Importing obj files without usemtl

Summary:
When there is no "usemtl" statement in the .obj file use material from .mtl if there is one.
https://github.com/facebookresearch/pytorch3d/issues/1068

Reviewed By: bottler

Differential Revision: D34141152

fbshipit-source-id: 7a5b5cc3f0bb287dc617f68de2cd085db8f7ad94
This commit is contained in:
Sergei Ovchinnikov 2022-02-10 09:38:17 -08:00 committed by Facebook GitHub Bot
parent 12f20d799e
commit ef21a6f6aa
7 changed files with 12062 additions and 4 deletions

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@ -454,8 +454,18 @@ def _load_texture_images(
final_material_properties = {}
texture_images = {}
used_material_names = list(material_names)
if not used_material_names and material_properties:
if len(material_properties) > 1:
raise ValueError(
"Multiple materials but no usemtl declarations in the obj file"
)
# No materials were specified in obj file and only one is in the
# specified .mtl file, so we use it.
used_material_names.append(next(iter(material_properties.keys())))
# Only keep the materials referenced in the obj.
for material_name in material_names:
for material_name in used_material_names:
if material_name in texture_files:
# Load the texture image.
path = os.path.join(data_dir, texture_files[material_name])

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@ -526,9 +526,8 @@ def _load_materials(
if not load_textures:
return None, None
if not material_names or f is None:
if material_names:
warnings.warn("No mtl file provided")
if f is None:
warnings.warn("No mtl file provided")
return None, None
if not path_manager.exists(f):
@ -620,6 +619,13 @@ def _load_obj(
device=device,
)
if material_colors and not material_names:
# usemtl was not present but single material was present in the .mtl file
material_names.append(next(iter(material_colors.keys())))
# replace all -1 by 0 material idx
if torch.is_tensor(faces_materials_idx):
faces_materials_idx.clamp_(min=0)
if create_texture_atlas:
# Using the images and properties from the
# material file make a per face texture map.

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@ -0,0 +1,7 @@
# Acknowledgements
This is copied version of docs/tutorials/data/cow_mesh with removed line 6159 (usemtl material_1) to test behavior without usemtl material_1 declaration.
Thank you to Keenen Crane for allowing the cow mesh model to be used freely in the public domain.
###### Source: http://www.cs.cmu.edu/~kmcrane/Projects/ModelRepository/

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@ -0,0 +1,9 @@
newmtl material_1
map_Kd cow_texture.png
# Test colors
Ka 1.000 1.000 1.000 # white
Kd 1.000 1.000 1.000 # white
Ks 0.000 0.000 0.000 # black
Ns 10.0

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tests/data/missing_usemtl/cow.obj Executable file

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@ -658,6 +658,18 @@ class TestMeshObjIO(TestCaseMixin, unittest.TestCase):
self.assertTrue(aux.material_colors is None)
self.assertTrue(aux.texture_images is None)
def test_load_no_usemtl(self):
obj_filename = "missing_usemtl/cow.obj"
# obj_filename has no "usemtl material_1" line
filename = os.path.join(DATA_DIR, obj_filename)
# TexturesUV type
mesh = IO().load_mesh(filename)
self.assertIsNotNone(mesh.textures)
verts, faces, aux = load_obj(filename)
self.assertTrue("material_1" in aux.material_colors)
self.assertTrue("material_1" in aux.texture_images)
def test_load_mtl_fail(self):
# Faces have a material
obj_file = "\n".join(