaging module are determined using the coordinates of the reference point determined by the laser distance measurement module and the coordinates of the reference point determined from the first depth image and the second depth image.

18. The surveying equipment according to claim 1 or 2, wherein, The surveying device includes at least one imaging sensor for capturing 2D images of the environment, wherein the surveying device is configured to provide a transformation from coordinate information of the 2D image to the common coordinate system, wherein the surveying device is configured to: Analyze the 2D image to determine the coordinate parameters of comparison points in the environment imaged by the 2D image. Identify the comparison point within the depth image generated by the ranging imaging module, and The coordinate parameters and the coordinates of the comparison point determined from the corresponding depth image are used to determine the field-of-view correlation correction parameters for determining the coordinates from the depth image of the ranging imaging module.

19. The surveying equipment according to claim 18, wherein, The surveying equipment is configured to capture the 2D image to provide colorization of the point cloud generated using the laser distance measurement module. The at least one imaging sensor is arranged at the aiming component and generates the corresponding depth image in the same orientation of the aiming component as that used to capture the 2D image.

Images