Lighting broadcasting bug fix

Summary: Fixed multiple issues with shape broadcasting in lighting, shading and blending and updated the tests.

Reviewed By: bottler

Differential Revision: D28997941

fbshipit-source-id: d3ef93f979344076b1d9098a86178b4da63844c8

Author: nikhilaravi

pytorch3d/renderer/blending.py

@@ -1,12 +1,11 @@
 # Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
 
 
-from typing import NamedTuple, Sequence
+from typing import NamedTuple, Sequence, Union
 
 import torch
 from pytorch3d import _C  # pyre-fixme[21]: Could not find name `_C` in `pytorch3d`.
 
-
 # Example functions for blending the top K colors per pixel using the outputs
 # from rasterization.
 # NOTE: All blending function should return an RGBA image per batch element
@@ -117,7 +116,11 @@ def sigmoid_alpha_blend(colors, fragments, blend_params) -> torch.Tensor:
 
 
 def softmax_rgb_blend(
-    colors, fragments, blend_params, znear: float = 1.0, zfar: float = 100
+    colors,
+    fragments,
+    blend_params,
+    znear: Union[float, torch.Tensor] = 1.0,
+    zfar: Union[float, torch.Tensor] = 100,
 ) -> torch.Tensor:
     """
     RGB and alpha channel blending to return an RGBA image based on the method
@@ -184,11 +187,16 @@ def softmax_rgb_blend(
     # overflow. zbuf shape (N, H, W, K), find max over K.
     # TODO: there may still be some instability in the exponent calculation.
 
+    # Reshape to be compatible with (N, H, W, K) values in fragments
+    if torch.is_tensor(zfar):
+        # pyre-fixme[16]
+        zfar = zfar[:, None, None, None]
+    if torch.is_tensor(znear):
+        znear = znear[:, None, None, None]
+
     z_inv = (zfar - fragments.zbuf) / (zfar - znear) * mask
     # pyre-fixme[16]: `Tuple` has no attribute `values`.
-    # pyre-fixme[6]: Expected `Tensor` for 1st param but got `float`.
     z_inv_max = torch.max(z_inv, dim=-1).values[..., None].clamp(min=eps)
-    # pyre-fixme[6]: Expected `Tensor` for 1st param but got `float`.
     weights_num = prob_map * torch.exp((z_inv - z_inv_max) / blend_params.gamma)
 
     # Also apply exp normalize trick for the background color weight.

pytorch3d/renderer/lighting.py

@@ -253,12 +253,26 @@ def clone(self):
         other = self.__class__(device=self.device)
         return super().clone(other)
 
+    def reshape_location(self, points) -> torch.Tensor:
+        """
+        Reshape the location tensor to have dimensions
+        compatible with the points which can either be of
+        shape (P, 3) or (N, H, W, K, 3).
+        """
+        if self.location.ndim == points.ndim:
+            # pyre-fixme[7]
+            return self.location
+        # pyre-fixme[29]
+        return self.location[:, None, None, None, :]
+
     def diffuse(self, normals, points) -> torch.Tensor:
-        direction = self.location - points
+        location = self.reshape_location(points)
+        direction = location - points
         return diffuse(normals=normals, color=self.diffuse_color, direction=direction)
 
     def specular(self, normals, points, camera_position, shininess) -> torch.Tensor:
-        direction = self.location - points
+        location = self.reshape_location(points)
+        direction = location - points
         return specular(
             points=points,
             normals=normals,

pytorch3d/renderer/mesh/shading.py

@@ -14,8 +14,8 @@ def _apply_lighting(
 ) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
     """
     Args:
-        points: torch tensor of shape (N, P, 3) or (P, 3).
-        normals: torch tensor of shape (N, P, 3) or (P, 3)
+        points: torch tensor of shape (N, ..., 3) or (P, 3).
+        normals: torch tensor of shape (N, ..., 3) or (P, 3)
         lights: instance of the Lights class.
         cameras: instance of the Cameras class.
         materials: instance of the Materials class.
@@ -35,13 +35,19 @@ def _apply_lighting(
     ambient_color = materials.ambient_color * lights.ambient_color
     diffuse_color = materials.diffuse_color * light_diffuse
     specular_color = materials.specular_color * light_specular
+
     if normals.dim() == 2 and points.dim() == 2:
         # If given packed inputs remove batch dim in output.
         return (
             ambient_color.squeeze(),
             diffuse_color.squeeze(),
             specular_color.squeeze(),
         )
+
+    if ambient_color.ndim != diffuse_color.ndim:
+        # Reshape from (N, 3) to have dimensions compatible with
+        # diffuse_color which is of shape (N, H, W, K, 3)
+        ambient_color = ambient_color[:, None, None, None, :]
     return ambient_color, diffuse_color, specular_color
 
 

tests/test_render_meshes.py

@@ -6,6 +6,7 @@
 """
 import os
 import unittest
+from collections import namedtuple
 
 import numpy as np
 import torch
@@ -53,6 +54,8 @@
 DATA_DIR = get_tests_dir() / "data"
 TUTORIAL_DATA_DIR = get_pytorch3d_dir() / "docs/tutorials/data"
 
+ShaderTest = namedtuple("ShaderTest", ["shader", "reference_name", "debug_name"])
+
 
 class TestRenderMeshes(TestCaseMixin, unittest.TestCase):
     def test_simple_sphere(self, elevated_camera=False, check_depth=False):
@@ -107,13 +110,13 @@ def test_simple_sphere(self, elevated_camera=False, check_depth=False):
             blend_params = BlendParams(1e-4, 1e-4, (0, 0, 0))
 
             # Test several shaders
-            shaders = {
-                "phong": HardPhongShader,
-                "gouraud": HardGouraudShader,
-                "flat": HardFlatShader,
-            }
-            for (name, shader_init) in shaders.items():
-                shader = shader_init(
+            shader_tests = [
+                ShaderTest(HardPhongShader, "phong", "hard_phong"),
+                ShaderTest(HardGouraudShader, "gouraud", "hard_gouraud"),
+                ShaderTest(HardFlatShader, "flat", "hard_flat"),
+            ]
+            for test in shader_tests:
+                shader = test.shader(
                     lights=lights,
                     cameras=cameras,
                     materials=materials,
@@ -135,7 +138,7 @@ def test_simple_sphere(self, elevated_camera=False, check_depth=False):
 
                 rgb = images[0, ..., :3].squeeze().cpu()
                 filename = "simple_sphere_light_%s%s%s.png" % (
-                    name,
+                    test.reference_name,
                     postfix,
                     cam_type.__name__,
                 )
@@ -144,7 +147,12 @@ def test_simple_sphere(self, elevated_camera=False, check_depth=False):
                 self.assertClose(rgb, image_ref, atol=0.05)
 
                 if DEBUG:
-                    filename = "DEBUG_%s" % filename
+                    debug_filename = "simple_sphere_light_%s%s%s.png" % (
+                        test.debug_name,
+                        postfix,
+                        cam_type.__name__,
+                    )
+                    filename = "DEBUG_%s" % debug_filename
                     Image.fromarray((rgb.numpy() * 255).astype(np.uint8)).save(
                         DATA_DIR / filename
                     )
@@ -269,7 +277,8 @@ def test_simple_sphere_screen(self):
     def test_simple_sphere_batched(self):
         """
         Test a mesh with vertex textures can be extended to form a batch, and
-        is rendered correctly with Phong, Gouraud and Flat Shaders.
+        is rendered correctly with Phong, Gouraud and Flat Shaders with batched
+        lighting and hard and soft blending.
         """
         batch_size = 5
         device = torch.device("cuda:0")
@@ -291,24 +300,28 @@ def test_simple_sphere_batched(self):
         R, T = look_at_view_transform(dist, elev, azim)
         cameras = FoVPerspectiveCameras(device=device, R=R, T=T)
         raster_settings = RasterizationSettings(
-            image_size=512, blur_radius=0.0, faces_per_pixel=1
+            image_size=512, blur_radius=0.0, faces_per_pixel=4
         )
 
         # Init shader settings
         materials = Materials(device=device)
-        lights = PointLights(device=device)
-        lights.location = torch.tensor([0.0, 0.0, +2.0], device=device)[None]
+        lights_location = torch.tensor([0.0, 0.0, +2.0], device=device)
+        lights_location = lights_location[None].expand(batch_size, -1)
+        lights = PointLights(device=device, location=lights_location)
         blend_params = BlendParams(1e-4, 1e-4, (0, 0, 0))
 
         # Init renderer
         rasterizer = MeshRasterizer(cameras=cameras, raster_settings=raster_settings)
-        shaders = {
-            "phong": HardPhongShader,
-            "gouraud": HardGouraudShader,
-            "flat": HardFlatShader,
-        }
-        for (name, shader_init) in shaders.items():
-            shader = shader_init(
+        shader_tests = [
+            ShaderTest(HardPhongShader, "phong", "hard_phong"),
+            ShaderTest(SoftPhongShader, "phong", "soft_phong"),
+            ShaderTest(HardGouraudShader, "gouraud", "hard_gouraud"),
+            ShaderTest(HardFlatShader, "flat", "hard_flat"),
+        ]
+        for test in shader_tests:
+            reference_name = test.reference_name
+            debug_name = test.debug_name
+            shader = test.shader(
                 lights=lights,
                 cameras=cameras,
                 materials=materials,
@@ -317,14 +330,15 @@ def test_simple_sphere_batched(self):
             renderer = MeshRenderer(rasterizer=rasterizer, shader=shader)
             images = renderer(sphere_meshes)
             image_ref = load_rgb_image(
-                "test_simple_sphere_light_%s_%s.png" % (name, type(cameras).__name__),
+                "test_simple_sphere_light_%s_%s.png"
+                % (reference_name, type(cameras).__name__),
                 DATA_DIR,
             )
             for i in range(batch_size):
                 rgb = images[i, ..., :3].squeeze().cpu()
                 if i == 0 and DEBUG:
                     filename = "DEBUG_simple_sphere_batched_%s_%s.png" % (
-                        name,
+                        debug_name,
                         type(cameras).__name__,
                     )
                     Image.fromarray((rgb.numpy() * 255).astype(np.uint8)).save(