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new tests demonstrating pixel matching
Summary: Demonstrate current behavior of pixels with new tests of all renderers. Reviewed By: gkioxari Differential Revision: D32651141 fbshipit-source-id: 3ca30b4274ed2699bc5e1a9c6437eb3f0b738cbf
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# Copyright (c) Facebook, Inc. and its affiliates. | ||
# All rights reserved. | ||
# | ||
# This source code is licensed under the BSD-style license found in the | ||
# LICENSE file in the root directory of this source tree. | ||
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import unittest | ||
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import torch | ||
from common_testing import TestCaseMixin | ||
from pytorch3d.renderer import ( | ||
MeshRasterizer, | ||
NDCGridRaysampler, | ||
PerspectiveCameras, | ||
PointsRasterizationSettings, | ||
PointsRasterizer, | ||
PulsarPointsRenderer, | ||
RasterizationSettings, | ||
) | ||
from pytorch3d.structures import Meshes, Pointclouds | ||
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""" | ||
PyTorch3D renderers operate in an align_corners=False manner. | ||
This file demonstrates the pixel-perfect calculation by very simple | ||
examples. | ||
""" | ||
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class _CommonData: | ||
""" | ||
Contains data for all these tests. | ||
- Firstly, a non-square at the origin specified in ndc space and | ||
screen space. Principal point is in the center of the image. | ||
Focal length is 1.0 in world space. | ||
This camera has the identity as its world to view transformation, so | ||
it is facing down the positive z axis with y being up and x being left. | ||
A point on the z=1.0 focal plane has its x,y world coordinate equal to | ||
its NDC. | ||
- Secondly, batched together with that, is a camera with the same | ||
focal length facing in the same direction but located so that it faces | ||
the corner of the corner pixel of the first image, with its principal | ||
point located at its corner, so that it maps the z=1 plane to NDC just | ||
like the first. | ||
- a single point self.point in world space which is located on a plane 1.0 | ||
in front from the camera which is located exactly in the center | ||
of a known pixel (self.x, self.y), specifically with negative x and slightly | ||
positive y, so it is in the top right quadrant of the image. | ||
- A second batch of cameras defined in screen space which exactly match the | ||
first ones. | ||
So that this data can be copied for making demos, it is easiest to leave | ||
it as a freestanding class. | ||
""" | ||
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def __init__(self): | ||
self.H, self.W = 249, 125 | ||
self.image_size = (self.H, self.W) | ||
self.camera_ndc = PerspectiveCameras( | ||
focal_length=1.0, | ||
image_size=(self.image_size,), | ||
in_ndc=True, | ||
T=torch.tensor([[0.0, 0.0, 0.0], [-1.0, self.H / self.W, 0.0]]), | ||
principal_point=((-0.0, -0.0), (1.0, -self.H / self.W)), | ||
) | ||
# Note how principal point is specifiied | ||
self.camera_screen = PerspectiveCameras( | ||
focal_length=self.W / 2.0, | ||
principal_point=((self.W / 2.0, self.H / 2.0), (0.0, self.H)), | ||
image_size=(self.image_size,), | ||
T=torch.tensor([[0.0, 0.0, 0.0], [-1.0, self.H / self.W, 0.0]]), | ||
in_ndc=False, | ||
) | ||
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# 81 is more than half of 125, 113 is a bit less than half of 249 | ||
self.x, self.y = 81, 113 | ||
self.point = [-0.304, 0.176, 1] | ||
# The point is in the center of pixel (81, 113) | ||
# where pixel (0,0) is the top left. | ||
# 81 is 38/2 pixels over the midpoint (125-1)/2=62 | ||
# and 38/125=0.304 | ||
# 113 is 22/2 pixels under the midpoint (249-1)/2=124 | ||
# and 22/125=0.176 | ||
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class TestPixels(TestCaseMixin, unittest.TestCase): | ||
def test_mesh(self): | ||
data = _CommonData() | ||
# Three points on the plane at unit 1 from the camera in | ||
# world space, whose mean is the known point. | ||
verts = torch.tensor( | ||
[[-0.288, 0.192, 1], [-0.32, 0.192, 1], [-0.304, 0.144, 1]] | ||
) | ||
self.assertClose(verts.mean(0), torch.tensor(data.point)) | ||
faces = torch.LongTensor([[0, 1, 2]]) | ||
# A mesh of one triangular face whose centroid is the known point | ||
# duplicated so it can be rendered from two cameras. | ||
meshes = Meshes(verts=[verts], faces=[faces]).extend(2) | ||
faces_per_pixel = 2 | ||
for camera in (data.camera_ndc, data.camera_screen): | ||
rasterizer = MeshRasterizer( | ||
cameras=camera, | ||
raster_settings=RasterizationSettings( | ||
image_size=data.image_size, faces_per_pixel=faces_per_pixel | ||
), | ||
) | ||
barycentric_coords_found = rasterizer(meshes).bary_coords | ||
self.assertTupleEqual( | ||
barycentric_coords_found.shape, | ||
(2,) + data.image_size + (faces_per_pixel, 3), | ||
) | ||
# We see that the barycentric coordinates at the expected | ||
# pixel are (1/3, 1/3, 1/3), indicating that this pixel | ||
# hits the centroid of the triangle. | ||
self.assertClose( | ||
barycentric_coords_found[:, data.y, data.x, 0], | ||
torch.full((2, 3), 1 / 3.0), | ||
atol=1e-5, | ||
) | ||
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def test_pointcloud(self): | ||
data = _CommonData() | ||
clouds = Pointclouds(points=torch.tensor([[data.point]])).extend(2) | ||
colorful_cloud = Pointclouds( | ||
points=torch.tensor([[data.point]]), features=torch.ones(1, 1, 3) | ||
).extend(2) | ||
points_per_pixel = 2 | ||
# for camera in [data.camera_screen]: | ||
for camera in (data.camera_ndc, data.camera_screen): | ||
rasterizer = PointsRasterizer( | ||
cameras=camera, | ||
raster_settings=PointsRasterizationSettings( | ||
image_size=data.image_size, | ||
radius=0.0001, | ||
points_per_pixel=points_per_pixel, | ||
), | ||
) | ||
# when rasterizing we expect only one pixel to be occupied | ||
rasterizer_output = rasterizer(clouds).idx | ||
self.assertTupleEqual( | ||
rasterizer_output.shape, (2,) + data.image_size + (points_per_pixel,) | ||
) | ||
found = torch.nonzero(rasterizer_output != -1) | ||
self.assertTupleEqual(found.shape, (2, 4)) | ||
self.assertListEqual(found[0].tolist(), [0, data.y, data.x, 0]) | ||
self.assertListEqual(found[1].tolist(), [1, data.y, data.x, 0]) | ||
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if camera.in_ndc(): | ||
# Pulsar not currently working in screen space. | ||
pulsar_renderer = PulsarPointsRenderer(rasterizer=rasterizer) | ||
pulsar_output = pulsar_renderer( | ||
colorful_cloud, gamma=(0.1, 0.1), znear=(0.1, 0.1), zfar=(70, 70) | ||
) | ||
self.assertTupleEqual( | ||
pulsar_output.shape, (2,) + data.image_size + (3,) | ||
) | ||
# Look for points rendered in the red channel only, expecting our one. | ||
# Check the first batch element only. | ||
# TODO: Something is odd with the second. | ||
found = torch.nonzero(pulsar_output[0, :, :, 0]) | ||
self.assertTupleEqual(found.shape, (1, 2)) | ||
self.assertListEqual(found[0].tolist(), [data.y, data.x]) | ||
# Should be: | ||
# found = torch.nonzero(pulsar_output[:, :, :, 0]) | ||
# self.assertTupleEqual(found.shape, (2, 3)) | ||
# self.assertListEqual(found[0].tolist(), [0, data.y, data.x]) | ||
# self.assertListEqual(found[1].tolist(), [1, data.y, data.x]) | ||
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def test_raysampler(self): | ||
data = _CommonData() | ||
gridsampler = NDCGridRaysampler( | ||
image_width=data.W, | ||
image_height=data.H, | ||
n_pts_per_ray=2, | ||
min_depth=1.0, | ||
max_depth=2.0, | ||
) | ||
for camera in (data.camera_ndc, data.camera_screen): | ||
bundle = gridsampler(camera) | ||
self.assertTupleEqual(bundle.xys.shape, (2,) + data.image_size + (2,)) | ||
self.assertTupleEqual( | ||
bundle.directions.shape, (2,) + data.image_size + (3,) | ||
) | ||
self.assertClose( | ||
bundle.xys[:, data.y, data.x], | ||
torch.tensor(data.point[:2]).expand(2, -1), | ||
) | ||
# We check only the first batch element. | ||
# Second element varies because of camera location. | ||
self.assertClose( | ||
bundle.directions[0, data.y, data.x], | ||
torch.tensor(data.point), | ||
) | ||
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def test_camera(self): | ||
data = _CommonData() | ||
# Our point, plus the image center, and a corner of the image. | ||
# Located at the focal-length distance away | ||
points = torch.tensor([data.point, [0, 0, 1], [1, data.H / data.W, 1]]) | ||
for cameras in (data.camera_ndc, data.camera_screen): | ||
ndc_points = cameras.transform_points_ndc(points) | ||
screen_points = cameras.transform_points_screen(points) | ||
camera_points = cameras.transform_points(points) | ||
for batch_idx in range(2): | ||
# NDC space agrees with the original | ||
self.assertClose(ndc_points[batch_idx], points, atol=1e-5) | ||
# First point in screen space is the center of our expected pixel | ||
self.assertClose( | ||
screen_points[batch_idx][0], | ||
torch.tensor([data.x + 0.5, data.y + 0.5, 1.0]), | ||
atol=1e-5, | ||
) | ||
# Second point in screen space is the center of the screen | ||
self.assertClose( | ||
screen_points[batch_idx][1], | ||
torch.tensor([data.W / 2.0, data.H / 2.0, 1.0]), | ||
atol=1e-5, | ||
) | ||
# Third point in screen space is the corner of the screen | ||
# (corner of corner pixels) | ||
self.assertClose( | ||
screen_points[batch_idx][2], | ||
torch.tensor([0.0, 0.0, 1.0]), | ||
atol=1e-5, | ||
) | ||
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if cameras.in_ndc(): | ||
self.assertClose(camera_points[batch_idx], ndc_points[batch_idx]) | ||
else: | ||
# transform_points does something strange for screen cameras | ||
if batch_idx == 0: | ||
wanted = torch.stack( | ||
[ | ||
data.W - screen_points[batch_idx, :, 0], | ||
data.H - screen_points[batch_idx, :, 1], | ||
torch.ones(3), | ||
], | ||
dim=1, | ||
) | ||
else: | ||
wanted = torch.stack( | ||
[ | ||
-screen_points[batch_idx, :, 0], | ||
2 * data.H - screen_points[batch_idx, :, 1], | ||
torch.ones(3), | ||
], | ||
dim=1, | ||
) | ||
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print(wanted) | ||
print(camera_points[batch_idx]) | ||
self.assertClose(camera_points[batch_idx], wanted) |