Pytorch3d: meshes.extend causes problem with tensor.view

[michele-arrival]

simple code where an object of class "Meshes" is extended from 1 to a batch size > 1 via meshes.extend(N) causes:

  File "/[...]/env/lib/python3.6/site-packages/pytorch3d/structures/utils.py", line 194, in padded_to_packed
    x_packed = x.view(-1, D)  # flatten padded
RuntimeError: view size is not compatible with input tensor's size and stride (at least one dimension spans across two contiguous subspaces). Use .reshape(...) instead.

code to replicate:

import torch
from pytorch3d.renderer import OpenGLPerspectiveCameras, BlendParams, \
    RasterizationSettings, MeshRasterizer, MeshRenderer, TexturedSoftPhongShader, DirectionalLights
import numpy as np
from pytorch3d.io import load_objs_as_meshes

device = torch.device("cuda:0")

meshes = load_objs_as_meshes(["./models/cow_mesh/cow.obj"]).to(device)
meshes = meshes.extend(2)


cameras = OpenGLPerspectiveCameras(device=device)

blend_params = BlendParams(sigma=1e-4, gamma=1e-4, background_color=(0., 0., 0.))

raster_settings = RasterizationSettings(
    blur_radius=np.log(1. / 1e-4 - 1.) * blend_params.sigma,
    faces_per_pixel=100
)

lights = DirectionalLights(device=device)

renderer = MeshRenderer(
    rasterizer=MeshRasterizer(
        cameras=cameras, raster_settings=raster_settings
    ),
    shader=TexturedSoftPhongShader(blend_params=blend_params, lights=lights)
)

images = renderer(meshes_world=meshes)

in other versions of my own code i get the error somewhere else, e.g.:

./renderer/mesh/texturing.py", line 56, in interpolate_texture_map
    pixel_uvs = pixel_uvs.permute(0, 3, 1, 2, 4).view(N * K, H_out, W_out, 2)

[gkioxari]

This is likely due to the noncontiguity of the tensor. Try reshape instead as suggested by the RuntimeError message.

[michele-arrival]

I can certainly change it in my version. However doesn't it sound like a bug that will occur often for many users?

[gkioxari]

Absolutely! This was just intended to unblock you!

[gkioxari]

I fixed the issues you report above with https://github.com/facebookresearch/pytorch3d/commit/6c48ff6ad9005cfc03704c77531a4a25d1c8d843. If you find similar issues please report them or even add a PR that fixes them if you prefer! Thank you again for reporting this :)

[michele-arrival]

Absolutely! This was just intended to unblock you!

many thanks for the fix!