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Author Topic: Best way to optimise a multi-chunk model?  (Read 3517 times)

patcarbon

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Best way to optimise a multi-chunk model?
« on: October 22, 2012, 05:17:53 PM »
Hi

I've not got a 6 chunk model with a total of 1973 images.  I have about 400 low accuracy (10m) GPS camera positions (2 chunks) and about 20 high accuracy (5cm) ground control points. I've processed all the chunks (align: high, build geom: med) and I've aligned them all (point based, high).  Everything looks pretty good so far.

Now I want to optimise this model.  Since I only have 20 GCPs, there are only 2-3 per chunk.  Should I merge all the chunks before I optimise?   I have 16 gig RAM so according to the Photoscan wiki, I can re-build the geometry on medium just like I already did.

Patrice

Alexey Pankov

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Re: Best way to optimise a multi-chunk model?
« Reply #1 on: October 25, 2012, 02:53:36 PM »
In such a case I would make alignment and optimization in single chunk. Then cloned this chunk several times, set smaller bounding boxes and performed building geometry procedure in these chunks. It gives several partial models that would nicely match each other, since all of them are referenced identically.
As to optimization, it is a bit tricky. 20 GCPs may be not enough to get evenly optimized model, 10 meters accuracy of camera positions may be not enough to get accurate referencing of the whole model. Sometimes optimization by cameras and then update (affine transformation) by markers gives better results. Try both ways prior to geometry building and check which leads to a more accurate referencing.