METHOD FOR DETERMINING THE SUITABILITY OF A POSITION AS A SURVEYING STATION

Description

[0001] The present invention relates to a method for on-site determination of the suitability of a position of a terrestrial coordinate measuring machine, in particular a laser scanner or a total station, as a stationing according to claim 1.

[0002] A variety of measurement methods have been known since ancient times for recording the properties of defined points in a measurement environment, particularly data with a spatial reference. The position and orientation of a surveying instrument, as well as the direction, distance, and angle to measuring points, are recorded as standard spatial data. A well-known example of such coordinate surveying or geodetic instruments is the theodolite or total station, which are designed for highly accurate single-point measurements. A prior art geodetic surveying instrument is described, for example, in EP 1 686 350. Another type of generic terrestrial coordinate measuring instrument is scanning devices such as laser scanners, which are designed to record a very large number of object points in order to, for example, create a three-dimensional image of building or workpiece surfaces in the form of point clouds.Modern devices can have a camera that is aligned and / or pivotable in the target direction for capturing an image, wherein the captured image can be displayed in particular as a live image on the display of the display control unit and / or on a display of a connected peripheral device such as a tablet.

[0003] Such terrestrial, stationable devices have angle and distance measurement functions that allow the determination of direction and distance to a selected target. The angle and distance values ​​are determined in the device's internal reference system and must be linked to an external reference system for absolute positioning. Typically, the position of the surveying device in the external reference system serves as the basis for this.

[0004] In principle, such station coordinates and the orientation of the measuring device at the location can be calculated as a so-called free stationing from measurements taken at already absolutely referenced points in the measuring environment. A variety of methods are known in the state of the art that enable referencing of the respective device position as a stationing. Methods are also known that allow multiple measuring areas of a measuring environment from different stationings to be subsequently related to each other or to the same reference system, e.g., in post-processing as so-called registration of 3D point clouds.

[0005] A measuring environment cannot often be completely surveyed from a single stationing, e.g. because one or more sides of an object are facing away from the device, the measuring environment is winding (e.g. several rooms in a building) or objects are partially shaded by other objects. For this reason, a single stationing is usually not sufficient; instead, the device must survey the measuring environment from several positions. In doing so, all relevant areas of the measuring environment or all required object points should be surveyed, i.e. a seamless survey should be carried out. It is often difficult or time-consuming for a user to decide which position is suitable for a stationing or - particularly when a large number of stationings are required - to find an optimal measuring path (as a successive sequence of survey locations) which avoids unnecessary stationings oravoid duplicate measurements without "forgetting" surrounding areas.

[0006] EP 1 903 303 B1 proposes a method for filling survey gaps, comprising acquiring main point cloud data in a predetermined measurement area using a laser scanner, detecting an area without acquired data, acquiring supplementary image data of the area without acquired data from at least two directions using an additional image acquisition device, preparing a stereoscopic image based on the supplementary image data obtained from the additional image acquisition device, acquiring supplementary point cloud data in the area without acquired data using an image measurement based on the stereoscopic image, and supplementing the area of ​​the main point cloud data without acquired data by comparing the main point cloud data with the supplementary point cloud data. The method is intended for post-processing. On-site information or advance information on non-acquired areas is therefore not available.

[0007] EP 3 062 066 A1 discloses a method with which suitable measurement positions for a surveying unmanned aerial vehicle (UAV) can be provided on site or in advance. For this purpose, reference points of an object are determined using a terrestrial surveying device such as a total station or a laser scanner, on the basis of which reference points the measurement positions to be assumed by the UAV for the actual surveying of the object can be derived. With this very specific and complex method, a suitable surveying flight path for a surveying UAV can be determined in advance. For improved surveying from multiple locations or for improved stationing using a terrestrial device such as a laser scanner or a total station itself, however, this teaching offers no assistance.

[0008] JP 2018 138883 A teaches a method in which, based on a virtual model of an object to be surveyed, created from images of the object, the survey locations to be taken for a subsequent survey are calculated. Disadvantages of this method include, among other things, that only simulated locations are provided and that the survey requires considerable effort, including the user photographing the entire object.

[0009] US 2017 / 0123066 A1 discloses a laser-based system for point cloud creation using an IMU, whereby images of the scanned environment can be shown to the user on a display based on the point cloud.

[0010] The object of the invention is therefore to provide a method for automatically supporting the stationing of a mobile or portable terrestrial opto-electronic coordinate measuring machine.

[0011] In particular, it is a further object of the invention to provide such a method in which successively suitable or optimal successive locations for surveying are automatically determined and, if necessary, provided.

[0012] At least one of these objects is achieved by implementing the characterizing features of the independent claims. Features that further develop the invention in an alternative or advantageous manner can be found in the dependent claims and the description, including the descriptions of the figures.

[0013] The invention relates to a method for determining a suitable or optimal stationing of a terrestrial optoelectronic coordinate measuring machine within a measuring environment. The coordinate measuring machine is designed for the measurement beam-based determination of object coordinates, e.g., as a laser scanner or total station. Within the scope of the method, a first measuring area is surveyed from a first stationing location. The coordinate measuring machine is then moved from the first stationing location for a stationing change, and the measuring environment is optically recorded during the stationing change.Based on the measurement environment recorded in this way, at least one task area is determined as an area of ​​the measurement environment which is to be measured, and based on the measurement environment recorded in this way, at least one field of view is determined as an area of ​​the measurement environment which is or could be measured from a current position of the coordinate measuring machine taken during movement.

[0014] The data thus provided regarding the measuring range, task range and visibility range serve as the basis for a combined analysis of the first measuring range, the task range and the visibility range, by means of which the position is checked for suitability as a station.

[0015] Preferably, this type of check is performed with regard to suitability as a second and subsequent stationing, i.e., following or directly following the first stationing. Automatic "live" position checking thus ensures that consecutive measurement areas of the measurement environment are surveyed successively without creating any gaps in the survey.

[0016] Preferably, the optical recording of the measurement environment occurs continuously during movement, in particular with the task area being continuously updated based on the continuously recorded measurement environment data and / or the check for suitability for stationing also being continuously performed. By continuously checking the respective position, the position change during movement can advantageously be continuously monitored, so that, for example, an unsuitable position can be immediately identified or immediately detected when a suitable positioning area is left.

[0017] Preferably, the optical recording of the measurement environment during movement is carried out using a measuring beam-based profiling and / or coarse scanning (scanning with a low resolution / point density). For example, the device designed as a laser scanner is operated in profiler mode during the position change, meaning that only the axis parallel to the vertical direction is moved, so that the measuring beam records a profile of the environment (e.g., a floor plan). Alternatively or additionally, the optical recording is carried out photographically using panoramic image capture, stereo photogrammetry, depth imaging, a range image camera, and / or an overview camera of the coordinate measuring machine.

[0018] Optionally, the device comprises a holding device for easier movement, in particular a handle, which is designed to enable a user to carry the device in a manner advantageous for capturing the measurement environment, in particular wherein the holding device is designed to support the device tilted by 90°. Optionally, the device comprises a display unit for displaying a tilt angle, wherein the (analog or digital) display unit is positioned in particular such that it can be read by a user carrying the laser scanner when the device is carried in a position tilted by 90°.

[0019] Optionally, the comparative analysis includes checking for overlaps and / or gaps between the measurement area, task area, and / or field of view, e.g., checking for overlaps between the measurement area and field of view. As a further option, the analysis includes checking for gaps between the task area and field of view.

[0020] This option optionally determines the presence of gaps or overlaps based on point correspondences between the areas. In particular, a gap is determined based on points in the task area that have no correspondences in either the measurement area or the visual area. In other words, the presence or absence of corresponding points between the areas is checked.

[0021] Optionally, point correspondences are determined based on point distances, with normal vectors of points also being considered as a further option, and / or point correspondences are determined based on matching and / or tracking local image features, in particular, where local image features are described by descriptors. Alternatively, local image features can also be described by encodings based on deep learning.

[0022] Optionally, the procedure can issue a user warning as soon as the position is determined to be unsuitable for stationing or the test result is negative. For example, an acoustic or illuminated warning is issued if the current field of view no longer allows for continuous surveying or if unsurveyed portions of the task area remain along a previously traveled path.

[0023] In a further development of the method, based on the result of the test, a suitable and / or unsuitable location and / or a suitable and / or unsuitable location zone and / or existing or potential coverage gaps in the task area are determined and provided as user output. Based on the checked position(s), the user is given information about which position(s) are suitable for a survey, particularly those following the previous survey, or conversely, which are not suitable. Gradual classifications are also possible, meaning the degree of suitability can be determined and output, for example, as a percentage, so that, for example, conditional suitability is represented. This information is optionally displayed graphically using a map of the measurement environment, e.g.by marking (un)suitable surrounding zones or (potential) measurement gaps or (potential) stations with (potentially) insufficient measurement overlap in color or with a pattern.

[0024] In the case of an automotive coordinate measuring machine, a determined suitable location can also be automatically adopted. As an additional option, a suitable alignment or orientation of the measuring device can be determined and output, and / or automatically adopted if the appropriate motorization is available.

[0025] In a further development of the method, a suitable position is determined as the optimal second, preferably next, stationing based on at least one predefined optimization criterion. An optimization criterion could be, for example, a seamless connection of a second or further measurement range to the (first) measurement range with a defined, in particular defined minimal, overlap with the first measurement range. The overlap is defined, for example, such that it is (just) sufficient for registering the point clouds of the first and second measurement ranges without generating an unnecessary / redundant "excess" of measurement data.

[0026] Alternatively or additionally, an optimization of the sequence of the surveying process can be considered as an optimization criterion, e.g. surveying the entire task area (the entire measuring environment) with as few stations as possible, as little time as possible, high geometric accuracy of the stations to each other and / or as short a distance as possible between the stations.

[0027] As a further alternative or further possibility, the optimization criterion relates to the angle of incidence of the measuring beam on the object surface and / or a resolution, particularly local, of the coordinate measurement. For example, a position is optimized to determine the optimal position from which particularly relevant objects or zones (regions of interest) can be measured with high resolution and / or low noise or with a good measurement signal level. For example, positions that allow targeting of an object but would result in too low a point density or insufficient measurement precision on one or more objects or zones during surveying are automatically classified as unsuitable or less suitable for stationing.

[0028] For example, as part of the optical recording of the measurement environment, object detection is optionally carried out, in particular with the comparative analysis of the measurement area, task area, and field of view being carried out based on such detected objects or their object points. Another option is to classify objects, e.g., based on their relevance to the measurement, for example, by classifying them as highly relevant, relevant, or irrelevant.

[0029] Optionally, filtering is performed when determining the scope of work for objects and / or surrounding areas that are not to be measured. Uninteresting objects or areas are thus eliminated and not included in the scope of work.

[0030] Another option is optical acquisition of the measurement environment using simultaneous localization and mapping, LIDAR simultaneous localization and mapping, structure from motion, and / or dense matching algorithms. Another option is acquisition using additional data acquired from at least one position, direction, and / or acceleration sensor of the coordinate measuring machine.

[0031] The invention further relates to a computer program product according to claim 14.

[0032] Furthermore, the invention relates to a terrestrial opto-electronic coordinate measuring machine according to claim 15.

[0033] The method according to the invention thus advantageously enables the automatic on-site testing of surveying device positions for suitability as a station. This relieves the user of the task of independently examining locations for suitability. This allows the user to move around the measuring environment with the device, while the device continuously checks for suitable positions and warns of unsuitable positions. Above all, the user can gradually walk through the measuring environment, starting from an initial station, with the method automatically determining the next suitable station, so that the entire measuring environment is gradually surveyed from successive stations.For example, the user picks up the surveying device after surveying from the first station, walks until he receives a stop signal thanks to the procedure, sets the device down at the position he has then reached or at the last position determined to be suitable, measures from this second station, picks up the device again and is guided to the next (third) station, etc.

[0034] What is particularly advantageous is that the method can be used to automatically find not only a suitable position but also an optimal position based on optimization criteria. Finding such a position has previously usually required a trained, experienced user. With the method according to the invention, on the other hand, criteria such as resolution and angle of incidence of the measuring beam on a surface are automatically taken into account, so that measuring can be carried out with optimal parameters in this respect and unfavorable low resolutions or angles of incidence, which lead to excessive smearing of the measuring point, are avoided. This can optionally be advantageously combined with object recognition and object classification, so that optimization criteria can be applied specifically with regard to (particularly) relevant objects. Optimization can also be advantageous with regard to the measuring process as a whole, so that the entire measuring environment is measured optimally, e.g.B. with as few and therefore optimal stationing as possible.

[0035] The method according to the invention and the measuring device according to the invention are described in more detail below by way of example only with reference to concrete embodiments shown schematically in the drawings, wherein further advantages of the invention are also discussed.

[0036] Illustrate in detail Fig. 1 shows an exemplary embodiment of a generic terrestrial opto-electronic coordinate measuring machine, designed as a laser scanner; Fig. 2 shows a laser scanner measuring an interior space from a first measuring position; Fig. 3a-e shows a first example of a method sequence according to the invention; Fig. 4a-b shows a further example of an automatic position suitability determination method according to the invention; Fig. 5a-b shows an example of detecting the measuring environment for stationing testing; and Fig. 6a-d shows further developments of the coordinate measuring machine 1 according to the invention and the method.

[0037] The Figure 1shows an exemplary embodiment of a generic terrestrial optoelectronic coordinate measuring machine, in this example designed as a laser scanner 1. This has an upper part 10, which is connected to a base 17 in a motorized manner about a vertical axis 9, which in this example is arranged on a tripod 19. Located in the upper part 10 are the light transmitter 11 for emitting a measuring beam 5 of the laser scanner 1, a light receiver 15 for receiving reflected portions of the measuring beam 5, and a beam splitter 13. A beam steering unit 16, which has a mirror, is attached to the upper part 10 in a motorized manner about a transverse axis 8. The transverse axis 8 is orthogonal to the vertical axis 9. By rotating 6 the beam steering unit 16 about the transverse axis 8, the measuring beam 5 is guided vertically over a surface, while by rotating 7 the entire upper part 10 about the vertical axis 9, the measuring beam 5 is guided horizontally over the surface.

[0038] A control and evaluation unit (not shown here) is in data communication with the light transmitter 11 and the light receiver 15 in the upper part 10. The control and evaluation unit or parts thereof can also be arranged outside the upper part 10, for example as a computer connected to the base 17. The control and evaluation unit is designed to determine the distance of the laser scanner 1 to the measurement object for a plurality of measurement points from the travel time of the measurement beam 5 and its reflected portions. For this purpose, for example, the phase shift between the emitted measurement beam 5 and the received radiation can also be determined and evaluated. A display device (not shown here) can be connected to the control and evaluation unit, which can be designed as a display directly on the laser scanner 1 or as a display of a connected computer.

[0039] The embodiment of the surveying device 1 shown here for determining object point coordinates is purely exemplary, and possible modifications are known from the prior art. Another example of such a device is a total station or electronic tachymeter, with which single-point measurements can be performed, e.g., in the context of geodetic surveys.

[0040] Figure 2 shows the first embodiment of the laser scanner 1 when measuring a measuring environment designed as an interior space 3 from a first measuring position or stationing 41.

[0041] By means of the (rapid) rotation 6 of the beam steering unit, the surfaces of the measurement environment 3 are scanned by the measuring beam 5 along a vertical circular line. By means of the (slow) rotation 7 of the upper part relative to the base, the entire space is gradually scanned with these circular lines. The totality of the measurement points 51 of such a measurement is referred to as a scan and can, for example, result in a point cloud.

[0042] In addition to the determined distance to the laser scanner 1 (or to the origin of the reference system), each measuring point 51 can also have a brightness value, which is also determined by the control and evaluation unit. The brightness is a grayscale value, which is determined, for example, by integrating the bandpass-filtered and amplified signal from the light receiver 15 over a measurement period assigned to the measuring point 51.

[0043] Optionally, images can also be generated using a color camera of the coordinate measuring machine 1, which can be used to assign additional color values ​​to the measurement points 51. Such a camera can be designed, for example, as an overview camera. Furthermore, such surveying devices 1 with one or more cameras are also known, with which panoramic images of the measurement environment 3 can be captured.

[0044] By optically scanning and measuring the environment of the laser scanner 1, a scan of a specific object is created or, more generally, object points 51 are measured in a coordinated manner. There are often objects to be recorded or measurement environments 3 that cannot be captured with a single scan or from a single location 41, for example, winding interior spaces or multiple rooms in a building. To measure these, a user is supported by the method according to the invention, as described with reference to the following figures, by automatically checking positions for suitability for stationing.

[0045] In the Figures 3a-3e An arrangement of several rooms 3a-3d is shown in the form of a floor plan as an exemplary object 3. This measurement environment 3 is to be measured in its entirety.

[0046] For this purpose, the laser scanner must be set up at different stations, with the first station 41 in the Figure 3a The device-fixed origin of the laser scanner's reference system thus reaches several different spatially fixed centers of the laser scanner. The various scans are then arranged in a common coordinate system, e.g., as a so-called registration. For such registration, a certain overlap of the measurement areas or point clouds is advantageous or necessary.

[0047] In Figure 3aThe laser scanner is set up at a first measurement position 41 in one of the rooms. Through the rapid vertical rotation of the beam steering unit and the slow horizontal rotation 7 of the upper part relative to the base, the surfaces 50, i.e., walls, floor, and ceiling (indicated in the figure by the thick black lines) of the first part of the measurement environment 3 are gradually scanned as the first measurement area M (gray rasterized area), resulting in a first point cloud.

[0048] In Figure 3bThe laser scanner is moved along path 4 from the first measurement position 41 to a first position P1 for the stationing change. For example, within the scope of a stationing determination functionality of the laser scanner, the measurement environment 3 is optically recorded from the first position P1, in the example by taking 40 a panoramic image or a 360° panoramic photograph, for which, for example, a camera of the laser scanner is pivoted by rotating the upper part of the scanner, symbolized by arrow 7a. Alternatively, such recording can be performed optically, for example, by a (rough) lidar scan.

[0049] For simplicity, in the example, the measurement environment 3 is first recorded at position P1. However, the method preferably involves continuously recording the measurement environment during the stationing change along path 4, starting from the measurement position 41, e.g., by continuously taking photographs at a specific recording rate or continuously profiling with the laser beam of the laser scanner. The evaluation and analysis of the measurement environment data recorded in this way, as described below, is also preferably carried out continuously, so that a large number of positions are checked for stationing suitability, or the current position is continuously monitored for suitability.

[0050] In Figure 3cIt shows how the recorded measurement environment data is evaluated to check position P for suitability as a station. Based on the recorded measurement environment data, a task area O (dotted partial area) is determined. This is understood to be an environmental area that is to be surveyed, for example, scanned. In the example, this is the already scanned measurement area M (checkered partial area) and the access area 3b to the two smaller rooms 3c, 3d. The measurement area M can therefore be viewed as a sub-area or subset of the task area O.

[0051] Furthermore, a field of view V is determined based on the recorded measurement environment data. This refers to the part of the measurement environment that is visible or measurable from position P1. In the example, both the large room 3a and the access area 3b are visible from position P1; in other words, the visible area V coincides with the task area O. Mathematically speaking, the field of view V and the task area O are identical.

[0052] Since, from position P1, the field of view V completely encompasses the (previously determined) task area O (or the task area O is at least a subset of field of view V), the test shows that the current position P1 of the coordinate measuring machine is suitable for stationing. This means that the laser scanner can or could be set up at the current location to measure additional parts of the measuring environment M, or in other words, to scan another measurement area.

[0053] In the example, however, the user or device continues its movement without measurement ( Figure 3d ) and reaches position P2. From this position P2, further recording of measurement environment 3 takes place. From the recorded environmental data, a further task area O results, or rather, as shown, the task area O is updated (here: expanded); it now includes the access area to the rooms as well as part of one of the two small rooms.

[0054] Next, the field of view V is determined again. In the example, the task area O is not completely contained within the field of view V; a part V1 of the task area O is not visible or detectable from position P2. However, this part V1, which is "invisible" from the current position P2, is part of the measuring area M and has therefore already been measured.

[0055] The comparative analysis examining position P2 shows that the task area O is not completely contained in the field of view V, meaning that part of the task area O is not visible from location P2. However, this is not considered problematic, since this area of ​​the measurement environment has already been scanned, and the invisible area V1 is therefore a subset of M. In addition, there is a (sufficiently large) overlap area between the field of view V and the measurement area M (in the example according to Figure 3d The overlap area corresponds to the entire measuring area reduced by the "invisible" part V1 ). Through this intersection, a second measuring area recorded from location P2 can be linked (with sufficient accuracy / robustness) to the first measuring area, e.g., a second 3D point cloud of the second measuring area can be registered in the coordinate system of a first 3D point cloud of the first measuring area M.

[0056] Thus, position P2 is also suitable for stationing. A second measuring range surveyed from there will or would ensure a seamless connection with the first measuring range M, with sufficient overlap.

[0057] In Figure 3e It shows how the coordinate measuring machine continued its path 4 and has now reached the third position P3 in a small room 3c. Based on the optical—in this example, photographic—image of the measurement environment, the task area O is updated. In the example, it is determined that the surfaces of room 3c are added to the measurement task and must be scanned.

[0058] In the example, the overlap zone to the measuring range M is significantly smaller than in the example according to Figure 3d(in the drawing, the freely visible checkered triangle at the lower left edge of the measuring range M), but the field of view V still ensures sufficient connection to the measuring range M. Thus, a suitability condition is also met in position P3. Further, as before (cf. Figure 3d ) the no longer visible area V1 is unproblematic as it has already been measured (subset of the first measuring area M).

[0059] However, the analysis of the recorded measurement environment data shows that from the third position P3, the task area O is no longer fully measurable or has not yet been measured. There is a sub-area V2 of the task area O that is not visible and is not a subset of the already measured measurement area M. Thus, starting from position P3, there is an area of ​​the measurement environment that has not yet been measured, but is recognized as being to be measured, yet cannot be measured from position P3.

[0060] It is therefore automatically determined that there is an area V2 of the measuring environment 3 which is part of the task area O, but is neither part of the already scanned measuring area M nor part of the field of view V.

[0061] Thus, a necessary condition for suitability for stationing in the third position, P3, is not met. The overall test result is negative, and position P3 is unsuitable (at least as the next stationing location; as described below, the inventive testing method can be further refined to allow for gradations between the two poles of suitability and unsuitability).

[0062] The analysis result of an unsuitable position P3 (as the next stationing) is displayed, for example, to the user moving the measuring device, e.g., by an acoustic or visual warning, so that they can react accordingly. Based on an analysis of areas to be surveyed, areas that have already been surveyed, and areas that could be surveyed from the current position, any missing or uncovered areas are automatically determined by the method according to the invention and visualized, e.g., using a graphic overview / visual map of the measuring environment on a tablet or the like, so that the user can be informed accordingly, e.g., while changing location to assume the next or further stationing.

[0063] During a continuous check of the current position along route 4, for example, the user is provided with information about the suitability for stationing via a light indicator, e.g., an LED that glows green as long as the position is suitable for stationing and turns red as soon as the check shows that the current position is unsuitable for surveying or as the next stationing. Alternatively, or in addition, a warning tone is emitted when an unsuitable location is reached.

[0064] Alternatively or additionally, such a suitability check and corresponding optional user information are also performed in stages. For example, such an LED lights up orange if the current position is only partially suitable for stationing (not mandatory or unsuitable in any case).

[0065] Referring to the example according to Figure 3eIt can be automatically recognized that scanning from position P3 initially leads to gap V2, but that this gap V2 can be closed by continuing along path 4 and stationing at another position along the path continuation to / into area 3b (i.e., gap V2 can be closed in the future, so to speak). In such a training course, the two classification categories of suitable and unsuitable are further differentiated into those positions that are suitable for stationing if (at least) one further stationing is added as the survey continues.

[0066] In contrast, a "backward" gap, i.e., a gap that remains open when continuing along path 4, would result in a "red" warning being issued by the measuring system. For example, if the user were to leave room 3c and proceed into room 3b without having measured (room 3c) from position P3, such a warning would be issued, since room 3c would then remain unmeasured as part of the task area O. It is therefore checked whether a position leaves behind any surrounding areas to be measured, or at which position a measurement gap remains that will no longer be filled in the future, and / or at which position there is no sufficient overlap with an already existing measurement area M and cannot be created in the future.

[0067] In the above-mentioned embodiments with map-based visualization of the measurement environment or the task, visibility, and / or measurement area (e.g., in a bird's-eye view), such warnings or user information can also be presented graphically. For example, positions (or position zones) that are always suitable for stationing are marked in green, positions that are suitable in certain cases or only to a limited extent are marked in orange, and positions that are definitely unsuitable are marked in red. Additionally or instead, potentially problematic surrounding areas (possible measurement gaps) can also be displayed graphically and, for example, in color. Based on such an overview, the user is automatically shown (particularly) suitable and / or potentially problematic locations. Such a visualization can thus represent a planning basis or a type of navigation aid, which the user can use to optimally plan the survey of the task area O, e.g.,with regard to seamless metrological coverage of the task area O with as few and / or optimally overlapping measurement areas / stations as possible, or an optimal route 4. Such optimization criteria can therefore be taken into account in a further development of the method (independent of such visualization) in order to further refine the position check. Examples of optimization criteria that can be specified are the complete survey of the measurement environment 3 with minimal time expenditure, a minimum number of stations, optimal scan resolution (e.g., maximum or sufficiently high), or high geometric accuracy / conformity of the stations to one another. If several such optimization criteria are considered, these may partially contradict each other.In such cases, a trade-off can be made automatically so that, in a kind of compromise, optimal positions are automatically determined that best meet the selected criteria, whereby, for example, the user can also specify a weighting of the individual criteria.

[0068] Such a procedure is carried out in particular step by step or dynamically adapting, so that the user does not necessarily or rigidly have to follow a plan once it has been drawn up, and accordingly in a visualization this is continuously updated, for example to the respective location or path 4 or each time after recording a further measuring area.

[0069] In the Figure 4a and 4b Further examples of a position suitability determination method according to the invention are shown.

[0070] After the procedure according to Figure 4aIn a step 20, a first object scan is carried out in a first stationing by means of a terrestrial coordinate measuring machine with one or more scanning means for scanning surfaces, whereby a first measuring range M is generated as first data.

[0071] In step 21, the device is moved within the measurement environment, and scanning equipment automatically detects areas of the measurement environment, such as walls, ceilings, floors, etc., that are to be measured. For example, the detection is performed by rotating the laser beam of a scanning device around two axes (one faster and one slower axis of rotation) and scanning surfaces at low resolution (significantly lower than the resolution used for measurement). This generates a task area O, which continuously grows as the measurement beam sweeps over new environmental / object areas.

[0072] During the movement, in step 22, areas V are automatically recorded using scanning devices that may be the same as those used to capture the task area, i.e., the surrounding area visible or measurable from the current position. For example, area V is a subset or subset of the task area O, resulting from the last 180° rotation of the slow axis of rotation.

[0073] Based on the data from the measuring range M, the task range O, and the field of view V, an automatic convergent analysis is carried out in step 23, whereby points between the ranges M, O, and V are examined for correspondence. When assigning a correspondence between two points, e.g., a point from the field of view V and one from the task range O, the distance between the points and the scan resolution are taken into account. A lack of point correspondence is determined, for example, if, with a scan resolution of 20 cm, there is no nearest point within 20 cm in another range V, O, or M to a point in one range M, V, or O.

[0074] Optionally, normal vectors to the respective points can be calculated and taken into account during the analysis with regard to point correspondences. This can be done, for example, by determining a neighborhood set that represents neighboring object points of a respective area or coarse scan. Neighboring object points are, for example, two object points with the smallest distance to each other, or all object points that have a distance of less than a certain limit to an object point, or a certain number of object points that have the smallest distance to a selected object point, for example, the three object points with the three smallest distances. Based on the neighborhood set, object surfaces and their associated surface normals are estimated, i.e., a type of real-time geometry recognition is carried out, e.g.by placing a mathematical plane through all points of a neighborhood set or by other approximation methods. The area is determined, for example, by fitting a plane using several object points using mathematical methods known to those skilled in the art. Finally, the surface normal of the plane is calculated. If the surface is not estimated by determining a mathematically exact plane, but rather by some other modeling, the surface normal is, for example, an average value of several individual surface normals. A point correspondence is assumed when the distance between the points of two surrounding areas is small (or lies below a defined limit) and their normal vectors point at least essentially in the same direction. Thus, for example,an incorrect assignment of a point correspondence of points on the opposite side of a (thin) wall can be avoided, since these are only a short distance apart (approximately the wall thickness) but have opposing normal vectors.

[0075] Based on the result 24 of the point correspondence determination, it is automatically determined whether sufficient point correspondences exist (25a), i.e., whether there is a connection or overlap between the measuring range M, the task range O, and the visual range V at the respective instrument position, or whether there are points from the task range O that have neither a correspondence in the measuring range M nor in the visual range V, i.e., whether there is an uncovered area (25b). In the first case (25a), the instrument position is classified as suitable for stationing; in the second case (25b), it is classified as unsuitable.

[0076] Figure 4bshows a further method sequence. According to this method example, in a step 20', individual point measurements are performed (a set of individual object points is measured) in a first stationing using a terrestrial coordinate measuring device, e.g., a total station, whereby a first measurement range M' is generated as the first data.

[0077] In step 21', the device is moved within the measurement environment and, using cameras, automatically captures areas of the measurement environment to be measured, such as walls, ceilings, floors, etc. For example, capture is performed by continuously capturing panoramic images using a camera with a large field of view and / or a rotating camera, with the camera, for example, being integrated into the housing of the total station. This generates a task area 0'.

[0078] When creating the task area O', an object recognition algorithm based on computer vision and / or machine learning, e.g. deep learning, is used to automatically detect object points that are relevant for a surveying task or belong to objects to be surveyed, e.g. hydrants, manhole covers and the like.

[0079] The task area is then represented by a list of object points, e.g. as feature vectors, which continuously increases as new objects appear in the camera's field of view as the surveying device moves and are recognized as survey objects to be recorded.

[0080] In step 22', one or more cameras of the surveying device, which may be the same as those used to capture the task area, automatically capture areas V', e.g., using panoramic photography. These areas represent the currently visible area of ​​the measurement environment, i.e., the surrounding zone visible or measurable from the current position. Here, too, object recognition can be used in the same way as when creating the task area. The visible area V' is, for example, a subset of the task area O', which is detected in the current panoramic image corresponding to the current device position.

[0081] Based on the data from the measurement area M', the task area O', and the visual area V', a comparative analysis is automatically performed in step 23, examining points between the areas M', O', and V' for correspondence. Correspondence is assigned, for example, using feature matching or feature tracking.

[0082] Based on the result 24' of the determination of point correspondences, it is automatically determined whether sufficient point correspondences are present (25a), i.e. there is a connection or overlap of measuring range M', task range O' and field of view V' in the respective device position, or whether there are points from the task range O' which have neither a correspondence in the measuring range M' nor in the field of view V', i.e. an uncovered area and thus a position unsuitable as (next) stationing (25b).

[0083] In the Figure 5a and 5bAn example of capturing the measurement environment for stationing verification is presented. After surveying the measurement environment from the first stationing 41, a user 2 starts a stationing determination function on the laser scanner 1 and picks up the laser scanner 1 by the base or tripod, tilting the laser scanner 1 by approximately 90° as shown, so that the transverse axis 8 (the axis about which the beam steering unit is rotatable relative to the upper part) now runs essentially vertically or at least approximately follows the direction of gravity.

[0084] The user 2 then moves the laser scanner 1 in this position, while the laser scanner 1 automatically records the currently visible / accessible measurement environment as the field of view for the measurement beam and records the traveled path 4. This takes place in a profiler mode of the laser scanner 1. This is characterized in that the slow rotation of the upper part around the base is switched off, and thus measurement points are only measured in one plane. By tilting the laser scanner 1 by 90° by the user, a profile of the environment traveled on path 4 can be recorded using SLAM (simultaneous localization and mapping), or Lidar-SLAM, i.e. in particular, a floor plan can be recorded, from which the measurement environment locations (task areas) to be measured can be derived. With this arrangement, for example,A horizontal profile of the room (floor plan) is recorded as the task area, which is continuously expanded as the scanner moves through the room. For scanning tasks, such measurement environment points are, for example, walls, ceilings, floors, buildings, vegetation, etc. For single-point measurement tasks, e.g., in the context of geodetic surveys, task points are a set of surface points to be measured, such as the corners of a house, the center of a manhole cover, etc.

[0085] Preferably, means for stabilizing scanner 1 in profiler mode are provided to keep the scanning plane as horizontal as possible during movement. The horizontal orientation of scanner 1 can be optimized using both active and passive stabilization.

[0086] One possible means of passive stabilization could be a design of the upper section in which the center of gravity of the upper section is selected such that the transverse axis 8 automatically moves into the vertical position when the upper section is tilted by approximately 90°, as shown. To ensure this, the upper section must be able to rotate freely around the vertical axis.

[0087] For active stabilization, the transverse axis 8 can also be automatically rotatable in the direction of gravity as part of the position-checking functionality, in particular by a motorized rotation of the upper part relative to the base. To determine the direction of gravity, the laser scanner 1 can have one or more inertial measurement units (IMUs), of which at least one is preferably housed in the upper part. With the aid of an inertial measurement unit in the upper part, inclinations of the profiler plane relative to the horizontal can be compensated. For example, an inertial measurement unit is provided in the upper part, which is designed to determine an inclination of the transverse axis relative to the direction of gravity.The laser scanner is preferably designed to rotate the upper part relative to the base, depending on the determined inclination, around the vertical axis or relative to a holding device around a stabilized axis in a motorized manner so that the inclination of the transverse axis relative to the direction of gravity is minimized. An IMU or comparable sensors, e.g., a compass, can be used alternatively or in addition to support path recording or as an alternative to the use of SLAM.

[0088] Optionally, both the measurement rate and the rotational speed of the rotation axis can be reduced (compared to the actual measurement of the measurement environment) to save power. For example, surfaces are scanned with a reduced or coarse point density of 10 cm (relative to an object distance of several meters, e.g., 5 m).

[0089] Optionally, the scanner can also oscillate or rotate around its vertical axis during profiling. Instead of scanning a single plane of the room, a segment (or the entire room) is then scanned and can be used for mobile mapping. With a slight oscillation of the vertical axis (for example, by approximately ± 5°), a portion of the room's side walls is scanned. This allows for sufficient overlap when the device changes height.

[0090] As an alternative to such measuring beam-based means for capturing the measurement environment and deriving a task area and / or field of view, these means are, as already mentioned, designed as cameras, e.g., as a panoramic camera, depth camera, stereo camera, RIM camera, or the like. A panoramic or all-around camera, along with a scanner, is a preferred means for determining the field of view. These camera alternatives are particularly used with surveying devices such as total stations, which are designed for single-point surveying.

[0091] Preferably, or if both a camera and a profiler / scanning unit are available, both such camera devices and measuring beam devices are used to create the task area.

[0092] Optionally, object recognition algorithms are used for measuring environment detection or task area determination. Mitter's object recognition detects objects of particular interest, such as doors, windows, buildings, etc., with object recognition optionally based on machine learning. This can also classify objects that are detected but cannot be measured, e.g., because they are not a permanent part of the measuring environment (e.g., vehicles) or are of little interest. These objects are then not included as part of the task area. Such an object filter can prevent unnecessarily large task areas.

[0093] In conjunction with photographic recording of the measurement environment, algorithms such as Structure-From-Motion (SfM), SLAM, or Dense Matching, optionally based on deep learning algorithms, are used as an additional option. For example, a point cloud representing the objects to be measured is generated from the data of the images taken while moving along path 4.

[0094] Optionally, the laser scanner 1 can automatically switch to position check mode—either immediately after completing the scan of the first measurement environment, or when, for example, lifting or tipping by user 2 is detected. Likewise, the laser scanner 1 can optionally automatically exit position monitoring mode when it detects that it is placed at a potential or suitable measurement position.

[0095] In the Figures 6a-d Further developments of the coordinate measuring machine 1 according to the invention and the method are shown.

[0096] In Figure 6a It is shown how, during a continuous check of the current position along path 4, the user is provided with information about the suitability for stationing using an illuminated display 14, e.g., an LED that lights up green as long as the position is suitable for stationing and switches to red as soon as the check shows that the current position P is unsuitable for a survey or as the next stationing. Alternatively or additionally, a warning tone is emitted when an unsuitable location is reached.

[0097] For example, a continuous analysis of the constantly updated floor plan during movement along path 4 is used to detect whether the clear view to the last measuring area and / or task area is obstructed, for example when the laser scanner 1 is in the Figure 5 shown leaving a room.

[0098] In this case, for example, user 2 can be prompted to perform a new stationary scan from a position determined to be suitable. Likewise, the user can receive a warning if they exceed a certain distance from the last stationing or the last measurement area. As described in Figure 5 For this purpose, the laser scanner 1 can, via the output unit 14, output optical or acoustic signals to the user 2, for example, to prompt the user to perform a specific action, e.g., to return to the last suitable position, specifying the direction and distance, or to display this desired positioning on a representation of the determined floor plan. The output unit 14 can, for example, have a display field for outputting text messages or graphics (e.g., floor plan). The user can also be notified, for example, when the upper part 10 needs to be rotated.

[0099] Figure 6bshows a position change with another exemplary embodiment of the laser scanner 1. This is a hand-held laser scanner 1, which has a (e.g., handle-shaped) handle 12 for carrying by the user 2. This is advantageously attached to the upper part such that the laser scanner 1 can be carried tilted by 90°, and profiling can be carried out as part of the position test method. Such a handle 12 can preferably have a stabilized two-axis universal joint to automatically align the transverse axis 8 to the direction of gravity when the laser scanner 1 is held by the handle 12. Alternatively, the laser scanner 1 can also have a swivel joint in the handle 12 and active leveling via the vertical axis.

[0100] Figure 6cshows another exemplary embodiment of the laser scanner 1. This comprises means for tilting the upper part 10 by 90°. In this example, these are designed as a hinge 18 mounted in the base 17. By tilting the upper part 10, the user can eliminate the need to tilt the entire laser scanner 1, which can be particularly advantageous for large and heavy scanners.

[0101] The hinge 18 can either be operated by a user - in particular, tilting can then put the laser scanner 1 into profiler mode - or tilt the upper part 10 automatically, in particular motorized.

[0102] As in Figure 6d As shown, this embodiment of the laser scanner 1 can preferably be designed to be movable, ie in particular it can have wheels or rollers or it can be placed on a corresponding frame.

[0103] Optionally, the measuring device 1 also has a controlled motorization such that a previously determined suitable position and / or orientation of the device 1 can be automatically assumed by the device 1 itself.

[0104] It is understood that these figures only schematically depict possible embodiments. The various approaches can also be combined with each other and with prior art methods and devices.

Claims

1. Method for ascertaining a suitable deployment of a terrestrial optoelectronic coordinate measuring device (1) within measurement surroundings (3, 3a-3d), wherein the coordinate measuring device (1) is embodied for a measuring beam-based determination of object coordinates, wherein - a measurement region (M, M') is surveyed (20, 20') from a first deployment (41), - the coordinate measuring device (1) is moved away from the first deployment (41) for the purposes of changing the deployment, - measurement surroundings (3, 3a-3d) are automatically optically captured (40) within the scope of changing the deployment, - at least one task region (O, O'), as a region of the measurement surroundings (3, 3a-3d) to be surveyed (21, 21'), is ascertained automatically on the basis of the measurement surroundings (3, 3a-3d) captured thus, - at least one visual range (V, V'), as a region of the measurement surroundings (3, 3a-3d) surveyable (22, 22') from a position (P1-P3) of the coordinate measuring device (1) adopted within the scope of the movement, is ascertained automatically on the basis of the measurement surroundings (3, 3a-3d) captured thus, - the position (P1-P3) is checked for the suitability thereof for a deployment, in particular for a second and next deployment, on the basis of an automatic combined analysis (23, 23') of the measurement region (M, M'), the task region (O, O') and the visual range (V, V').

2. Method according to Claim 1, characterized in that the optical capture (40) of the measurement surroundings (3, 3a-3d) is implemented continuously, wherein - the task region (O, O') is updated continuously on the basis of the continuously captured measurement surroundings (3, 3a-3d) and / or - the check for the suitability for a deployment is likewise implemented continuously.

3. Method according to Claim 1 or 2, characterized in that the optical capture (40) of the measurement surroundings (3, 3a-3d) is implemented - measuring beam-based by means of profiling and / or coarse scanning and / or - photographically by means of a panoramic image recording, stereo-photogrammetry, a depth image recording, a range image camera and / or an overview camera of the coordinate measuring device (1).

4. Method according to any one of the preceding claims, characterized in that the automatic combined analysis (23, 23') contains checking for overlaps of, and / or gaps in, the measurement region (M, M'), task region (O, O') and / or visual range (V, V').

5. Method according to Claim 4, characterized in that the presence of gaps or overlaps is ascertained on the basis of point correspondences between the regions / ranges (M, M', O, O', V, V'), wherein - a gap is ascertained on the basis of points in the task region (O, O') that have no correspondences in the visual range (V, V') and / or - point correspondences are ascertained on the basis of point spacings, and / or - point correspondences are ascertained on the basis of a comparison and / or a tracking of local image features.

6. Method according to any one of the preceding claims, characterized in that a user warning is output within the scope of the method as soon as the position (P3) is determined as being unsuitable (25b) for a deployment.

7. Method according to any one of the preceding claims, characterized in that, within the scope of the method and on the basis of a result (24) of the check, - a suitable and / or unsuitable location (P1-P3) and / or location zone for surveying a further measurement region - and / or existing or potential coverage gaps in the task region (O, O') are established and provided as user output.

8. Method according to any one of the preceding claims, characterized in that ascertaining a suitable position (P1-P3) for an optimal deployment is further implemented on the basis of at least one specified optimization criterion.

9. Method according to Claim 8, characterized in that the optimization criterion relates to - gap-free joining of a further measurement region to the first measurement region (M, M') with a defined overlap with said first measurement region (M, M') and / or - surveying the task region (O, O') with as few deployments as possible and / or as little time expenditure as possible and / or the shortest possible path (4) between the deployments and / or the greatest possible geometric accuracy of the deployments with respect to one another.

10. Method according to Claim 8 or 9, characterized in that the optimization criterion relates to - an angle of incidence of the measuring beam (5) on object surfaces (50) and / or - a resolution of the coordinate measurement.

11. Method according to any one of the preceding claims, characterized in that within the scope of - the optical capture of measurement surroundings (3, 3a-3d), there is identification of objects, and / or - the ascertainment of the task region (O, O'), there is filtering of objects and / or regions of the surroundings that should not be surveyed.

12. Method according to any one of the preceding claims, characterized in that the movement and the surveying of a further measurement region from a position (P1, P2) ascertained as suitable for a further deployment are implemented automatically should an independently mobile coordinate measuring device (1) be present.

13. Method according to any one of the preceding claims, characterized in that the optical capture of measurement surroundings (3, 3a-3d) is implemented using - simultaneous localization and mapping, LIDAR-simultaneous localization and mapping, structure from motion and / or dense matching algorithms, more particularly based on deep learning, and / or - additionally captured data from at least one position, direction and / or acceleration sensor of the coordinate measuring device (1).

14. Computer program product having program code stored on an electronic data processing unit, configured as a control and evaluation unit of a terrestrial optoelectronic coordinate measuring device (1), for carrying out at least the following steps of the method according to Claim 1: - automatically optically capturing (40) measurement surroundings (3, 3a-3d) within the scope of changing the deployment of the coordinate measuring device (1), - ascertaining (21, 21') at least one task region (O, O'), as a region of the measurement surroundings (3, 3a-3d) to be surveyed, on the basis of the measurement surroundings (3, 3a-3d) captured thus, - ascertaining (22, 22') at least one visual range (V, V'), as a region of the measurement surroundings (3, 3a-3d) surveyable from a position (P1-P3) of the coordinate measuring device (1) adopted within the scope of the movement, on the basis of the measurement surroundings (3, 3a-3d) captured thus, - checking the position (P1-P3) for the suitability thereof for a deployment on the basis of a combined analysis (23, 23') of a measurement region (M, M') surveyed from a first deployment (41), the task region (O, O') and the visual range (V, V').

15. Terrestrial optoelectronic coordinate measuring device (1) embodied for measuring beam-based determination of object coordinates, characterized in that the coordinate measuring device (1) comprises - one or more optical units, embodied to capture measurement surroundings (3, 3a-3d) and - a deployment checking functionality, wherein the following is implemented automatically when carrying out the deployment checking functionality: - providing a measurement region (M, M') as an already surveyed region of the measurement surroundings (3, 3a-3d), - automatically optically capturing (40) the measurement surroundings (3, 3a-3d) by means of the one or more optical units within the scope of changing the deployment of the coordinate measuring device (1) within the measurement surroundings (3, 3a-3d), - ascertaining (21, 21') at least one task region (O, O'), as a region of the measurement surroundings (3, 3a-3d) to be surveyed, on the basis of the measurement surroundings (3, 3a-3d) captured thus, - ascertaining (22, 22') at least one visual range (V, V'), as a region of the measurement surroundings (3, 3a-3d) surveyable from a position of the coordinate measuring device (1) adopted within the scope of the movement, on the basis of the measurement surroundings (3, 3a-3d) captured thus, - checking the position (P1-P3) for the suitability thereof for a deployment on the basis of a combined analysis (23, 23') of the measurement region (M, M'), the task region (O, O') and the visual range (V, V').