Camera Parameters in the output XMP file

Development Asset Creation Photogrammetry
, ,
1

A questions on Metadata (XMP) files in Reality Capture Help Documentation.

Do xcr:Rotation and xcr:Position values in the sample XMP file correspond to the origin of the World Coordinate System (P_w) in Reality Capture?

If not, what do these parameters refer to?

2

Hi Jesse,
those parameters refer to RealityCapture’s XMP coordinate system (https://dev.epicgames.com/community/learning/knowledge-base/mozL/capturing-reality-differences-between-exported-coordinate-systems-in-realitycapture#:~:text=and%20Y%20axis.-,Same%20as%20XMP%20coordinate%20system,-The%20XMP%20coordinate).

1 Like
3

Hi Ondrej, thanks for your quick response.

  1. If the parameters refer to the XMP coordinate system, does that mean:
  • for specifying the origin of the XMP coordinate system, we set a ground control point at (0, 0, 0)
  • then re-align images
    Finally, the images’ rotations and positions turn to refer to the ground control point (0, 0, 0) we have created

?

  1. Is it correct to use XMP Coordinate System as the World Coordinate System of the final alignment?

  2. If the above is not the case, where to find the origin of the XMP coordinate system. Because I want to convert the position of a specific point in Camera Coordinate System into World Coordinate System
    (Suppose we already got the position in Camera Coordinate System by converting the 2D position in image using Camera Intrinsics).

Thanks always for your kind support.

4

As I sent you, XMP system refers to the system after first alignment. The centre of the system is in the grid centre you can see in 3D view.
For such transformation this could be helpful:https://dev.epicgames.com/community/learning/knowledge-base/vzwB/capturing-reality-realitycapture-xmp-camera-math