What is the Theoretical Error S(X,Y,Z) of a computed 3D point?

The Theoretical Error of a computed 3D point can be seen in rayCloud when clicking on a point:


It indicates:

  • How good the relative reconstruction is in this region.
  • If the point needs to be marked on more images.

The Theoretical Error can be visualized with the Error Ellipsoid. See the following example: 

The point has been marked on only two images with a small baseline (the distance between the center of the images). As a result, there is a large Theoretical Error in the direction of the rays:


When the point is marked on a new image, the Theoretical Error gets smaller:


For more information on how to visualize the Theoretical Error with an Ellipsoid in the rayCloud: Menu View > rayCloud > Left sidebar > Layers > Tie Points .

In the following example, the point is marked on only 4 images with a small baseline and on one of them (2) it is marked erroneously:


When the point is correctly marked on more images, the following result is obtained:


For more information on how the error of an estimated 3D point is computed and defined: 3D error estimation from tie points.

  • The error in Z is larger than the error in X and Y for nadir aerial images.
  • If the error is larger than three times the GSD, the estimation of the 3D point needs to be improved by manually refining the point on the images using the rayCloud Editor.


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