Boese0601 / RC-MVSNet

Hi~ Thanks for your open code!
I have read your paper and code, and one key step is to do ray marching in implicit neural volume for volume rendering, where the sampling points on the ray are converted to ndc space; It is well known that in Nerf, the ray marching is completed in the world coordinate system. Because it's converted to the world coordinate system by the camera pose.
I am confused about why can the ray marching of the implicit neural volume be done in the ndc space. Is the implicit neural volume in the ndc space after regularization? What's the physical meaning behind it? Since I can't seem to find the code to convert the final result from the ndc coordinate system to the world coordinate system, can you help me point it out？
BTW, If the implicit neural volume is indexed in NDC space, shouldn't it be trilinear interpolation? Why bilinear interpolation? Or is this a representation of pytorch ：）

RC-MVSNet/models/render_utils.py

Line 329 in c8dfe7c

    
           features = F.grid_sample(volume_feature, grid, align_corners=True, mode='bilinear')[:,:,0].permute(2,3,0,1).squeeze()#, padding_mode="border"

Looking forward to your reply!

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