File size: 24,490 Bytes
7088d16
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {},
    "colab_type": "code",
    "id": "_Ip8kp4TfBLZ"
   },
   "outputs": [],
   "source": [
    "# Copyright (c) Meta Platforms, Inc. and affiliates. All rights reserved."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "kuXHJv44fBLe"
   },
   "source": [
    "# Render a textured mesh\n",
    "\n",
    "This tutorial shows how to:\n",
    "- load a mesh and textures from an `.obj` file. \n",
    "- set up a renderer \n",
    "- render the mesh \n",
    "- vary the rendering settings such as lighting and camera position\n",
    "- use the batching features of the pytorch3d API to render the mesh from different viewpoints"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "Bnj3THhzfBLf"
   },
   "source": [
    "## 0. Install and Import modules"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "okLalbR_g7NS"
   },
   "source": [
    "Ensure `torch` and `torchvision` are installed. If `pytorch3d` is not installed, install it using the following cell:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {
     "base_uri": "https://localhost:8080/",
     "height": 717
    },
    "colab_type": "code",
    "id": "musUWTglgxSB",
    "outputId": "16d1a1b2-3f7f-43ed-ca28-a4d236cc0572"
   },
   "outputs": [],
   "source": [
    "import os\n",
    "import sys\n",
    "import torch\n",
    "import subprocess\n",
    "need_pytorch3d=False\n",
    "try:\n",
    "    import pytorch3d\n",
    "except ModuleNotFoundError:\n",
    "    need_pytorch3d=True\n",
    "if need_pytorch3d:\n",
    "    pyt_version_str=torch.__version__.split(\"+\")[0].replace(\".\", \"\")\n",
    "    version_str=\"\".join([\n",
    "        f\"py3{sys.version_info.minor}_cu\",\n",
    "        torch.version.cuda.replace(\".\",\"\"),\n",
    "        f\"_pyt{pyt_version_str}\"\n",
    "    ])\n",
    "    !pip install fvcore iopath\n",
    "    if sys.platform.startswith(\"linux\"):\n",
    "        print(\"Trying to install wheel for PyTorch3D\")\n",
    "        !pip install --no-index --no-cache-dir pytorch3d -f https://dl.fbaipublicfiles.com/pytorch3d/packaging/wheels/{version_str}/download.html\n",
    "        pip_list = !pip freeze\n",
    "        need_pytorch3d = not any(i.startswith(\"pytorch3d==\") for  i in pip_list)\n",
    "    if need_pytorch3d:\n",
    "        print(f\"failed to find/install wheel for {version_str}\")\n",
    "if need_pytorch3d:\n",
    "    print(\"Installing PyTorch3D from source\")\n",
    "    !pip install ninja\n",
    "    !pip install 'git+https://github.com/facebookresearch/pytorch3d.git@stable'"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {},
    "colab_type": "code",
    "id": "nX99zdoffBLg"
   },
   "outputs": [],
   "source": [
    "import os\n",
    "import torch\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "# Util function for loading meshes\n",
    "from pytorch3d.io import load_objs_as_meshes, load_obj\n",
    "\n",
    "# Data structures and functions for rendering\n",
    "from pytorch3d.structures import Meshes\n",
    "from pytorch3d.vis.plotly_vis import AxisArgs, plot_batch_individually, plot_scene\n",
    "from pytorch3d.vis.texture_vis import texturesuv_image_matplotlib\n",
    "from pytorch3d.renderer import (\n",
    "    look_at_view_transform,\n",
    "    FoVPerspectiveCameras, \n",
    "    PointLights, \n",
    "    DirectionalLights, \n",
    "    Materials, \n",
    "    RasterizationSettings, \n",
    "    MeshRenderer, \n",
    "    MeshRasterizer,  \n",
    "    SoftPhongShader,\n",
    "    TexturesUV,\n",
    "    TexturesVertex\n",
    ")\n",
    "\n",
    "# add path for demo utils functions \n",
    "import sys\n",
    "import os\n",
    "sys.path.append(os.path.abspath(''))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "Lxmehq6Zhrzv"
   },
   "source": [
    "If using **Google Colab**, fetch the utils file for plotting image grids:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {
     "base_uri": "https://localhost:8080/",
     "height": 204
    },
    "colab_type": "code",
    "id": "HZozr3Pmho-5",
    "outputId": "be5eb60d-5f65-4db1-cca0-44ee68c8f5fd"
   },
   "outputs": [],
   "source": [
    "!wget https://raw.githubusercontent.com/facebookresearch/pytorch3d/main/docs/tutorials/utils/plot_image_grid.py\n",
    "from plot_image_grid import image_grid"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "g4B62MzYiJUM"
   },
   "source": [
    "OR if running **locally** uncomment and run the following cell:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {},
    "colab_type": "code",
    "id": "paJ4Im8ahl7O"
   },
   "outputs": [],
   "source": [
    "# from utils import image_grid"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "5jGq772XfBLk"
   },
   "source": [
    "### 1. Load a mesh and texture file\n",
    "\n",
    "Load an `.obj` file and its associated `.mtl` file and create a **Textures** and **Meshes** object. \n",
    "\n",
    "**Meshes** is a unique datastructure provided in PyTorch3D for working with batches of meshes of different sizes. \n",
    "\n",
    "**TexturesUV** is an auxiliary datastructure for storing vertex uv and texture maps for meshes. \n",
    "\n",
    "**Meshes** has several class methods which are used throughout the rendering pipeline."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "a8eU4zo5jd_H"
   },
   "source": [
    "If running this notebook using **Google Colab**, run the following cell to fetch the mesh obj and texture files and save it at the path `data/cow_mesh`:\n",
    "If running locally, the data is already available at the correct path. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {
     "base_uri": "https://localhost:8080/",
     "height": 578
    },
    "colab_type": "code",
    "id": "tTm0cVuOjb1W",
    "outputId": "6cd7e2ec-65e1-4dcc-99e8-c347bc504f0a"
   },
   "outputs": [],
   "source": [
    "!mkdir -p data/cow_mesh\n",
    "!wget -P data/cow_mesh https://dl.fbaipublicfiles.com/pytorch3d/data/cow_mesh/cow.obj\n",
    "!wget -P data/cow_mesh https://dl.fbaipublicfiles.com/pytorch3d/data/cow_mesh/cow.mtl\n",
    "!wget -P data/cow_mesh https://dl.fbaipublicfiles.com/pytorch3d/data/cow_mesh/cow_texture.png"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {},
    "colab_type": "code",
    "id": "gi5Kd0GafBLl"
   },
   "outputs": [],
   "source": [
    "# Setup\n",
    "if torch.cuda.is_available():\n",
    "    device = torch.device(\"cuda:0\")\n",
    "    torch.cuda.set_device(device)\n",
    "else:\n",
    "    device = torch.device(\"cpu\")\n",
    "\n",
    "# Set paths\n",
    "DATA_DIR = \"./data\"\n",
    "obj_filename = os.path.join(DATA_DIR, \"cow_mesh/cow.obj\")\n",
    "\n",
    "# Load obj file\n",
    "mesh = load_objs_as_meshes([obj_filename], device=device)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "5APAQs6-fBLp"
   },
   "source": [
    "#### Let's visualize the texture map"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {
     "base_uri": "https://localhost:8080/",
     "height": 428
    },
    "colab_type": "code",
    "id": "YipUhrIHfBLq",
    "outputId": "48987b1d-5cc1-4c2a-cb3c-713d64f6a38d"
   },
   "outputs": [],
   "source": [
    "plt.figure(figsize=(7,7))\n",
    "texture_image=mesh.textures.maps_padded()\n",
    "plt.imshow(texture_image.squeeze().cpu().numpy())\n",
    "plt.axis(\"off\");"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "PyTorch3D has a built-in way to view the texture map with matplotlib along with the points on the map corresponding to vertices. There is also a method, texturesuv_image_PIL, to get a similar image which can be saved to a file."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "plt.figure(figsize=(7,7))\n",
    "texturesuv_image_matplotlib(mesh.textures, subsample=None)\n",
    "plt.axis(\"off\");"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "GcnG6XJ6fBLu"
   },
   "source": [
    "## 2. Create a renderer\n",
    "\n",
    "A renderer in PyTorch3D is composed of a **rasterizer** and a **shader** which each have a number of subcomponents such as a **camera** (orthographic/perspective). Here we initialize some of these components and use default values for the rest.\n",
    "\n",
    "In this example we will first create a **renderer** which uses a **perspective camera**, a **point light** and applies **Phong shading**. Then we learn how to vary different components using the modular API.  "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {},
    "colab_type": "code",
    "id": "dX466mWnfBLv"
   },
   "outputs": [],
   "source": [
    "# Initialize a camera.\n",
    "# With world coordinates +Y up, +X left and +Z in, the front of the cow is facing the -Z direction. \n",
    "# So we move the camera by 180 in the azimuth direction so it is facing the front of the cow. \n",
    "R, T = look_at_view_transform(2.7, 0, 180) \n",
    "cameras = FoVPerspectiveCameras(device=device, R=R, T=T)\n",
    "\n",
    "# Define the settings for rasterization and shading. Here we set the output image to be of size\n",
    "# 512x512. As we are rendering images for visualization purposes only we will set faces_per_pixel=1\n",
    "# and blur_radius=0.0. We also set bin_size and max_faces_per_bin to None which ensure that \n",
    "# the faster coarse-to-fine rasterization method is used. Refer to rasterize_meshes.py for \n",
    "# explanations of these parameters. Refer to docs/notes/renderer.md for an explanation of \n",
    "# the difference between naive and coarse-to-fine rasterization. \n",
    "raster_settings = RasterizationSettings(\n",
    "    image_size=512, \n",
    "    blur_radius=0.0, \n",
    "    faces_per_pixel=1, \n",
    ")\n",
    "\n",
    "# Place a point light in front of the object. As mentioned above, the front of the cow is facing the \n",
    "# -z direction. \n",
    "lights = PointLights(device=device, location=[[0.0, 0.0, -3.0]])\n",
    "\n",
    "# Create a Phong renderer by composing a rasterizer and a shader. The textured Phong shader will \n",
    "# interpolate the texture uv coordinates for each vertex, sample from a texture image and \n",
    "# apply the Phong lighting model\n",
    "renderer = MeshRenderer(\n",
    "    rasterizer=MeshRasterizer(\n",
    "        cameras=cameras, \n",
    "        raster_settings=raster_settings\n",
    "    ),\n",
    "    shader=SoftPhongShader(\n",
    "        device=device, \n",
    "        cameras=cameras,\n",
    "        lights=lights\n",
    "    )\n",
    ")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "KyOY5qXvfBLz"
   },
   "source": [
    "## 3. Render the mesh"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "8VkRA4qJfBL0"
   },
   "source": [
    "The light is in front of the object so it is bright and the image has specular highlights."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {
     "base_uri": "https://localhost:8080/",
     "height": 592
    },
    "colab_type": "code",
    "id": "gBLZH8iUfBL1",
    "outputId": "cc3cd3f0-189e-4497-ce47-e64b4da542e8"
   },
   "outputs": [],
   "source": [
    "images = renderer(mesh)\n",
    "plt.figure(figsize=(10, 10))\n",
    "plt.imshow(images[0, ..., :3].cpu().numpy())\n",
    "plt.axis(\"off\");"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "k161XF3sfBL5"
   },
   "source": [
    "## 4. Move the light behind the object and re-render\n",
    "\n",
    "We can pass arbitrary keyword arguments to the `rasterizer`/`shader` via the call to the `renderer` so the renderer does not need to be reinitialized if any of the settings change/\n",
    "\n",
    "In this case, we can simply update the location of the lights and pass them into the call to the renderer. \n",
    "\n",
    "The image is now dark as there is only ambient lighting, and there are no specular highlights."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {},
    "colab_type": "code",
    "id": "BdWkkeibfBL6"
   },
   "outputs": [],
   "source": [
    "# Now move the light so it is on the +Z axis which will be behind the cow. \n",
    "lights.location = torch.tensor([0.0, 0.0, +1.0], device=device)[None]\n",
    "images = renderer(mesh, lights=lights)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {
     "base_uri": "https://localhost:8080/",
     "height": 592
    },
    "colab_type": "code",
    "id": "UmV3j1YffBL9",
    "outputId": "2e8edca0-5bd8-4a2f-a160-83c4b0520123"
   },
   "outputs": [],
   "source": [
    "plt.figure(figsize=(10, 10))\n",
    "plt.imshow(images[0, ..., :3].cpu().numpy())\n",
    "plt.axis(\"off\");"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "t93aVotMfBMB"
   },
   "source": [
    "## 5. Rotate the object, modify the material properties or light properties\n",
    "\n",
    "We can also change many other settings in the rendering pipeline. Here we:\n",
    "\n",
    "- change the **viewing angle** of the camera\n",
    "- change the **position** of the point light\n",
    "- change the **material reflectance** properties of the mesh"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {},
    "colab_type": "code",
    "id": "4mYXYziefBMB"
   },
   "outputs": [],
   "source": [
    "# Rotate the object by increasing the elevation and azimuth angles\n",
    "R, T = look_at_view_transform(dist=2.7, elev=10, azim=-150)\n",
    "cameras = FoVPerspectiveCameras(device=device, R=R, T=T)\n",
    "\n",
    "# Move the light location so the light is shining on the cow's face.  \n",
    "lights.location = torch.tensor([[2.0, 2.0, -2.0]], device=device)\n",
    "\n",
    "# Change specular color to green and change material shininess \n",
    "materials = Materials(\n",
    "    device=device,\n",
    "    specular_color=[[0.0, 1.0, 0.0]],\n",
    "    shininess=10.0\n",
    ")\n",
    "\n",
    "# Re render the mesh, passing in keyword arguments for the modified components.\n",
    "images = renderer(mesh, lights=lights, materials=materials, cameras=cameras)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {
     "base_uri": "https://localhost:8080/",
     "height": 592
    },
    "colab_type": "code",
    "id": "rHIxIfh5fBME",
    "outputId": "1ca2d337-2983-478f-b3c9-d64b84ba1a31"
   },
   "outputs": [],
   "source": [
    "plt.figure(figsize=(10, 10))\n",
    "plt.imshow(images[0, ..., :3].cpu().numpy())\n",
    "plt.axis(\"off\");"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "17c4xmtyfBMH"
   },
   "source": [
    "## 6. Batched Rendering\n",
    "\n",
    "One of the core design choices of the PyTorch3D API is to support **batched inputs for all components**. \n",
    "The renderer and associated components can take batched inputs and **render a batch of output images in one forward pass**. We will now use this feature to render the mesh from many different viewpoints.\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {},
    "colab_type": "code",
    "id": "CDQKebNNfBMI"
   },
   "outputs": [],
   "source": [
    "# Set batch size - this is the number of different viewpoints from which we want to render the mesh.\n",
    "batch_size = 20\n",
    "\n",
    "# Create a batch of meshes by repeating the cow mesh and associated textures. \n",
    "# Meshes has a useful `extend` method which allows us do this very easily. \n",
    "# This also extends the textures. \n",
    "meshes = mesh.extend(batch_size)\n",
    "\n",
    "# Get a batch of viewing angles. \n",
    "elev = torch.linspace(0, 180, batch_size)\n",
    "azim = torch.linspace(-180, 180, batch_size)\n",
    "\n",
    "# All the cameras helper methods support mixed type inputs and broadcasting. So we can \n",
    "# view the camera from the same distance and specify dist=2.7 as a float,\n",
    "# and then specify elevation and azimuth angles for each viewpoint as tensors. \n",
    "R, T = look_at_view_transform(dist=2.7, elev=elev, azim=azim)\n",
    "cameras = FoVPerspectiveCameras(device=device, R=R, T=T)\n",
    "\n",
    "# Move the light back in front of the cow which is facing the -z direction.\n",
    "lights.location = torch.tensor([[0.0, 0.0, -3.0]], device=device)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "colab": {},
    "colab_type": "code",
    "id": "gyYJCwEDfBML"
   },
   "outputs": [],
   "source": [
    "# We can pass arbitrary keyword arguments to the rasterizer/shader via the renderer\n",
    "# so the renderer does not need to be reinitialized if any of the settings change.\n",
    "images = renderer(meshes, cameras=cameras, lights=lights)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "image_grid(images.cpu().numpy(), rows=4, cols=5, rgb=True)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 7. Plotly visualization \n",
    "If you only want to visualize a mesh, you don't really need to use a differentiable renderer - instead we support plotting of Meshes with plotly. For these Meshes, we use TexturesVertex to define a texture for the rendering.\n",
    "`plot_meshes` creates a Plotly figure with a trace for each Meshes object. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "verts, faces_idx, _ = load_obj(obj_filename)\n",
    "faces = faces_idx.verts_idx\n",
    "\n",
    "# Initialize each vertex to be white in color.\n",
    "verts_rgb = torch.ones_like(verts)[None]  # (1, V, 3)\n",
    "textures = TexturesVertex(verts_features=verts_rgb.to(device))\n",
    "\n",
    "# Create a Meshes object\n",
    "mesh = Meshes(\n",
    "    verts=[verts.to(device)],   \n",
    "    faces=[faces.to(device)],\n",
    "    textures=textures\n",
    ")\n",
    "\n",
    "# Render the plotly figure\n",
    "fig = plot_scene({\n",
    "    \"subplot1\": {\n",
    "        \"cow_mesh\": mesh\n",
    "    }\n",
    "})\n",
    "fig.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# use Plotly's default colors (no texture)\n",
    "mesh = Meshes(\n",
    "    verts=[verts.to(device)],   \n",
    "    faces=[faces.to(device)]\n",
    ")\n",
    "\n",
    "# Render the plotly figure\n",
    "fig = plot_scene({\n",
    "    \"subplot1\": {\n",
    "        \"cow_mesh\": mesh\n",
    "    }\n",
    "})\n",
    "fig.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# create a batch of meshes, and offset one to prevent overlap\n",
    "mesh_batch = Meshes(\n",
    "    verts=[verts.to(device), (verts + 2).to(device)],   \n",
    "    faces=[faces.to(device), faces.to(device)]\n",
    ")\n",
    "\n",
    "# plot mesh batch in the same trace\n",
    "fig = plot_scene({\n",
    "    \"subplot1\": {\n",
    "        \"cow_mesh_batch\": mesh_batch\n",
    "    }\n",
    "})\n",
    "fig.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot batch of meshes in different traces\n",
    "fig = plot_scene({\n",
    "    \"subplot1\": {\n",
    "        \"cow_mesh1\": mesh_batch[0],\n",
    "        \"cow_mesh2\": mesh_batch[1]\n",
    "    }\n",
    "})\n",
    "fig.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot batch of meshes in different subplots\n",
    "fig = plot_scene({\n",
    "    \"subplot1\": {\n",
    "        \"cow_mesh1\": mesh_batch[0]\n",
    "    },\n",
    "    \"subplot2\":{\n",
    "        \"cow_mesh2\": mesh_batch[1]\n",
    "    }\n",
    "})\n",
    "fig.show()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "For batches, we can also use `plot_batch_individually` to avoid constructing the scene dictionary ourselves."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# extend the batch to have 4 meshes\n",
    "mesh_4 = mesh_batch.extend(2)\n",
    "\n",
    "# visualize the batch in different subplots, 2 per row\n",
    "fig = plot_batch_individually(mesh_4)\n",
    "# we can update the figure height and width\n",
    "fig.update_layout(height=1000, width=500)\n",
    "fig.show()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We can also modify the axis arguments and axis backgrounds in both functions. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "fig2 = plot_scene({\n",
    "    \"cow_plot1\": {\n",
    "        \"cows\": mesh_batch\n",
    "    }\n",
    "},\n",
    "    xaxis={\"backgroundcolor\":\"rgb(200, 200, 230)\"},\n",
    "    yaxis={\"backgroundcolor\":\"rgb(230, 200, 200)\"},\n",
    "    zaxis={\"backgroundcolor\":\"rgb(200, 230, 200)\"}, \n",
    "    axis_args=AxisArgs(showgrid=True))\n",
    "fig2.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "fig3 = plot_batch_individually(\n",
    "    mesh_4, \n",
    "    ncols=2,\n",
    "    subplot_titles = [\"cow1\", \"cow2\", \"cow3\", \"cow4\"], # customize subplot titles\n",
    "    xaxis={\"backgroundcolor\":\"rgb(200, 200, 230)\"},\n",
    "    yaxis={\"backgroundcolor\":\"rgb(230, 200, 200)\"},\n",
    "    zaxis={\"backgroundcolor\":\"rgb(200, 230, 200)\"}, \n",
    "    axis_args=AxisArgs(showgrid=True))\n",
    "fig3.show()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "colab_type": "text",
    "id": "t3qphI1ElUb5"
   },
   "source": [
    "## 8. Conclusion\n",
    "In this tutorial we learnt how to **load** a textured mesh from an obj file, initialize a PyTorch3D datastructure called **Meshes**, set up an **Renderer** consisting of a **Rasterizer** and a **Shader**, and modify several components of the rendering pipeline. We also learned how to render Meshes in Plotly figures."
   ]
  }
 ],
 "metadata": {
  "accelerator": "GPU",
  "anp_metadata": {
   "path": "notebooks/render_textured_meshes.ipynb"
  },
  "bento_stylesheets": {
   "bento/extensions/flow/main.css": true,
   "bento/extensions/kernel_selector/main.css": true,
   "bento/extensions/kernel_ui/main.css": true,
   "bento/extensions/new_kernel/main.css": true,
   "bento/extensions/system_usage/main.css": true,
   "bento/extensions/theme/main.css": true
  },
  "colab": {
   "name": "render_textured_meshes.ipynb",
   "provenance": []
  },
  "disseminate_notebook_info": {
   "backup_notebook_id": "569222367081034"
  },
  "kernelspec": {
   "display_name": "pytorch3d_etc (local)",
   "language": "python",
   "name": "pytorch3d_etc_local"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.7.5+"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 1
}