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Author Topic: Drawed lines or polygons deform on other photos  (Read 581 times)

mehran.daemian

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Drawed lines or polygons deform on other photos
« on: October 01, 2021, 12:27:04 PM »
Hello , after aligning photos when you draw a line on a photo you can see that it deforms on other photos and is not on its true place as attached files! what's the problem exactly?

JMR

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Re: Drawed lines or polygons deform on other photos
« Reply #1 on: October 04, 2021, 12:23:18 AM »
This is normal, when you draw on a photo, your vertices will take 3D position from available underlying 3D source: mesh, DEM, dense cloud... so you click on a given pixel (2D) but you are creating a point in the model scene(3D). When this 3D point is back-projected to other photos, it can be misplaced because the 3D source can be defective at this point or some obstacle is intersected at different position along the projective ray.
To solve it, you need to attach markers to vertices. Attached markers behave very much like regular markers, so when you pin a marker in two or more photos, you are determining the 3D location by multiple ray intersection rather than by intersection of a 3D object.
If your photos are well oriented, then the reprojections will appear in the right places in all of them.

I hope it helped.

José Martínez
GEOBIT & ACCUPIXEL
Metashape training.

mehran.daemian

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Re: Drawed lines or polygons deform on other photos
« Reply #2 on: November 12, 2021, 10:07:50 AM »
Thanks for your attention , but something is not clear for me. You mean instead of creating vertices, I must create markers in vertices? I have some markers as GCPs, isn't it enough?