Scanning survey device

Abstract

The invention relates to a scanning surveying device. A theodolite or a total station or a laser tracker having a scanning function, an alidade rotating about a vertical axis, and a telescope unit (4) having a beam outlet for a laser measuring beam (6), the telescope unit (4) being mounted on the alidade (2) and being movable in the form of a tilting movement about a pitch axis (5). The pitch axis (5) is substantially orthogonal to the vertical axis (3). The scanning function comprises a scanning sequence according to the angular velocity of the alidade (2) about the vertical axis (3), wherein during the scanning sequence, the alidade (2) performs a continuous rotational movement about the vertical axis (3) at a substantially constant angular velocity, and the angular velocity of the alidade (2) is faster than half the angular velocity of the tilting movement of the telescope unit (4) about the pitch axis (5), in particular, the angular velocity of the alidade (2) is faster than the angular velocity of the tilting movement of the telescope unit.

Description

Technical Field

[0001] The present invention relates to a scanning surveying device, which is configured as a theodolite or a total station or a laser tracker having an alidade and a telescope. The alidade can rotate around a vertical axis, and the telescope is mounted on the alidade and can be tilted around an elevation axis. The telescope comprises a beam outlet for a laser ranging beam. The elevation axis is substantially orthogonal to the vertical axis. Background Art

[0002] In order to align the ranging beam on the target, both the alidade and also the telescope are usually moved, wherein at least one movement of the alidade or the telescope is necessary for a particular surveying task. The alidade and the telescope are usually relatively heavy, so that surveying tasks with oscillating movements of the alidade and the telescope are energy-consuming and / or slow.

[0003] The time consumption can be reduced by limiting the size of the area where the distance measurement is performed. This limitation does not significantly reduce the number of oscillation movements and therefore does not sufficiently reduce the energy consumption.

[0004] Energy consumption can be reduced when performing a scan by rotating the alidade and the telescope at a constant rotational speed each. Energy is used for acceleration and braking at the beginning and end of the scanning task. According to the prior art, the telescope weighs less than the alidade, so the telescope rotates at a higher rotational speed than the alidade. For a full dome scan, the alidade is rotated at a low constant speed or in steps over at least half a turn (200 gon, 180°).

[0005] Scanning tasks performed with a fast rotating telescope and a slower rotating alidade have an uneven grid, where the density of distance measurements in the zenith region and the nadir region is high. For most scanning tasks, these regions are of little interest. The total scanning time and effort spent on acquiring interesting measurement points, for example in the equatorial region, is high. Therefore, known scanning with a fast rotating telescope and a slower rotating alidade cannot sufficiently reduce the time consumption of the scanning task.

[0006] EP 3 450 915 A1 discloses a solution for increasing the scanning rate. According to this solution, the telescope has an additional fast deflection element to quickly deflect the outgoing distance measuring beam relative to the telescope. This fast deflection of the distance measuring beam is used for measurements carried out within a specific acquisition area.

[0007] However, in order to scan a given acquisition area, the alidade and the telescope must also be moved. The alidade and the telescope must be driven with the speed and acceleration required for a path sufficient to cover the acquisition area. The path covering the acquisition area must have curves that keep the path within the area. At least at some of these curves, the alidade and / or the telescope must brake or accelerate its movement, and therefore must consume energy and time. Summary of the invention

[0008] The object of the present invention is therefore to find a theodolite or a total station or a laser tracker for scanning a defined acquisition area with low energy and time consumption and preferably with an optimal measurement point density.

[0009] The present invention relates to an industrial or geodetic surveying device configured as a theodolite or a total station or a laser tracker comprising:

[0010] a base, which defines a vertical axis,

[0011] an alidade, which is mounted on a base and can be rotated about a vertical axis by a motor,

[0012] a telescope unit comprising a beam exit for a laser measuring beam defining a target axis, the telescope unit being mounted on the alidade and movable in a motor-driven manner in the form of a tilting movement relative to the alidade about an elevation axis, the elevation axis being substantially orthogonal to the vertical axis,

[0013] a distance measuring unit configured to generate a laser measurement beam and to provide distance measurement data for determining the distance to the object based on the laser measurement beam, wherein the laser measurement beam extends from the telescope unit along a target axis,

[0014] an angle determination unit configured to provide angle determination data for determining an orientation of the alidade relative to the base and an orientation of the telescope unit relative to the alidade, respectively, and

[0015] A control unit configured to automatically control a scanning function of the surveying device, the scanning function comprising generating distance measurement data and angle determination data for different scanning points set by rotating the collimator about the vertical axis and by tilting the telescope unit about the elevation axis, respectively.

[0016] The industrial or geodetic surveying device of the invention is characterized in that

[0017] The scanning function comprises a scanning sequence according to an angular velocity of the collimator about a vertical axis, wherein during the scanning sequence, i.e. at least for a major part of a time window of the scanning sequence,

[0018] The alidade is continuously rotated about the vertical axis at a uniform, in particular mainly constant, angular velocity, and

[0019] The angular velocity of the alidade about the vertical axis is faster than half the angular velocity of the tilting movement of the telescope unit about the elevation axis, in particular faster than the angular velocity of the tilting movement of the telescope unit.

[0020] A uniform, in particular constant, angular velocity of the continuously rotating alidade is relevant for minimum energy consumption. In a typical total station, the moment of inertia of the alidade is higher than that of the telescope unit and the rotational friction of the alidade is lower than the kinetic friction of the telescope unit. Therefore, if the alidade rotates at a uniform velocity that is higher than the velocity of the tilting motion of the telescope unit, the power consumption is reduced.

[0021] The vertical axis is used to perform most of the movements during scanning, so it is called the main axis. In the prior art solutions of scanning total stations, the pitch axis is the main axis. Changing the main axis to the vertical axis and rotating the collimator at a constant angular velocity will reduce the time consumption.

[0022] That is, during the scanning sequence, the uniform angular velocity of the continuously rotating alidade is selected to be constant or to vary only slightly during a large part of the duration of the scanning sequence. For example, during at least half of the duration of the scanning sequence, the angular velocity of the continuously rotating alidade is selected to have a maximum variation of ±10%.

[0023] In a preferred embodiment, the rotational direction of the tilting movement of the telescope is constant during the scanning sequence, at least in a general trend.

[0024] The density of the measuring points on the unit sphere centered at the intersection of the vertical axis and the pitch axis depends on the path of the projection of the measuring beam on the unit sphere and on the triggering of the distance measurement. The collimator rotates around the vertical axis at a constant angular velocity, and the tilting movement of the telescope unit around the pitch axis has an angular velocity around the pitch axis that is less than the angular velocity of the collimator around the vertical axis.

[0025] Therefore, a small section of the path of the projection of the measurement beam on the unit sphere has a longer component around the vertical axis than around the pitch axis. As the distance from the vertical axis becomes shorter, the length of the section of such a path extending within a given angle around the vertical axis becomes shorter and shorter. In the equatorial region of the unit sphere, the sections of such a path extending within a given angle around the vertical axis have similar lengths. The measurement points projected onto the unit sphere are evenly distributed in the equatorial region. The tilting movement of the telescope unit around the pitch axis controls the gaps between adjacent measurement points on consecutive turns of the path around the vertical axis.

[0026] If density differences in the measuring points must be prevented, the number of measuring points on the path segments extending within a given angle around the vertical axis and having different lengths should have the number of measuring points corresponding to the specific length of the segment. This means that towards the vertical axis there should be fewer measuring points on these segments, since the length of these segments within the same angle around the vertical axis is shorter.

[0027] A high density of measuring points close to the vertical axis and at the zenith or nadir region can be prevented by preventing paths close to the vertical axis or by reducing the triggering frequency of distance measurement if the measuring beam and the target axis are moved towards the vertical axis, respectively.

[0028] In a preferred embodiment the control unit is configured to coordinate the angular velocity of the rotational movement of the alidade, the tilting movement of the telescope unit and the distance measuring unit in such a way that in projection onto the surface of a sphere around the surveying device a grid with uniform point spacing is generated.

[0029] The distance measuring unit can respectively carry out the distance measurement with a constant triggering frequency or trigger the distance measurement by a parameter which depends on the alignment of the laser measuring beam with the target axis.

[0030] In a preferred embodiment, the movement of the telescope prevents the path from approaching the vertical axis and approaching the zenith region or the nadir region, respectively. This can be done by limiting the tilting movement of the telescope unit around the pitch axis to no full circle upward and / or downward movement. Due to this limitation, the laser measurement beam extending from the telescope unit along the target axis is never parallel to the vertical axis and does not hit the unit sphere close to the vertical axis. In the equatorial region of the unit sphere, the length of the path circle around the vertical axis varies very little. Therefore, in the equatorial region, the point density generated at a constant trigger frequency shows only small changes as the angle around the pitch axis changes.

[0031] In another preferred embodiment, the scanning function comprises: the telescope unit is moved about the pitch axis so that in the projection onto the sphere around the surveying device the target axis follows a trajectory that spirals about the vertical axis. Constant rotation of the collimator and upward and / or downward movement of the telescope without a full circle generates a spiral path on the unit sphere. The moment of inertia of the telescope is smaller than the moment of inertia of the collimator and the angular velocity of the tilting movement of the telescope unit about the pitch axis is smaller than the angular velocity of the collimator about the vertical axis. Therefore, the energy required to generate these spiral paths is small.

[0032] The scanning function thus comprises a movement of the telescope unit about the elevation axis such that, in the projection onto the sphere around the surveying device, the target axis follows a trajectory that spirals about the vertical axis.

[0033] During a scanning sequence, the rotational direction of the tilting movement of the telescope is preferably constant, at least in general trend.

[0034] In another preferred embodiment, the scanning function includes:

[0035] a first movement of the telescope unit about the elevation axis from a defined maximum zenith area, in particular the zenith, to a defined maximum nadir area, and / or

[0036] a second movement of the telescope unit about the elevation axis from a defined maximum nadir area to a defined maximum zenith area (in particular the zenith),

[0037] In particular, the sense of rotation of the first movement around the pitch axis is opposite to the sense of rotation of the second movement around the pitch axis.

[0038] An upward and / or downward movement of the telescope that does not make a full revolution prevents the path on the unit sphere from approaching the vertical axis. Instead of moving the path away from the vertical axis, it is also possible to move the measuring beam and the target axis, respectively, closer to the vertical axis with an increasing angular velocity about the elevation axis. A faster angular velocity reduces the number of measuring points on the path section that is close to the vertical axis. This also applies when the trigger frequency of the distance measurement is constant.

[0039] Starting from the zenith, a full dome scan is performed using a downward spiral trajectory and ends when the nadir region covered by the frame is reached. The next spiral can start at the nadir region and move toward the zenith.

[0040] The angular velocity about the pitch axis may be varied in such a way that the path on the unit sphere, when projected onto a plane, has at least a small segment that looks similar to a segment of a Fibonacci spiral. That is, the scanning function may include a continuously varying movement of the telescope unit about the pitch axis such that, in the projection onto the unit sphere about the surveying device, the target axis follows a trajectory having segments that look like segments of a Fibonacci spiral.

[0041] In another preferred embodiment, the movement of the telescope is performed stepwise while the alidade is continuously rotated. This allows distance measurements along a horizontal scan line.

[0042] In another preferred embodiment, the scanning function comprises movement of the telescope unit about the elevation axis such that in a projection onto a sphere about the surveying device the target axis follows a circular trajectory in different spaced apart planes orthogonal to the vertical axis.

[0043] In another preferred embodiment, the scanning function comprises triggering the distance measuring unit to generate distance measurement data as a function of the rotation angle of the telescope about the pitch axis. Thus, the distance measurement is triggered as a function of the elevation angle of the target axis. A maximum frequency trigger will be applied at a horizontal angular alignment of the target axis, where the target axis is perpendicular to the vertical axis. A minimum frequency trigger will be applied at a vertical angular alignment of the target axis, where the target axis is parallel to the vertical axis. The triggering frequency increases with increasing angular distance of the target axis from the vertical axis. The triggering depends on the angular alignment about the pitch axis and allows to have a similar density of measurement points over all areas of a unit sphere centered at the intersection of the vertical and pitch axes, wherein the measurement point is the intersection of the laser measuring beam with the sphere.

[0044] The scanning function thus includes triggering the distance measuring unit to generate distance measurement data as a function of the rotation angle of the telescope about the pitch axis.

[0045] In another preferred embodiment, the coupled movement of the alidade and the telescope is processed as a superposition of two perpendicular oscillations with variable frequency and phase difference. The characteristics of this superposition can be learned from the analysis of Lissajous figures. If the movement frequency of the alidade is ω A The telescope's moving frequency ω T If the ratio is rational, the generated path is closed. A closed path is advantageous for short-time scans where the measurement points are distributed at a low point density within the unit sphere. For irrational ratios, the path is not closed, which is advantageous for fine scans where the measurement points are distributed at a high point density within the unit sphere. In order to cover at least one region of the unit sphere well with the path generated by the measurement beam intersecting the unit sphere, the telescope frequency ω T With the alidade frequency ω A The ratio between must be close to 1, preferably between 5 / 6 and 1. If the phase difference is not an integer multiple of π, the coverage is better. The preferred phase difference is in the range from π / 4 to 3π / 4. A phase difference of π / 2 is particularly advantageous.

[0046] The solution of the invention ensures improved efficiency in terms of scanning time, point density, grid uniformity and power consumption. In addition, the resulting point cloud is smaller due to the uniform point spacing (even in the zenith). Furthermore, the nadir area hidden by the scanning device itself can be excluded from the scanning range. Smaller point clouds and equal grids can better meet the expectations of users and make scanning and post-processing faster.

[0047] With the new concept, the scan time for a full dome scan can be accelerated. A scan trajectory with a uniform but reduced measurement point density can be used for a fast scan preview. Partial scan coverage can be achieved with a strip spanning 400 grads around the vertical axis and the expected range around the pitch axis. The elevation range may border the bottom area or the zenith of the alidade. The elevation range bordering the zenith is useful, for example, for acquiring ceilings. The angular velocity around the vertical axis can be optimized for a given trigger frequency and resolution. Variable trigger frequency and controllable elevation angle allow, for example, high resolution at the equator (high measurement point density) and low resolution at the poles (low measurement point density).

[0048] In a preferred embodiment, the control unit allows the user to select the scanning resolution and the scanning window. The control unit then selects the corresponding scanning mode. Another selection parameter is, for example, an optimization criterion (such as short scanning time or low power consumption or fast preview or moving object suppression). The resulting optimized scanning path is determined and the corresponding control of the angular movement around the vertical axis and the pitch axis and the triggering of the distance measurement are derived. Not all laser types allow external triggering. Some laser sources operate in a self-triggering mode at a certain frequency. This frequency will be taken into account when inferring the angular movement around the vertical axis and the pitch axis.

[0049] For example, moving pedestrians and cars may obscure part of the scan area. A known method to reduce the impact of moving pedestrians and cars is to scan the area twice. Obviously, the scanning time is doubled, and post-processing must be performed to identify and delete the data of unwanted objects.

[0050] The solution of the invention allows to improve the known method by doubling the angular velocity about the vertical axis, resulting in doubling the interval between the measurement points, and by shifting the starting point of the second scan and / or by calculating different scan paths in a way that increases the time between the measurements of adjacent points. Moving objects produce distance measurement points where there are no adjacent distance measurement points with similar values. Inconsistent distance measurements can be ignored, thereby reducing the influence of moving objects. Thus, the influence of moving objects in the scan area can be reduced without the need for special post-processing and additional scan time. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The following is a more detailed description or explanation of the surveying device according to the invention, purely by way of example, with reference to the working examples schematically shown in the accompanying drawings. In the drawings, identical elements are marked with the same reference numerals. The described embodiments are generally not shown true to scale and should not be interpreted as limiting the invention. In particular,

[0052] Figure 1 is a schematic stereogram of a total station according to the prior art, in which a section of a scanning trajectory is visualized on a unit sphere,

[0053] Figure 2 is a schematic perspective view of a total station according to an embodiment of the present invention, in which a segment of a scanning trajectory is visualized on a unit sphere,

[0054] Figure 3 is based on Figure 2 Schematic diagram of a total station with distance measurement points visualized on two indicator areas,

[0055] Figure 4 is based on Figure 2 Schematic diagram of a total station with two segments of two different scanning trajectories visualized on the unit sphere, and

[0056] Figure 5 is a schematic perspective view of a total station according to an embodiment of the present invention, wherein segments of a scanning trajectory are visualized on a unit sphere. DETAILED DESCRIPTION

[0057] Figure 1 A total station 1 according to the prior art is shown, in which an alidade 2 is mounted on a base, not shown, and can be rotated about a vertical axis 3 in a motor-driven manner. A telescope unit 4 is mounted on the alidade 2 and can be moved in a motor-driven manner in the form of a tilting movement about a pitch axis 5. The telescope unit 4 comprises a beam exit for a laser measuring beam 6 for defining a target axis. The pitch axis 5 is approximately orthogonal to the vertical axis 3. According to the prior art, the telescope unit 4 weighs less than the alidade 2 and, for scanning, is rotated at a constant rotation speed that is higher than the rotation speed of the alidade 2. For a full dome scan, the alidade is rotated at least over half a turn (200 grads, 180°).

[0058] A portion of a scanning task with a fast-rotating telescope unit 4 and a slower-rotating alidade 2 is visualized on a unit sphere 7, the center of which is at the intersection of the vertical axis 3 and the elevation axis 5. The intersection of the measuring beam 6 with the unit sphere 7 moves along a path 8. The distance measurement points are generated at a constant trigger frequency and are spaced substantially at equal intervals on the path 8. This equal spacing is due to the fact that the telescope unit 4 rotates much faster than the alidade 2. During each rotation of the telescope unit 4, the measurement path 8 passes through the zenith Z and the nadir N. Therefore, in the region at the zenith Z and the nadir N, the path density and the corresponding measurement point density are very high and are lower in the equatorial region. There is no need to perform a large number of distance measurements and corresponding costly data processing for the measurement points in these regions, because these regions are not of much interest for most scanning tasks. Therefore, the known scanning with a fast-rotating telescope unit 4 and a slowly rotating alidade 2 cannot sufficiently reduce the time consumption of the scanning task.

[0059] Figure 2 An embodiment of the total station 1 of the invention is shown, in which the alidade 2 is mounted on a base, not shown, and can be rotated about a vertical axis 3 in a motor-driven manner. A telescope unit 4 is mounted on the alidade 2 and can be moved in a motor-driven manner in the form of a tilting movement about a pitch axis 5. The telescope unit 4 comprises a beam exit for a laser measuring beam 6 defining a target axis. The pitch axis 5 is approximately orthogonal to the vertical axis 3. The alidade 2 rotates at a rotation speed that is higher than the rotation speed of the telescope unit 4.

[0060] A part of the scanning task with the rapidly rotating alidade 2 and the slower rotating telescope unit 4 is visualized on a unit sphere 7, wherein the center of the unit sphere 7 is at the intersection of the vertical axis 3 and the elevation axis 5. The intersection of the measuring beam 6 with the unit sphere 7 moves along a path 8. The constant rotation of the alidade 2 and the upward and / or downward movement of the telescope unit 4 generate a spiral path 8 on the unit sphere 7. The telescope unit 4 has a smaller moment of inertia than the alidade 2, and the angular velocity of the tilting movement of the telescope unit 4 about the elevation axis 5 is smaller than the angular velocity of the alidade 2 about the vertical axis.

[0061] The component of a small section of the path 8 about the vertical axis is longer than the component about the pitch axis. The length of the section of the path 8 extending within a given angle about the vertical axis becomes shorter and shorter with a shorter distance from the vertical axis and an increasing angle to the equator, respectively. In the equatorial region of the unit sphere 7, the sections of the path 8 extending within a given angle about the vertical axis have similar lengths. The measurement points projected onto the unit sphere are then uniformly distributed in the equatorial region. The tilting movement of the telescope unit 4 about the pitch axis 5 controls the gaps between adjacent measurement points on consecutive turns of the path 8 about the vertical axis 3.

[0062] Figure 3 An embodiment of the total station 1 of the invention is shown, in which the measuring points 11 have a more or less identical density in the equatorial region 9 and in the zenith region 10. This is due to the fact that the distance measurement is triggered as a function of the elevation angle of the measuring beam 6 and thus of the angular alignment of the measuring beam 6 about the elevation axis 5. The maximum frequency triggering is applied at the horizontal angular alignment of the measuring beam, where the target axis is perpendicular to the vertical axis. The minimum frequency triggering is applied at the vertical angular alignment of the measuring beam, where the target axis is parallel to the vertical axis 3. The triggering frequency increases with increasing angular distance of the measuring beam from the vertical axis. This triggering depends on the angular alignment about the elevation axis 5 and allows a similar density of measuring points over all regions of the unit sphere 7.

[0063] The scanning function thus comprises triggering the distance measuring unit to generate distance measurement data as a function of the rotation angle of the telescope unit 4 about the elevation axis 5 .

[0064] Figure 4 The embodiment of the total station 1 of the present invention is shown. The total station 1 has the following Figure 2 Function for generating two spiral paths 8 and 8' is shown. The turns of the two paths 8 and 8' are offset from each other in such a way that the measurement points from both paths 8 and 8' are evenly distributed over at least a portion of the unit sphere 7. The paths 8 and 8' shown are both generated with the telescope unit 4 rotating in the same angular direction. If the paths 8 and 8' are generated with the telescope unit 4 rotating in opposite angular directions around the elevation axis and the collimator 2 continuously rotating in the same angular direction around the vertical axis, the paths 8 and 8' will have an intersection point. The density of measurement points at the intersection point of the paths with the intersection point will be higher than the density of measurement points at a distance from the intersection point.

[0065] Figure 5 An embodiment is shown with a special scanning function which combines a continuous rapid rotation of the alidade 2 about the vertical axis 3 and a variable angular velocity of the rotating telescope unit 4, wherein the scanning sequence is limited to time intervals within which the angular velocity of the rotational movement of the alidade 2 is faster than the angular velocity of the tilting movement of the telescope unit 4 about the elevation axis 5. During the scanning sequence, the component of the path 8 about the vertical axis is longer than the component about the elevation axis, which is the case for a measurement area extending from the equator towards the zenith and nadir. In this measurement area, distance measurements are made on the path 8, so that the measurement points are located in this area. The angular velocity about the elevation axis can be varied in such a way that the path on the unit sphere has segments which look similar to segments of a Fibonacci spiral when projected onto a plane.

[0066] In two movement regions extending from the zenith end and the nadir end of the measurement area, the angular velocity of the telescope unit 4 is higher than the angular velocity of the collimator 2, and the path 8 passes through the zenith and the nadir. In the movement region, the path 8 takes a shortcut to reach another part of the measurement area. Directly continuous path segments in the measurement area have opposite components around the pitch axis. Therefore, alternatively, measurements are made on path segments pointing to the zenith and the nadir, respectively, wherein these segments are also offset in the direction around the vertical axis. This allows to have measurement points on completely different parts of the unit sphere within a very short time interval. In the movement regions around the zenith and the nadir, measurements will not be possible due to the increased path density.

[0067] Although the present invention has been described above in part with reference to some preferred embodiments, it must be understood that various modifications and combinations of the different features of the described embodiments are possible. All these modifications are within the scope of the appended claims.

Claims

1. An industrial or geodetic surveying device (1), the industrial or geodetic surveying device (1) being constructed as a theodolite or a total station or a laser tracker having the following items: • a base defining a vertical axis (3), • an alidade (2) mounted on the base and rotatable about the vertical axis (3) in a motor-driven manner, • a telescope unit (4) comprising a beam exit for a laser measuring beam (6) for defining a target axis, the telescope unit (4) being mounted on the alidade (2) and being movable in a motor-driven manner in the form of a tilting movement relative to the alidade (2) about an elevation axis (5), the elevation axis (5) being orthogonal to the vertical axis (3), • a distance measuring unit configured to generate the laser measurement beam (6) and to provide distance measurement data for determining the distance to an object based on the laser measurement beam (6), wherein The laser measurement beam (6) extends from the telescope unit (4) along a target axis, • an angle determination unit configured to provide angle determination data for determining the orientation of the alidade (2) relative to the base and the orientation of the telescope unit (4) relative to the alidade (2), respectively, and • a control unit configured to automatically control a scanning function of the surveying device (1), the scanning function comprising: generating distance measurement data and angle determination data for different scanning points (11) respectively set by rotating the alidade (2) about the vertical axis (3) and by tilting the telescope unit (4) about the elevation axis (5), It is characterized in that The scanning function comprises at least one scanning sequence, in which the alidade (2) performs a plurality of consecutive rotations around the vertical axis (3), wherein during the scanning sequence, • the alidade (2) performs continuous rotational motion around the vertical axis (3) at a constant angular velocity, and • the angular velocity of the alidade (2) about the vertical axis (3) is faster than half the angular velocity of the tilting movement of the telescope unit (4) about the elevation axis (5), and • The trigger frequency of the distance measurement increases as the angular distance of the laser measuring beam (6) from the vertical axis (3) increases.

2. The surveying device (1) according to claim 1, It is characterized in that The control unit is configured to coordinate the angular velocity of the alidade (2), the tilting movement of the telescope unit (4) and the distance measuring unit in such a way that a grid with uniform point spacing is generated in the projection onto the surface of a unit sphere (7) around the surveying device (1).

3. The surveying device (1) according to claim 1 or 2, It is characterized in that The scanning function comprises triggering the distance measuring unit to generate the distance measurement data according to the rotation angle of the telescope unit (4) around the pitch axis (5).

4. The surveying device according to claim 1, It is characterized in that The scanning function comprises: the telescope unit (4) moves about the elevation axis (5) so that in a projection onto a unit sphere (7) around the surveying device (1), the target axis follows a trajectory that spirals around the vertical axis (3).

5. The surveying device according to claim 1, It is characterized in that The scanning function comprises: the telescope unit (4) is moved about the elevation axis (5) so that, in a projection onto a unit sphere (7) about the surveying device (1), the target axis follows a circular trajectory in different spaced-apart planes orthogonal to the vertical axis (3).

6. The surveying device according to claim 4, It is characterized in that During the scanning sequence, the rotation direction of the tilting movement of the telescope unit (4) is constant at least in general trend.

7. The surveying device according to claim 6, It is characterized in that The scanning functions include: • a first movement of the telescope unit (4) about the elevation axis (5) from a defined maximum zenith area to a defined maximum nadir area, and / or • A second movement of the telescope unit (4) about the elevation axis (5) from a defined maximum nadir area to a defined maximum zenith area.

8. The surveying device according to claim 1, It is characterized in that The scanning function comprises a continuously variable movement of the telescope unit (4) about the elevation axis (5) so that, in a projection onto a unit sphere (7) about the surveying device (1), the target axis follows a trajectory having segments that look like segments of a Fibonacci spiral.

9. The surveying device according to claim 1, It is characterized in that The angular velocity of the collimator (2) about the vertical axis (3) is faster than the angular velocity of the tilting movement of the telescope unit (4).

10. The surveying device according to claim 7, It is characterized in that The defined maximum zenith area is the zenith (Z).

11. The surveying device according to claim 7, It is characterized in that The rotation direction of the first movement around the pitch axis (5) is opposite to the rotation direction of the second movement around the pitch axis (5).

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