Info on accuracy/resolution provided by Agisoft photoscan.

[subham23jain]

Hi,

I am a Ph.D. student at IIT Kanpur (India).

A person in my lab has been using Autodesk ReMake to estimate surface area of objects (by reconstructing the 3D object using structure from motion at ambient lighting condition using an SLR camera).

After scaling the object, he has found the surface area in millimeter (mm) square. ReMake  gives us an opportunity to express the dimension of the object in micro meter and millimeter.

I am skeptical that millimeter (and micro meter) accuracy of the dimension of 3D object reconstructed can be achieved by applications that use photogrammetry or structure from motion (like Agisoft does). So my question is :

1. What is the order of the 'noise' in get the dense point cloud in Agisoft if we want to measure the XYZ coordinates of the 3D reconstructed object in millimeter (from some specified reference)?

2. So what is the maximum resolution can we achieve by Agisoft ? Can we measure dimension in mm, with a noise ratio of say, less than 5%? With what maximum resolution can I measure coordinates of objects using Agisoft ?

I am sure I have not provided all the information that you need to answer my question. Please reply back to seek clarification.


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Yours sincerely,
Subham Jain

P.S. I am new to the area of computer vision and photogrammetry. I have a background in Civil Engineering. So forgive me if I have stated any incorrect information.

[Photogrammetryfacts]

Can't you measure this your self? If you make a model from something with a known shape you can calculate the difference between the ground truth and the model to find the accuracy?

[Alexey Pasumansky]

Hello Subham,

I think that the answers to your question would depend on the quality of the input images (sharpness of details, noise level, focal depth) and their effective resolution. For example, if taking photos from the 300m altitude with common 25mm lens you wouldn't be likely able to get sub-cm accuracy, but if you are taking the photos for close-range project, then mm accuracy is achievable.

But also the texture of the scanned surface/object is important for accurate reconstruction.