Inverting Model

[jl]

Hi,

I have a referenced model for which I would like to invert the Z value and export a referenced DEM in a UTM coordinate system.  The purpose is to get the height of the ground beneath overhangs like bridges.  I have tried to change the chunk's coordinate transform by doing:

Code: [Select]

chunk.transform.matrix = PhotoScan.Matrix.diag([1,1,1,-1]) * chunk.transform.matrix
This correctly flips the Z axis in the UI, but it also changes xy coordinates, and when I export the DEM the result is not correct/useful.  Using [-1,-1,-1,-1] keeps the georeferenced coordinates in the same general area, but the image is flipped and not usefully aligned.  What is the correct way to do this?  I don't think setting the projection in chunk.exportDem is useful because I need the output to still be georeferenced.

Thanks,
John

[Alexey Pasumansky]

Hello John,


It is not possible to invert only Z, as X and Y axis directions should be rotated accordingly to keep the same relative orientation.

Wouldn't it be more simple to load regular DEM to Quantum-GIS and perform the difference calculation between some elevation level and this DEM?