fixing colmap installation to use apt-get since gdown on the URL unable to download colmap

[AntonioMacaronio]

in the demo colab notebook, gdown is unable to install colmap because the gdrive link is not sharable or not available.

This issue is also mentioned here:

1. https://github.com/nerfstudio-project/nerfstudio/pull/2787/files

• !conda install -c conda-forge colmap will raise a PackagesNotFoundError.

2. Colmap binary link in Colab is invalid #2406 (comment)

• the fix mentioned here will also have a PackagesNotFoundError and then the runtime always crashes/restarts

To download colmap, using apt-get solved these issues and allowed me to process my data in the following cell - it is a quick one-line and it takes about 4minutes 16seconds to install nerfstudio and its dependencies

[ginazhouhuiwu]

lgtm

[ginazhouhuiwu]

thank you!!

[brentyi]

I think that the apt version of colmap isn't GPU-accelerated, so maybe still revisiting again before #2787 is merged?

[ginazhouhuiwu]

Will definitely do!

[ginazhouhuiwu]

I think for now if it patches the issue (which it seem to do), can be merged in main. I personally didn't run into problems with conda install so I have to look into it more and see what the discrepancy is.

[brentyi]

Sounds good! I think missing GPU support in colmap is possibly also fine if it makes the install much easier. We could maybe benchmark.

[machenmusik]

I would recommend benchmarking, as my recollection of colmap non-GPU on larger datasets was... significantly slower execution.