File size: 13,703 Bytes
11e6f7b
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
# SPDX-FileCopyrightText: Copyright (c) 2021-2022 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: LicenseRef-NvidiaProprietary
#
# NVIDIA CORPORATION, its affiliates and licensors retain all intellectual
# property and proprietary rights in and to this material, related
# documentation and any modifications thereto. Any use, reproduction,
# disclosure or distribution of this material and related documentation
# without an express license agreement from NVIDIA CORPORATION or
# its affiliates is strictly prohibited.
"""
The ray sampler is a module that takes in camera matrices and resolution and batches of rays.
Expects cam2world matrices that use the OpenCV camera coordinate system conventions.
"""

import torch
from pdb import set_trace as st
import random

HUGE_NUMBER = 1e10
TINY_NUMBER = 1e-6  # float32 only has 7 decimal digits precision


######################################################################################
# wrapper to simplify the use of nerfnet
######################################################################################
# https://github.com/Kai-46/nerfplusplus/blob/ebf2f3e75fd6c5dfc8c9d0b533800daaf17bd95f/ddp_model.py#L16
def depth2pts_outside(ray_o, ray_d, depth):
    '''
    ray_o, ray_d: [..., 3]
    depth: [...]; inverse of distance to sphere origin
    '''
    # note: d1 becomes negative if this mid point is behind camera
    d1 = -torch.sum(ray_d * ray_o, dim=-1) / torch.sum(ray_d * ray_d, dim=-1)
    p_mid = ray_o + d1.unsqueeze(-1) * ray_d
    p_mid_norm = torch.norm(p_mid, dim=-1)
    ray_d_cos = 1. / torch.norm(ray_d, dim=-1)
    d2 = torch.sqrt(1. - p_mid_norm * p_mid_norm) * ray_d_cos
    p_sphere = ray_o + (d1 + d2).unsqueeze(-1) * ray_d

    rot_axis = torch.cross(ray_o, p_sphere, dim=-1)
    rot_axis = rot_axis / torch.norm(rot_axis, dim=-1, keepdim=True)
    phi = torch.asin(p_mid_norm)
    theta = torch.asin(p_mid_norm * depth)  # depth is inside [0, 1]
    rot_angle = (phi - theta).unsqueeze(-1)  # [..., 1]

    # now rotate p_sphere
    # Rodrigues formula: https://en.wikipedia.org/wiki/Rodrigues%27_rotation_formula
    p_sphere_new = p_sphere * torch.cos(rot_angle) + \
                   torch.cross(rot_axis, p_sphere, dim=-1) * torch.sin(rot_angle) + \
                   rot_axis * torch.sum(rot_axis*p_sphere, dim=-1, keepdim=True) * (1.-torch.cos(rot_angle))
    p_sphere_new = p_sphere_new / torch.norm(
        p_sphere_new, dim=-1, keepdim=True)
    pts = torch.cat((p_sphere_new, depth.unsqueeze(-1)), dim=-1)

    # now calculate conventional depth
    depth_real = 1. / (depth + TINY_NUMBER) * torch.cos(theta) * ray_d_cos + d1
    return pts, depth_real


class RaySampler(torch.nn.Module):

    def __init__(self):
        super().__init__()
        self.ray_origins_h, self.ray_directions, self.depths, self.image_coords, self.rendering_options = None, None, None, None, None

    def create_patch_uv(self,
                        patch_resolution,
                        resolution,
                        cam2world_matrix,
                        fg_bbox=None):

        def sample_patch_uv(fg_bbox=None):
            assert patch_resolution <= resolution

            def sample_patch_range():
                patch_reolution_start = random.randint(
                    0, resolution -
                    patch_resolution)  # alias for randrange(start, stop+1)
                # patch_reolution_end = patch_reolution_start + patch_resolution
                return patch_reolution_start  # , patch_reolution_end

            def sample_patch_range_oversample_boundary(range_start=None,
                                                       range_end=None):
                # left down corner undersampled
                if range_start is None:
                    # range_start = patch_resolution // 2
                    range_start = patch_resolution
                if range_end is None:
                    # range_end = resolution + patch_resolution // 2
                    range_end = resolution + patch_resolution

                # oversample the boundary
                patch_reolution_end = random.randint(
                    range_start,
                    range_end,
                )

                # clip range
                if patch_reolution_end <= patch_resolution:
                    patch_reolution_end = patch_resolution
                elif patch_reolution_end > resolution:
                    patch_reolution_end = resolution

                # patch_reolution_end = patch_reolution_start + patch_resolution
                return patch_reolution_end  # , patch_reolution_end

            # h_start = sample_patch_range()
            # assert fg_bbox is not None
            if fg_bbox is not None and random.random(
            ) > 0.125:  # only train foreground. Has 0.1 prob to sample/train background.
                # if fg_bbox is not None: # only train foreground. Has 0.1 prob to sample/train background.
                # only return one UV here
                top_min, left_min = fg_bbox[:, :2].min(dim=0,
                                                       keepdim=True)[0][0]
                height_max, width_max = fg_bbox[:, 2:].max(dim=0,
                                                           keepdim=True)[0][0]

                if top_min + patch_resolution < height_max:
                    h_end = sample_patch_range_oversample_boundary(
                        top_min + patch_resolution, height_max)
                else:
                    h_end = max(
                        height_max.to(torch.uint8).item(), patch_resolution)
                if left_min + patch_resolution < width_max:
                    w_end = sample_patch_range_oversample_boundary(
                        left_min + patch_resolution, width_max)
                else:
                    w_end = max(
                        width_max.to(torch.uint8).item(), patch_resolution)

                h_start = h_end - patch_resolution
                w_start = w_end - patch_resolution

                try:
                    assert h_start >= 0 and w_start >= 0
                except:
                    st()

            else:
                h_end = sample_patch_range_oversample_boundary()
                h_start = h_end - patch_resolution
                w_end = sample_patch_range_oversample_boundary()
                w_start = w_end - patch_resolution

                assert h_start >= 0 and w_start >= 0

            uv = torch.stack(
                torch.meshgrid(
                    torch.arange(
                        start=h_start,
                        # end=h_start+patch_resolution,
                        end=h_end,
                        dtype=torch.float32,
                        device=cam2world_matrix.device),
                    torch.arange(
                        start=w_start,
                        #  end=w_start + patch_resolution,
                        end=w_end,
                        dtype=torch.float32,
                        device=cam2world_matrix.device),
                    indexing='ij')) * (1. / resolution) + (0.5 / resolution)

            uv = uv.flip(0).reshape(2, -1).transpose(1, 0)  # ij -> xy

            return uv, (h_start, w_start, patch_resolution, patch_resolution
                        )  # top: int, left: int, height: int, width: int

        all_uv = []
        ray_bboxes = []
        for _ in range(cam2world_matrix.shape[0]):
            uv, bbox = sample_patch_uv(fg_bbox)
            all_uv.append(uv)
            ray_bboxes.append(bbox)

        all_uv = torch.stack(all_uv, 0)  # B patch_res**2 2
        # ray_bboxes = torch.stack(ray_bboxes, 0) # B patch_res**2 2

        return all_uv, ray_bboxes

    def create_uv(self, resolution, cam2world_matrix):

        uv = torch.stack(
            torch.meshgrid(torch.arange(resolution,
                                        dtype=torch.float32,
                                        device=cam2world_matrix.device),
                           torch.arange(resolution,
                                        dtype=torch.float32,
                                        device=cam2world_matrix.device),
                           indexing='ij')) * (1. / resolution) + (0.5 /
                                                                  resolution)

        uv = uv.flip(0).reshape(2, -1).transpose(1, 0)  # why
        uv = uv.unsqueeze(0).repeat(cam2world_matrix.shape[0], 1, 1)

        return uv

    def forward(self, cam2world_matrix, intrinsics, resolution, fg_mask=None):
        """
        Create batches of rays and return origins and directions.

        cam2world_matrix: (N, 4, 4)
        intrinsics: (N, 3, 3)
        resolution: int

        ray_origins: (N, M, 3)
        ray_dirs: (N, M, 2)
        """
        N, M = cam2world_matrix.shape[0], resolution**2
        cam_locs_world = cam2world_matrix[:, :3, 3]
        fx = intrinsics[:, 0, 0]
        fy = intrinsics[:, 1, 1]
        cx = intrinsics[:, 0, 2]
        cy = intrinsics[:, 1, 2]
        sk = intrinsics[:, 0, 1]

        # uv = torch.stack(
        #     torch.meshgrid(torch.arange(resolution,
        #                                 dtype=torch.float32,
        #                                 device=cam2world_matrix.device),
        #                    torch.arange(resolution,
        #                                 dtype=torch.float32,
        #                                 device=cam2world_matrix.device),
        #                    indexing='ij')) * (1. / resolution) + (0.5 /
        #                                                           resolution)
        # uv = uv.flip(0).reshape(2, -1).transpose(1, 0)  # why
        # uv = uv.unsqueeze(0).repeat(cam2world_matrix.shape[0], 1, 1)
        uv = self.create_uv(
            resolution,
            cam2world_matrix,
        )

        x_cam = uv[:, :, 0].view(N, -1)
        y_cam = uv[:, :, 1].view(N, -1)  # [0,1] range
        z_cam = torch.ones((N, M), device=cam2world_matrix.device)

        # basically torch.inverse(intrinsics)
        x_lift = (x_cam - cx.unsqueeze(-1) + cy.unsqueeze(-1) *
                  sk.unsqueeze(-1) / fy.unsqueeze(-1) - sk.unsqueeze(-1) *
                  y_cam / fy.unsqueeze(-1)) / fx.unsqueeze(-1) * z_cam
        y_lift = (y_cam - cy.unsqueeze(-1)) / fy.unsqueeze(-1) * z_cam

        cam_rel_points = torch.stack(
            (x_lift, y_lift, z_cam, torch.ones_like(z_cam)), dim=-1)

        # st()

        world_rel_points = torch.bmm(cam2world_matrix,
                                     cam_rel_points.permute(0, 2, 1)).permute(
                                         0, 2, 1)[:, :, :3]

        ray_dirs = world_rel_points - cam_locs_world[:, None, :]
        ray_dirs = torch.nn.functional.normalize(ray_dirs, dim=2)

        ray_origins = cam_locs_world.unsqueeze(1).repeat(
            1, ray_dirs.shape[1], 1)

        return ray_origins, ray_dirs, None


class PatchRaySampler(RaySampler):

    def forward(self,
                cam2world_matrix,
                intrinsics,
                patch_resolution,
                resolution,
                fg_bbox=None):
        """
        Create batches of rays and return origins and directions.

        cam2world_matrix: (N, 4, 4)
        intrinsics: (N, 3, 3)
        resolution: int

        ray_origins: (N, M, 3)
        ray_dirs: (N, M, 2)
        """
        N, M = cam2world_matrix.shape[0], patch_resolution**2
        cam_locs_world = cam2world_matrix[:, :3, 3]
        fx = intrinsics[:, 0, 0]
        fy = intrinsics[:, 1, 1]
        cx = intrinsics[:, 0, 2]
        cy = intrinsics[:, 1, 2]
        sk = intrinsics[:, 0, 1]

        # uv = self.create_uv(resolution, cam2world_matrix)

        # all_uv, ray_bboxes = self.create_patch_uv(
        all_uv_list = []
        ray_bboxes = []
        for idx in range(N):
            uv, bboxes = self.create_patch_uv(
                patch_resolution, resolution, cam2world_matrix[idx:idx + 1],
                fg_bbox[idx:idx + 1]
                if fg_bbox is not None else None)  # for debugging, hard coded
            all_uv_list.append(
                uv
                # cam2world_matrix[idx:idx+1], )[0]  # for debugging, hard coded
            )
            ray_bboxes.extend(bboxes)
        all_uv = torch.cat(all_uv_list, 0)
        # ray_bboxes = torch.cat(ray_bboxes_list, 0)
        # all_uv, _ = self.create_patch_uv(
        #     patch_resolution, resolution,
        #     cam2world_matrix, fg_bbox)  # for debugging, hard coded
        # st()

        x_cam = all_uv[:, :, 0].view(N, -1)
        y_cam = all_uv[:, :, 1].view(N, -1)  # [0,1] range
        z_cam = torch.ones((N, M), device=cam2world_matrix.device)

        # basically torch.inverse(intrinsics)
        x_lift = (x_cam - cx.unsqueeze(-1) + cy.unsqueeze(-1) *
                  sk.unsqueeze(-1) / fy.unsqueeze(-1) - sk.unsqueeze(-1) *
                  y_cam / fy.unsqueeze(-1)) / fx.unsqueeze(-1) * z_cam
        y_lift = (y_cam - cy.unsqueeze(-1)) / fy.unsqueeze(-1) * z_cam

        cam_rel_points = torch.stack(
            (x_lift, y_lift, z_cam, torch.ones_like(z_cam)), dim=-1)

        world_rel_points = torch.bmm(cam2world_matrix,
                                     cam_rel_points.permute(0, 2, 1)).permute(
                                         0, 2, 1)[:, :, :3]

        ray_dirs = world_rel_points - cam_locs_world[:, None, :]
        ray_dirs = torch.nn.functional.normalize(ray_dirs, dim=2)

        ray_origins = cam_locs_world.unsqueeze(1).repeat(
            1, ray_dirs.shape[1], 1)

        return ray_origins, ray_dirs, ray_bboxes