ambient lights batching #1043

Summary:
convert_to_tensors_and_broadcast had a special case for a single input, which is not used anywhere except fails to do the right thing if a TensorProperties has only one kwarg. At the moment AmbientLights may be the only way to hit the problem. Fix by removing the special case.

Fixes https://github.com/facebookresearch/pytorch3d/issues/1043

Reviewed By: nikhilaravi

Differential Revision: D33638345

fbshipit-source-id: 7a6695f44242e650504320f73b6da74254d49ac7

pytorch3d/renderer/utils.py

@@ -349,7 +349,4 @@ def convert_to_tensors_and_broadcast(
         expand_sizes = (N,) + (-1,) * len(c.shape[1:])
         args_Nd.append(c.expand(*expand_sizes))
 
-    if len(args) == 1:
-        args_Nd = args_Nd[0]  # Return the first element
-
     return args_Nd

tests/test_lighting.py

@@ -9,7 +9,7 @@ import unittest
 import numpy as np
 import torch
 from common_testing import TestCaseMixin
-from pytorch3d.renderer.lighting import DirectionalLights, PointLights
+from pytorch3d.renderer.lighting import AmbientLights, DirectionalLights, PointLights
 from pytorch3d.transforms import RotateAxisAngle
 
 
@@ -121,6 +121,17 @@ class TestLights(TestCaseMixin, unittest.TestCase):
         with self.assertRaises(ValueError):
             PointLights(location=torch.randn(10, 4))
 
+    def test_initialize_ambient(self):
+        N = 13
+        color = 0.8 * torch.ones((N, 3))
+        lights = AmbientLights(ambient_color=color)
+        self.assertEqual(len(lights), N)
+        self.assertClose(lights.ambient_color, color)
+
+        lights = AmbientLights(ambient_color=color[:1])
+        self.assertEqual(len(lights), 1)
+        self.assertClose(lights.ambient_color, color[:1])
+
 
 class TestDiffuseLighting(TestCaseMixin, unittest.TestCase):
     def test_diffuse_directional_lights(self):