Method and an apparatus for the determination of the 3D coordinates of an object

1. A method for the determination of the 3D coordinates of an object ( 2 ), comprising the steps of:

(I) controllably projecting a fringe pattern onto the object ( 2 ) by an imaging element in a pixel-by-pixel manner,

(II) iteratively determining the local reflectivity of the object;

(III) iteratively adapting the brightness of the fringe pattern of the object; and

(IV) recording and evaluating the light reflected by the object ( 2 ),

wherein said step (II) of iteratively determining the local reflectivity of the object; and said step (III) of iteratively adapting the brightness of the fringe pattern are performed by:

(a) taking a course 3D measurement of the object without an adapted projection pattern;

(b) determining a fringe projection pattern using a brightness distribution adapted to the determined object brightness;

(c) performing a precise 3D measurement of the object using an adapted projection pattern whose brightness is locally adapted to the object reflectivity; and

(d) repeating steps (b) and (c) to increase the precision of the 3D measurement.

2. A method in accordance with claim 1 , wherein the fringe pattern is projected onto the object by an LCOS display, a mirror array or an LCD display.

3. A method in accordance with claim 1 , wherein the light of the light source ( 4 ) for the generation of the fringe pattern is supplied to the object ( 2 ) via a liquid light conductor ( 5 ).

4. A method in accordance with claim 1 , wherein the recorded image data are intermediately stored in a camera memory and are subsequently forwarded for evaluation.

5. A method in accordance with claim 1 , wherein a triangulation base and/or the triangulation angle are variable.

6. A method in accordance with claim 1 , wherein the determination of the reflectivity of the object ( 2 ) and the adaptation of the brightness of the fringe pattern take place iteratively.

7. A method in accordance with claim 1 , further comprising the steps of:

comparing the determined 3D coordinates of the object ( 2 ) with the desired 3D coordinates of the lens; and

projecting the shape deviation onto the object ( 2 ).

8. A method in accordance with claim 7 , wherein the shape deviation is projected onto the object in a false color representation.

9. An apparatus for the determination of the 3D coordinates of an object ( 2 ) having a projector ( 1 ) for the projection of a fringe pattern onto the object ( 2 ), one or more cameras ( 3 ) for the recording of the light reflected by the object and an evaluation device for the evaluation of the recorded images, wherein the projector ( 1 ) includes:

an imaging element for the controllable projection of the fringe pattern onto the object ( 2 ) in a pixel-by-pixel manner,

means for iteratively determining the local reflectivity of the object;

means for iteratively adapting the brightness of the fringe pattern to determine a local reflectivity of the object; and

means for recording and evaluating the light reflected by the object ( 2 ),

wherein said means for iteratively determining the local reflectivity of the object; and said means for iteratively adapting the brightness of the fringe pattern to determine local reflectivity of the object are performed by:

(a) taking a course 3D measurement of the object without an adapted projection pattern;

(b) determining a fringe projection pattern using a brightness distribution adapted to the determined object brightness;

(c) performing a precise 3D measurement of the object using an adapted projection pattern whose brightness is locally adapted to the object reflectivity; and

(d) repeating steps (b) and (c) to increase the precision of the 3D measurement.

10. An apparatus in accordance with claim 9 , wherein the projector ( 1 ) has an LCOS display, a mirror array and/or an LCD display for the projection of the fringe pattern onto the object ( 2 ).

11. An apparatus in accordance with claim 9 , additionally comprising a light source ( 4 ) and a liquid light conductor ( 5 ) for the supply of the light to the projector ( 1 ).

12. An apparatus in accordance with claim 9 , wherein the camera ( 3 ) has a camera memory for the intermediate storage of the recorded image data.

13. An apparatus in accordance with claim 9 , wherein a triangulation base and/or the triangulation angle are variable.

14. An apparatus in accordance with claim 9 , wherein the determination of the reflectivity of the object and the adaptation of the brightness of the fringe pattern take place iteratively.

15. An apparatus in accordance with claim 9 , additionally comprising a device for the comparison of the determined 3D coordinates of the object ( 2 ) with the desired 3D coordinates of the object and for the projection of the shape deviation onto the object ( 2 ).

16. An apparatus in accordance with claim 9 , additionally comprising a color wheel ( 6 ) for the projection of the shape deviation onto the object ( 2 ) in a false color representation.

17. An apparatus in accordance with claim 10 , additionally comprising a light source ( 4 ) and a liquid light conductor ( 5 ) for the supply of the light to the projector ( 1 ).

18. An apparatus in accordance with claim 17 , wherein the camera ( 3 ) has a camera memory for the intermediate storage of the recorded image data.

19. A method according to claim 7 , wherein the step of projecting the shape deviation onto the object ( 2 ) further comprises:

determining the 3D measurement of an object;

performing an automatic alignment and calculation of deviations from desired 3D measurements of the object;

calculating or determining a projection pattern for each 3D object point; and

calculating or determining corresponding projection pixels for each camera pixel.

20. A method in accordance with claim 7 , wherein the step of calculating or determining a projection pattern for each 3D object point is performed for each channel of an RGB color wheel.