Scanning method and surveying system with scanning functionality

Patent metadata

Field	Value
Publication number	US-10222476-B2
Application number	US-201615147889-A
Country	US
Kind code	B2
Filing date	May 5, 2016
Priority date	May 8, 2015
Publication date	Mar 5, 2019
Grant date	Mar 5, 2019

Abstract

In some embodiments a scanning method for deriving information about surfaces of objects for a surveying system is disclosed. In some embodiments, the surveying system may include a control and evaluation unit with scanning functionality, such as, for example, a laser scanner or a total station. In some embodiments, the recorded point set of the detected object points is kept available in a volatile memory of the control and evaluation unit and by means of the control and evaluation unit as part of the scanning process an adaptation of the recorded point set is effected depending on at least one point density of the recorded point set. The adapted point set generated thereby, with loss of the recorded point set, is stored in a permanent memory.

First claim

What is claimed is:

1. A scanning method for deriving information about surfaces of objects for a surveying system with scanning functionality comprising a control and evaluation unit, wherein a first recording of a point set composed of object points detected by means of a measurement beam of the surveying apparatus is effected by means of a scanning process comprising:
scanning objects by continuously changing the alignment of the measurement beam in accordance with a known first scanning pattern and first scanning region,
determining the respective distance to the object point and the respective alignment of the measurement radiation emitted for a distance measurement, wherein:
the recorded point set of the detected object points is kept available in a volatile memory of the control and evaluation unit and prior to storage in a permanent memory by means of the control and evaluation unit as part of the scanning process an adaptation of the recorded point set is effected depending on at least one point density of the recorded point set, as a result of which an adapted point set is generated, and, along with final loss of the recorded point set, only the adapted point set is stored in the permanent memory,
wherein ascertaining at least one point density indicator for the recorded point set is effected on the basis of the determined distances and alignments and the adaptation is effected depending on the point density indicator.

2. The method according to claim 1 , wherein:
the adaptation is effected by the point density itself being adapted within at least one predetermined partial region of the scanning region in accordance with predetermined selection criteria.

3. The method according to claim 1 , wherein:
ascertaining the point density indicator is effected during the scanning process in real time in relation to object points already detected and/or
the point density indicator is based on estimated spatial distances of detected object points.

4. The method according to claim 3 , wherein:
the adaptation is effected in such a way that on the basis of the point density indicator a check is made point by point or region by region to establish whether a previously defined maximum value for the point density is exceeded and, in the case of the maximum value being exceeded, the point density is reduced by means of thinning out or averaging in relation to the corresponding point or region.

5. The method according to claim 3 , wherein:
the adaptation is effected in such a way that on the basis of the point density indicator a check is made point by point or region by region to establish whether a previously defined maximum value for the point density is exceeded and, in the case of the maximum value being exceeded, the point density is reduced.

6. The method according to claim 3 , wherein:
a selection of at least one region of interest (ROI) from the scanning region is effected depending on the point density indicator, wherein in the context of the selection on the basis of the point density indicator a check is made point by point or region by region to establish whether a predetermined minimum point density is present.

7. The method according to claim 1 , wherein:
determining a neighborhood set representing neighboring object points is effected in the context of ascertaining the point density indicator.

8. The method according to claim 7 , wherein:
on the basis of the neighborhood set object surfaces and associated surface normals are estimated and the surface normals are used for ascertaining the point density indicator.

9. The method according to claim 1 , wherein:
an information gain indicator for scanned object points is determined, which indicates the gain in information about the surface of a respective object that is obtained by means of the respective object point, wherein
the adaptation is effected depending on the information gain indicator of a respective scanned object point, wherein specifically object points whose information gain indicator exceeds a predetermined threshold value are transferred as part of the adapted point set into the permanent memory, and/or
ascertaining the information gain indicator is effected during the scanning in real time for object points already scanned.

10. The method according to claim 9 , wherein:
the information gain indicator is determined on the basis of the estimated object surfaces.

11. The method according to claim 9 , wherein:
a selection of at least one region of interest (ROI) from the scanning region is effected depending on the information gain indicator, wherein in the context of the selection on the basis of the information gain indicator a check is made point by point or region by region to establish whether the respective information gain indicator exceeds a predetermined threshold value.

12. The method according to claim 11 , wherein:
for the region of interest (ROI) the recorded point set is adapted by increasing the point density within the region of interest (ROI).

13. The method according to any one of claim 11 , wherein:
a second recording is effected in accordance with a second scanning pattern and second scanning region, wherein
the second scanning region is defined depending on the region of interest (ROI), the second scanning pattern is closer-meshed than the first scanning pattern, and the object points recorded in this case are taken into account in the adaptation of the recorded point set.

14. The method according to claim 9 , wherein:
the information gain indicator is determined on the basis of the estimated object surfaces depending on a variance of normal distances of object points of a neighborhood set with respect to the object surface estimated with respect thereto.

15. The method according to claim 1 , wherein:
the recorded point set is divided into individual point sets and the adaptation is effected for each of the individual point sets.

16. The method according to claim 1 , wherein:
the quality of the measurement values of a respective object point is taken into account in the adaptation.

17. The method according to claim 1 , wherein:
the quality of the signal-to-noise ratio of the distance determined of a respective object point is taken into account in the adaptation.

18. The method according to claim 1 , wherein the surveying system comprises a laser scanner or a total station.

19. The method according to claim 1 , wherein:
the adaptation is effected by the point density itself being reduced by thinning out and/or averaging within at least one predetermined partial region of the scanning region in accordance with predetermined selection criteria.

20. A non-transitory computer program product, stored on a machine-readable carrier, comprising program code suitable for carrying out the method according to claim 1 .

21. A surveying system with scanning functionality, the surveying system comprises a control and evaluation unit configured to
scan objects by continuously changing the alignment of the measurement beam in accordance with a known first scanning pattern and first scanning region,
determine the respective distance to the object point and the respective alignment of the measurement radiation emitted for a distance measurement, wherein:
the recorded point set of the detected object points is kept available in a volatile memory of the control and evaluation unit and prior to storage in a permanent memory by means of the control and evaluation unit as part of the scan

Assignees

• Leica Geosystems Ag

Inventors

• Herbst Christoph
• Spettel Patrick

Classifications

• G06T1/0007 Primary

  Image acquisition · CPC title

• G01S7/4817

  relating to scanning · CPC title

• G01S7/4808

  Evaluating distance, position or velocity data · CPC title

• G06T2200/04

  involving 3D image data · CPC title

• G01C15/002

  Active optical surveying means (optical plumbing G01C15/105) · CPC title