Support 2dgs with the latest viewer

[RongLiu-Leo]

Recording.2025-05-25.172251.mp4

• This PR adds support for running 2DGS with the latest version of nerfview, ensuring compatibility and functionality. Without this update, 2DGS cannot be executed properly. Render mode supports rgb, depth, normal, and alpha.

• Replaced the use of colormap with apply_float_colormap. While both provide similar logic, colormap triggers runtime errors in my environment. Suggest to unify the function usage and stick to apply_float_colormap.

[AlexMorgand]

Nice!

I did something similar in #540 adding a backend option if you guys want to keep the simple_viewer as one file. The branch is a bit old but just a reference for further discussion

[liruilong940607]

This looks cool! But the depth rendering is pretty weird -- doesn't look like depth map at all. Is the viewer accessing the correct depth data?

[RongLiu-Leo]

Let me double check.

[RongLiu-Leo]

Recording.2025-05-27.194934.mp4

Looks good now! Thanks for pointing it out.

[liruilong940607]

Nice. Thanks for fixing 2DGS viewer (and trainer)!

[Chuan-10]

Hi, thank you for the great work on gsplat!

I noticed a small bug in examples/simple_trainer_2dgs.py, which seems to be related to the recent Arbitrary batching feature. The current implementation of the depth and normal rendering logic may cause bugs in some cases.

It could be modified as follows:

if render_tab_state.render_mode == "depth":
    # normalize depth to [0, 1]
    depth = render_median[0]
    if render_tab_state.normalize_nearfar:
        near_plane = render_tab_state.near_plane
        far_plane = render_tab_state.far_plane
    else:
        near_plane = depth.min()
        far_plane = depth.max()
    depth_norm = (depth - near_plane) / (far_plane - near_plane + 1e-10)
    depth_norm = torch.clip(depth_norm, 0, 1)
    if render_tab_state.inverse:
        depth_norm = 1 - depth_norm
    renders = apply_float_colormap(depth_norm, render_tab_state.colormap).cpu().numpy()
elif render_tab_state.render_mode == "normal":
    render_normals = render_normals[0] * 0.5 + 0.5  # normalize to [0, 1]
    renders = render_normals.cpu().numpy()
elif render_tab_state.render_mode == "alpha":
    alpha = render_alphas[0, ..., 0:1]
    renders = apply_float_colormap(alpha, render_tab_state.colormap).cpu().numpy()

This small change fixes the depth and normal rendering bugs.

Thanks again for the excellent repo!