DEM creation toolbox for SPOT 6/7 stereo imagery

This set of functions builds the physical model of SPOT 6/7 stereo imagery data and can be used to extract a DEM from such data.

This set of functions builds the physical model of SPOT 6/7 stereo imagery data and can be used to extract a DEM from such data. Further information on this model and the types of data which it is available for can be found in the SPOT 6/7 Data User Guide (https://www.intelligence-airbusds.com/en/8718-user-guides).

The processing level of the images should be primary. Furthermore, the usage of the panchromatic images is recommended.
The workflow is described in more detail in 'MasterScript.m' and readme.txt.

The design of this workflow is based on the desire to obtain only reliable altitude information from a blockmatched DEM. The division of the blockmatching algorithm into two steps ensures that areas where blockmatching is impossible are clearly identified before the neighbouring heights are taken into account. This ensures that such areas are not just "overwritten" by altitude information of neighbouring points, but are clearly marked as points where altitude information would not be reliable. The smaller the resolution of the first blockmatching algorithm (i.e. the smaller the value of the variable step is defined as in 'MasterScript.m'), the better areas where blockmatching gives faulty results are marked out. However, testing across the entire altitude range takes a lot of computation time and hence a compromise has to be taken by defining the lowest possible value of step that will result in a reasonable computation time.

(Necessary) external dependencies are:
- xml2struct.m [1]
- if UTM projections are desired, utm2deg.m [2] and deg2utm.m [3]
- if orthometric height is desired, the MATLAB Mapping Toolbox has to be added.
- Cubic_Interpolation.m [4]

Note: Pixel coordinates are defined by matrix notation, i.e. first coordinate signifies row and second signifies column.

[1] Wouter Falkena (2020). xml2struct (https://www.mathworks.com/matlabcentral/fileexchange/28518-xml2struct), MATLAB Central File Exchange. Retrieved May 26, 2020.
[2] Rafael Palacios (2020). utm2deg (https://www.mathworks.com/matlabcentral/fileexchange/10914-utm2deg), MATLAB Central File Exchange. Retrieved May 26, 2020.
[3] Rafael Palacios (2020). deg2utm (https://www.mathworks.com/matlabcentral/fileexchange/10915-deg2utm), MATLAB Central File Exchange. Retrieved May 26, 2020.
[4] Indranil Banik (2020). Cubic interpolation in 1D (https://www.mathworks.com/matlabcentral/fileexchange/61635-cubic-interpolation-in-1d), MATLAB Central File Exchange. Retrieved May 26, 2020.