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3D points inverted?

I have been processing the data online through mapsmadeeasy as well as on my desktop on a software called Agisoft...both of them seem to have the same issue when it comes to generating the 3D model when I try to fly over complex areas like forested areas. The strange thing I am noticing is that the vertical information is there, but it appears to be recorded as negative values? I ran an ultra coverage (90% overlap) through Agisoft and had the same problem. I haven't run an ultra online as it has a little over 200 pictures but plan to run a subset side by side shortly. Any idea why the negative values and is there a fix to this?

Alex Bilyk

Official comment


It isn't that the points are inverted or actually negative. It is hard to triangulate locations from multiple images when things are moving. Sometimes the solution comes out to be in an unexpected location (ie below the ground) if something isn't in the same place in two different images.

Using images to reconstruct a 3D scene has to Achilles heels: trees and water. Water is almost never still and if it is, it has a lot of glare issues. Trees are going to be moving in any amount of wind.

If more overlap doesn't do it, flying higher will fix the issue with trees and can help a bit with water. Or only map treed areas on the stillest of days.

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