Topics

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General / Dense cloud at lower resolutions

« on: February 18, 2016, 07:34:13 PM »

How does PS calculate the dense cloud at lower resolutions than Ultra High? For example, at High does the program look at every second pixel (or fourth pixel for Medium etc) or does it reduce the resolution of the photographs by successive factors of 2 and use averaged values for every pixel in the reduced images?And would this make a difference to the accuracy of resulting DEMs?

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General / Resampling method for orthophotos

« on: February 04, 2016, 03:13:10 PM »

A client has asked what resampling method is used when generating orthophotos. The previous software I used for orthorectification (Geomatica) gave several choices - nearest neighbour, bilinear interpolation (weighted average of four closest pixels), cubic convolution (weighted average of 16 closest pixels) and a host of other more esoteric filters. I generally used cubic convolution as giving the best-looking result. What does PS use? There are hints that for some purposes it uses nearest neighbour, but I can't find any information specifically about generating orthophotos.