Method for determining the relative position of a first and a second imaging device and devices therefore

1. A method comprising determining a relative position and orientation of a first and a second imaging device by comparing an image of a commonly depicted object in a first and a second image of said first and said second imaging device respectively, wherein said first and said second imaging devices are configured for providing first and second depth information respectively for said respective images and in which at least said first and said second depth information is used for said determination; and

a. determining a set of at least four reference points, said reference points recognizable on said first image and on said second image as projected reference points;

b. determining virtual reference points by deriving a virtual position of said reference points with respect to said first imaging device by using said first depth information for the image of said reference points in said first image;

c. setting a predetermined orientation of said first imaging device;

d. deriving a position of said second imaging device with respect to said virtual reference points by using said second depth information of the image of said reference points in said second image;

e. determining the orientation of said second imaging device by optimizing an alignment between the image of said reference points on said second image and the virtual reference points.

2. The method according to claim 1 , wherein said at least four reference points are determined automatically.

3. The method according to claim 1 , wherein said optimizing the alignment of the image of said reference points on said second image with the reference points comprises:

a. aligning at least one of said images of said virtual reference points in said second image with its corresponding projected reference point;

b. determining an angle of rotation around a rotation axis, defined by a line connecting the aligned projected reference point with an imaging device center, necessary in order to have an other of said images of said reference points maximally correspond to their respective virtual reference points.

4. The method according to claim 1 , further comprising taking into account intrinsic camera parameters in said determination.

5. The method according to claim 1 further comprising determining a relative position and orientation of more than two imaging devices, by iteratively determining a relative position and orientation of a further imaging device with respect to a predetermined first imaging device.

6. The method according to claim 1 , further comprising deriving 3-D information of at least one object in a scene, comprising:

providing at least two images of said scene, both images comprising said object, said images taken at different positions and orientations with respect to said object; and deriving 3-D information of said at least one object by taking into account said relative position and orientation of at least the first and second imaging device.

7. The method according to claim 6 , wherein said 3-D information of said at least one object is time dependent.

8. The method according to any of claim 6 , wherein said relative position and orientation of said at least first and second imaging devices is kept constant after initialization.

9. The method according to claim 6 , further comprising the translation of a real object into 3-D object information for use in a virtual environment.

10. A system comprising: determining a relative position and orientation of a first and a second imaging device by comparing an image of a commonly depicted object in a first and a second image of said first and said second imaging device respectively, wherein said first and said second imaging devices are configured for providing first and second depth information respectively for said respective images and in which at least said first and said second depth information is used for said determination; and said system further comprising:

a. a means for determining a set of at least four reference points, said reference points recognizable on said first image and on said second image as projected reference

b. a means for determining virtual reference points by deriving a virtual position of said reference points with respect to said first imaging device by using said first depth information for the image of said reference points in said first image;

c. a means for setting a predetermined orientation of said first imaging device;

d. a means for deriving a position of said second imaging device with respect to said virtual reference points by using said second depth information of the image of said reference points in said second image;

e. a means for determining the orientation of said second imaging device by optimizing an alignment between the image of said reference points on said second image and the virtual reference points.

11. The system according to according to claim 10 , further comprising a means for taking into account intrinsic camera parameters in said determination.

12. The system according to claim 10 further comprising a means for determining a relative position and orientation of more than two imaging devices, by iteratively determining a relative position and orientation of a further imaging device with respect to a first predetermined imaging device.

13. The method according to claim 1 , further comprising retrieving a fixed position and orientation of a predetermined number of imaging devices, the images of which are further used for 3-D video conferencing.