Make USD and OBJ importers consistent for all properties, change hand…

…ling of material assignments, fix bugs, add option to triangulate. (#724)

Non-backward compatible changes to OBJ importer, including:
  - renamed vertex_normals to normals and fixed doc
  (this value is normals array is not num_verts x 3, but num_normals x 3)
  - renamed face_normals to face_normals_idx, which is more accurate
  - changed material_order to material_assignments tensor with material_id per face
  - materials are now returned in alphabetical order
  - fixed handling of materials for non-homogeneous meshes
  - fixed skip handling of non-homogeneous meshes

Other changes to OBJ importer:
  - added option to triangulate
  - added handler to fill in missing materials
  - added material_name to materials

Non-backward compatible changes to USD importer, including:
  - changes material_order to material_assignments tensor with material_id per face
  (this is original USD repersentation)
  - materials are now returned in alphabetical order
  - removed deprecated handlers in kaolin.io.usd

Other changes to USD importer:
  - major refactoring of the USD importer code; multiple bug fixes; more robust tests
  - added material_name to materials
  - added option to triangulate
  - fixed a bug in USD importer handling of uvs in non-homogeneous meshes

Other changes:
  - deprecated heterogeneous_mesh_handler_naive_homogenize, renaming it mesh_handler_naive_triangulate
  (as it is not specific to heterogeneous mesh handling)
  - material assignments are now properly handled during triangulation
  - modified and simplified notebooks, given changes to API
  - added multi-object multi-material test file: amsterdam.obj, amsterdam.usd
  - modified notebooks and recipes to be more robust to missing data (e.g. shapenet)
  and to run both locally and on CI
  - added IO consistency checks for OBJ/USD for the new amsterdam mesh
  - removed heterogeneous_mesh_handler_empty, as we will no longer be able to support it with Mesh API

Signed-off-by: Maria Masha Shugrina <mshugrina@nvidia.com>
Co-authored-by: Maria Masha Shugrina <mshugrina@nvidia.com>

docs/modules/kaolin.io.obj.rst

@@ -18,6 +18,7 @@ Functions
         ignore_error_handler,
         skip_error_handler,
         default_error_handler,
+        create_missing_materials_error_handler,
         MaterialError,
         MaterialLoadError,
         MaterialFileError,
@@ -29,3 +30,4 @@ Error Handler
 .. autofunction:: ignore_error_handler
 .. autofunction:: skip_error_handler
 .. autofunction:: default_error_handler
+.. autofunction:: create_missing_materials_error_handler

docs/modules/kaolin.io.usd.rst

@@ -21,8 +21,8 @@ More tutorials and documentation can be found `here <https://graphics.pixar.com/
 Viewing USD Files
 ~~~~~~~~~~~~~~~~~
 USD files can be visualized with realtime pathtracing using the [Omniverse Kaolin App](https://docs.omniverse.nvidia.com/app_kaolin/app_kaolin/user_manual.html#training-visualizer).
-Alternatively, you may use Pixar's USDView which can be obtained by visiting 
-`https://developer.nvidia.com/usd <https://developer.nvidia.com/usd>`_ and selecting the 
+Alternatively, you may use Pixar's USDView which can be obtained by visiting
+`https://developer.nvidia.com/usd <https://developer.nvidia.com/usd>`_ and selecting the
 corresponding platform under *.USD Pre-Built Libraries and Tools*.
 
 
@@ -35,20 +35,4 @@ Functions
 .. automodule:: kaolin.io.usd
     :members:
     :exclude-members:
-        mesh_return_type,
-        heterogeneous_mesh_handler_empty, 
-        heterogeneous_mesh_handler_naive_homogenize, 
-        heterogeneous_mesh_handler_skip,
-        NonHomogeneousMeshError
-
-Heterogeneous Mesh Handlers
----------------------------
-
-.. autofunction:: heterogeneous_mesh_handler_empty
-.. autofunction:: heterogeneous_mesh_handler_naive_homogenize
-.. autofunction:: heterogeneous_mesh_handler_skip
-
-Exceptions
-----------
-
-.. autoclass:: NonHomogeneousMeshError
+        mesh_return_type

examples/recipes/preprocess/fast_mesh_sampling.py

@@ -14,13 +14,13 @@
 # ==============================================================================================================
 
 import argparse
-import sys
+import os
 import torch
 
 import kaolin as kal
 
 parser = argparse.ArgumentParser(description='')
-parser.add_argument('--shapenet-dir', type=str,
+parser.add_argument('--shapenet-dir', type=str, default=os.getenv('KAOLIN_TEST_SHAPENETV2_PATH'),
                     help='Path to shapenet (v2)')
 parser.add_argument('--cache-dir', type=str, default='/tmp/dir',
                     help='Path where output of the dataset is cached')
@@ -52,22 +52,11 @@ def preprocessing_transform(inputs):
     uvs = torch.nn.functional.pad(mesh.uvs.unsqueeze(0) % 1, (0, 0, 0, 1)) * 2. - 1.
     uvs[:, :, 1] = -uvs[:, :, 1]
     face_uvs_idx = mesh.face_uvs_idx
-    materials_order = mesh.materials_order
+    face_material_idx = mesh.material_assignments
     materials = [m['map_Kd'].permute(2, 0, 1).unsqueeze(0).float() / 255. if 'map_Kd' in m else
                  m['Kd'].reshape(1, 3, 1, 1)
                  for m in mesh.materials]
-
-    nb_faces = faces.shape[0]
-    num_consecutive_materials = \
-        torch.cat([
-            materials_order[1:, 1],
-            torch.LongTensor([nb_faces])
-        ], dim=0)- materials_order[:, 1]
-
-    face_material_idx = kal.ops.batch.tile_to_packed(
-        materials_order[:, 0],
-        num_consecutive_materials
-    ).squeeze(-1)
+
     mask = face_uvs_idx == -1
     face_uvs_idx[mask] = 0
     face_uvs = kal.ops.mesh.index_vertices_by_faces(

examples/recipes/preprocess/occupancy_sampling.py

@@ -7,10 +7,12 @@
 #    https://kaolin.readthedocs.io/en/latest/modules/kaolin.ops.mesh.html#triangular-meshes
 # ==============================================================================================================
 
+import os
 import torch
 import kaolin
 
-mesh_path = "../../samples/sphere.obj"  # Path to some .obj file with textures
+FILE_DIR = os.path.abspath(os.path.dirname(os.path.abspath(__file__)))
+mesh_path = os.path.join(FILE_DIR, os.pardir, os.pardir, "samples", "sphere.obj")   # Path to some .obj file with textures
 num_samples = 100000                    # Number of sample points
 
 # 1. Load a watertight mesh from obj file