Automatic 3D computations

To compute 3D object coordinates from the measured 2D coordinates, the following procedure is performed:

• An average height is estimated from all pixels inside the object using the DSM if it exists. If there is no DSM, the height is set to the last measured height as an initial approximation.

• For an interval of +/- 10 metres from the approximate height, the following is done:

• Using the current height, the pixel coordinates of the break points are transformed to object space (X, Y, Z) coordinates.

• The object space coordinates are projected to image coordinates of the second image.

• Each break point is matched and a score is computed for all the matches at the current height. If an image is multispectral, the bands are locally converted to a panchromatic image before matching.

• If the score is higher than any previous height, the current height is saved as the best.

• Continue with next height.

You can control the automatic computations by adjusting parameters in the settings dialog.