Negative densities

[jason5306]

Hi Ruyi,
I wonder if r2 gaussian output negative densities, for example the to-be-reconstructed volume has negative intensities. In such case, does that mean I need to normalize the volume to [0,1]?

Thank you!

[Ruyi-Zha]

Hi, to support negative intensities, you may need to edit certain lines in the CUDA forward and backward functions. For instance, you could start by commenting out this line and similar ones in other functions.

r2_gaussian/r2_gaussian/submodules/xray-gaussian-rasterization-voxelization/cuda_rasterizer/forward.cu

Line 374 in 788971d

if (alpha < 0.00001f)

Additionally, consider modifying the density_activation function, as it currently uses softplus—which only outputs values in the range of [0,+inf].

r2_gaussian/r2_gaussian/gaussian/gaussian_model.py

Line 61 in 788971d

self.density_activation = torch.nn.Softplus() # use softplus for [0, +inf]

[jason5306]

Thanks a lot, I'll try if it work. Thank you!