# Object 3D world coordinates from multiple images

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sksk on 25 Oct 2022
Edited: sksk on 25 Oct 2022
I Want to find Object 3D world coordinates (called Photogrammetry) using coded targets
Using single camera, multiple images
Known
• Object 2D image coordinates (x,y) == coded targets
• Camera intrinsics, extrinsics parameters (using Calibration Checkerboard)
• Camera world pose from each images ( Image 1 : R,t / Image 2 : R,t ••• ) - Extracted R,tvec by camera calibration method
Unknown : Object 3D coordinates (x,y,z) From real scale
this func and get worldpoints from two images (Using a known distance of length like Ruler)
and the precision was not bad either.
Multiple images, I know TriangulateMultiview and bundleAdjustment
But this func impossible to calculate 3D-coordinates considering the real 'Scale'
1. How do I get 3D - coordinates that are scaled from multiple images?
2. Sfm 3d reconstruction can solve this questions?

Qu Cao on 25 Oct 2022
You will need a stereo camera to give you the actual dimension of 3-D objects.
Alternatively,if you know the size of an object in the triangulated 3-D points, you can estimate the scale. See this section of the Structure From Motion From Two Views example.
sksk on 25 Oct 2022
Edited: sksk on 25 Oct 2022
You will need a stereo camera to give you the actual dimension of 3-D objects.
• you mean, single camera using stereo visions and stereo cameras are different?
Alternatively,if you know the size of an object in the triangulated 3-D points, you can estimate the scale.
• yes i did it with known the size of an object (Like Ruler)
See this section of the Structure From Motion From Two Views example.
• it takes only two views examples and i saw Structure from motion multiple Views on Matlab but i think it can't estimate real scale of object,,, cuz i need both accuracy and precision 3d-coordinates

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