ambient lighting

Summary:
Specific object to represent light which is 100% everywhere. Sometimes lighting is irrelevant, for example when viewing a mesh which has lighting already baked in.

This is not primarily aiming for a performance win but I think the test which has changed might be a bit faster.

Reviewed By: theschnitz

Differential Revision: D26405151

fbshipit-source-id: 82eae55de0bee918548a3eaf031b002cb95e726c

Author: bottler

pytorch3d/renderer/__init__.py

@@ -34,7 +34,7 @@
     ray_bundle_to_ray_points,
     ray_bundle_variables_to_ray_points,
 )
-from .lighting import DirectionalLights, PointLights, diffuse, specular
+from .lighting import AmbientLights, DirectionalLights, PointLights, diffuse, specular
 from .materials import Materials
 from .mesh import (
     HardFlatShader,

pytorch3d/renderer/lighting.py

@@ -158,7 +158,7 @@ def __init__(
         diffuse_color=((0.3, 0.3, 0.3),),
         specular_color=((0.2, 0.2, 0.2),),
         direction=((0, 1, 0),),
-        device: str = "cpu",
+        device="cpu",
     ):
         """
         Args:
@@ -219,7 +219,7 @@ def __init__(
         diffuse_color=((0.3, 0.3, 0.3),),
         specular_color=((0.2, 0.2, 0.2),),
         location=((0, 1, 0),),
-        device: str = "cpu",
+        device="cpu",
     ):
         """
         Args:
@@ -268,6 +268,42 @@ def specular(self, normals, points, camera_position, shininess) -> torch.Tensor:
         )
 
 
+class AmbientLights(TensorProperties):
+    """
+    A light object representing the same color of light everywhere.
+    By default, this is white, which effectively means lighting is
+    not used in rendering.
+    """
+
+    def __init__(self, *, ambient_color=None, device="cpu"):
+        """
+        If ambient_color is provided, it should be a sequence of
+        triples of floats.
+
+        Args:
+            ambient_color: RGB color
+            device: torch.device on which the tensors should be located
+
+        The ambient_color if provided, should be
+            - 3 element tuple/list or list of lists
+            - torch tensor of shape (1, 3)
+            - torch tensor of shape (N, 3)
+        """
+        if ambient_color is None:
+            ambient_color = ((1.0, 1.0, 1.0),)
+        super().__init__(ambient_color=ambient_color, device=device)
+
+    def clone(self):
+        other = self.__class__(device=self.device)
+        return super().clone(other)
+
+    def diffuse(self, normals, points) -> torch.Tensor:
+        return torch.zeros_like(points)
+
+    def specular(self, normals, points, camera_position, shininess) -> torch.Tensor:
+        return torch.zeros_like(points)
+
+
 def _validate_light_properties(obj):
     props = ("ambient_color", "diffuse_color", "specular_color")
     for n in props:

tests/test_render_meshes.py

@@ -24,7 +24,7 @@
     PerspectiveCameras,
     look_at_view_transform,
 )
-from pytorch3d.renderer.lighting import PointLights
+from pytorch3d.renderer.lighting import AmbientLights, PointLights
 from pytorch3d.renderer.materials import Materials
 from pytorch3d.renderer.mesh import TexturesAtlas, TexturesUV, TexturesVertex
 from pytorch3d.renderer.mesh.rasterizer import MeshRasterizer, RasterizationSettings
@@ -626,12 +626,7 @@ def test_join_uvs(self):
             image_size=256, blur_radius=0.0, faces_per_pixel=1
         )
 
-        lights = PointLights(
-            device=device,
-            ambient_color=((1.0, 1.0, 1.0),),
-            diffuse_color=((0.0, 0.0, 0.0),),
-            specular_color=((0.0, 0.0, 0.0),),
-        )
+        lights = AmbientLights(device=device)
         blend_params = BlendParams(
             sigma=1e-1,
             gamma=1e-4,
@@ -780,12 +775,7 @@ def test_join_verts(self):
             image_size=256, blur_radius=0.0, faces_per_pixel=1
         )
 
-        lights = PointLights(
-            device=device,
-            ambient_color=((1.0, 1.0, 1.0),),
-            diffuse_color=((0.0, 0.0, 0.0),),
-            specular_color=((0.0, 0.0, 0.0),),
-        )
+        lights = AmbientLights(device=device)
         blend_params = BlendParams(
             sigma=1e-1,
             gamma=1e-4,
@@ -863,12 +853,7 @@ def test_join_atlas(self):
             perspective_correct=False,
         )
 
-        lights = PointLights(
-            device=device,
-            ambient_color=((1.0, 1.0, 1.0),),
-            diffuse_color=((0.0, 0.0, 0.0),),
-            specular_color=((0.0, 0.0, 0.0),),
-        )
+        lights = AmbientLights(device=device)
         blend_params = BlendParams(
             sigma=1e-1,
             gamma=1e-4,