Problem with using COLMAP project

[Garshishka]

Using datasets from here https://github.com/pierotofy/OpenSplat/issues/1#issue-2139060707 I got no problem using OpenSplat. But when I make my own point cloud in COLMAP (using banana images from example datasets) and then run them in OpenSplat i get an error "Unsupported camera model: 2". What can cause that? I'm using COLMAP-3.9.1-windows-cuda with GUI and "automatic reconstruction" function, if that's important.

[Garshishka]

After some experiments I think I got the problem. Don't use "Automatic reconstruction". It worked with this steps:

1. Feature extraction: check "Shared for all images" and choose camera model PINHOLE. I had SIMPLE_RADIAL and it doesn't work
2. Feature matching on default parameters
3. Reconstruction
4. Export model

With this it worked!

I think this issue can be closed now

[Jonathan-Gore]

Interesting, I'm having the exact same issue as you.

I'd love someone with more knowledge give some insight on why the camera model needs to be "PINHOLE" instead of "SIMPLE_RADIAL" before this issue closes. What implications does that have for the reconstruction?

The COLMAP documentation implies that this camera model choice results in less distortion correction: https://colmap.github.io/cameras.html

Additionally, if I can better understand why the "SIMPLE_RADIAL" camera cannot be used I would be happy to contribute a Readme about a COLMAP processing guide for use with Opensplat.

[pierotofy]

It should be relatively simple to add support for simple radial. One needs to look at the definition in colmap's source code and check how the undistortion model works. Then adjust https://github.com/pierotofy/OpenSplat/blob/main/colmap.cpp#L46 accordingly.

[Jonathan-Gore]

Ok, I'm willing to take a crack at that later today!

[Jonathan-Gore]

@Garshishka Support for Simple_Radial should be live if you're building from main! Let me know how it works if you end up using it.