Method for identifying measuring points in an optical measuring system

• US 20040027589A1
• Filed: 06/12/2003
• Published: 02/12/2004
• Est. Priority Date: 09/11/2000
• Status: Active Grant

• Current Assignee: Leica Geosystems AG (Hexagon AB)
• Original Assignee: Leica Geosystems AG (Hexagon AB)
• Inventors: Clarke, Timothy Alan, Wang, Xinchi
• Granted Patent: US 7,184,151 B2
• Time in Patent Office: Days
• US Class Current: 356/620
• CPC Class Codes: G01B 11/00 Measuring arrangements characterised by the use of optical techniques
• CPC Class Codes: G01C 11/00 Photogrammetry or videogrammetry, e.g. stereogrammetry; Photographic surveying
• CPC Class Codes: G01C 15/02 Means for marking measuring points

Abstract

In an optical measuring system for e.g. determining spatial position and orientation of objects a plurality of measuring points on the object is registered by cameras, laser measuring devices or a combination thereof. For identifying the measuring points, one target of a specific intensity and/or size or a predetermined pattern (3) of a plurality of targets (4) having specific differing intensities and/or sizes is associated to each measuring point. The intensities and/or sizes of the targets are detected e.g. in a pixel image of the target (4) by summing up intensities sensed by pixels being comprised in the image of the target. The targets are e.g. light emitting means consuming differing amounts of energy, reflecting, black or white spots of differing diameter or spots of differing shades of gray or other suitable color. Three to five grades of intensity and/or size can be realized easily. The advantage compared with known binary segment or dot codes used for measuring point identification in optical measuring systems is the fact that in systems with a small amount of measuring points one target per measuring point is sufficient and that when using patterns (3) of targets (4) each target can be used as measuring point and can supply in addition to identification information further useful information.

Claims

1. Method for identification of measuring points in an optical measuring system in which system a plurality of active or passive targets is used for marking measuring points, characterized in that one or a plurality of targets (4, 10) is associated to each measuring point, the targets having differing intensities and/or differing sizes and that for identification of the measuring points the intensities and/or sizes of the targets (4, 10) are registered.

2. Method according to claim 1, characterized in that the targets (4, 10) are imaged in pixel images (1) and that intensities and/or sizes of the pixel images (1) are determined by summing-up intensities (I_i) sensed by pixels (P_i) comprised in the image (1) of a target, by counting the pixels (P_i) comprised in the image (1) of a target or by determining the maximum intensity (I_M) sensed by one of the pixels (P_M) comprised in the image (1) of a target.

3. Method according to one of claims 1 or 2, characterized in that the targets (10) are light emitting means emitting differing amounts of light energy.

4. Method according to one of claims 1 or 2 characterized in that the targets (4) are light reflecting spots or white spots on black background or black spots on white background and that the spots have differing sizes.

5. Method according to one of claims 1 or 2 characterized in that the targets are spots of differing shades of gray on a white or black background or spots of differing intensity of at least one color.

6. Method according to one of claims 1 to 5 characterized in that to each measuring point one target is associated and that the measuring point identity is encoded by the specific intensity and/or size of the target associated with the measuring point.

7. Method according to one of claims 1 to 5, characterized in that to each measuring point a plurality of targets (4, 10) is associated, the plurality of targets (4, 10) being arranged in a predetermined pattern (3) and that the measuring point identity is encoded by specific intensities and/or sizes of the targets (4, 10) in the pattern (3).

8. Method according to claim 7, characterized in that for computing the spatial position and/or orientation of a measuring point, the spatial position of the targets (4, 10) in the target pattern (3) associated with the measuring point are determined.

9. Set of arrangements of a plurality of targets (4, 10) each serving for identifying measuring points in an optical measuring system, characterized in that the targets (4, 10) of each arrangement are arranged in the same pattern (3) or in differing patterns and that the targets (4, 10) have differing intensities and/or sizes.

10. Set of arrangements according to claim 9, characterized in that the target pattern (3) is a circle.

11. Set of arrangements according to one of claims 9 or 10, characterized in that the targets (10) are light emitting means emitting differing amounts of light energy.

12. Set of arrangements according to one of claims 9 or 10, characterized in that the targets (4) are light reflecting spots of differing sizes.

13. Set of arrangements according to one of claims 9 or 10, characterized in that the targets (4) are black spots on a white background or white spots on a black background and have differing sizes.

14. Set of arrangements according to one of claims 9 or 10, characterized in that the targets are spots of differing gray shades on a white or black background or spots of at least one specific color in differing intensities.