Any obvious reason why my rendered images are all black?

[rrothenb]

Sorry to be a bother but I've been unable so far to figure this out on my own.

I've been using mitsuba 2 for a while now and would like to move to 3. I'm using a scene that works fine with mitsuba 2 (though I've also tried this with various scenes from tutorials/scenes). I'm on apple silicon (m1 ultra) and mitsuba 3 seems to build and run just fine with no complaints:

2023-01-15 14:19:49 INFO  main  [mitsuba.cpp:332] Mitsuba version 3.1.1 (master[71185640], Mac OS, 64bit, 20 threads, 4-wide SIMD)
2023-01-15 14:19:49 INFO  main  [mitsuba.cpp:333] Copyright 2022, Realistic Graphics Lab, EPFL
2023-01-15 14:19:49 INFO  main  [mitsuba.cpp:334] Enabled processor features: llvm sse4.2 x86_64
2023-01-15 14:19:49 INFO  main  [xml.cpp:1433] Loading XML file "test.xml" with variant "scalar_rgb"..
2023-01-15 14:19:49 INFO  main  [xml.cpp:672] Loading included XML file "/Users/rrothenb/dev/mitsuba3/sensor.xml" ..
2023-01-15 14:19:49 DEBUG main  [PluginManager] Loading plugin "plugins/srgb.dylib" ..
2023-01-15 14:19:49 DEBUG main  [PluginManager] Loading plugin "plugins/multijitter.dylib" ..
2023-01-15 14:19:49 DEBUG wrk0  [PluginManager] Loading plugin "plugins/lanczos.dylib" ..
2023-01-15 14:19:49 DEBUG wrk0  [PluginManager] Loading plugin "plugins/hdrfilm.dylib" ..
2023-01-15 14:19:49 DEBUG wrk2  [PluginManager] Loading plugin "plugins/volpathmis.dylib" ..
2023-01-15 14:19:49 DEBUG wrk3  [PluginManager] Loading plugin "plugins/hg.dylib" ..
2023-01-15 14:19:49 DEBUG wrk4  [PluginManager] Loading plugin "plugins/roughplastic.dylib" ..
2023-01-15 14:19:49 DEBUG wrk6  [PluginManager] Loading plugin "plugins/bitmap.dylib" ..
2023-01-15 14:19:49 DEBUG wrk6  [BitmapTexture] Loading bitmap texture from "mitsuba.blend.rgbe" ..
2023-01-15 14:19:49 DEBUG wrk8  [PluginManager] Loading plugin "plugins/roughconductor.dylib" ..
2023-01-15 14:19:49 DEBUG wrk6  [Bitmap] Loading RGBE file "/Users/rrothenb/dev/mitsuba3/mitsuba.blend.rgbe" (11726x9937, rgb, float32) ..
2023-01-15 14:19:49 DEBUG wrk1  [PluginManager] Loading plugin "plugins/envmap.dylib" ..
2023-01-15 14:19:49 DEBUG wrk0  [PluginManager] Loading plugin "plugins/thinlens.dylib" ..
2023-01-15 14:19:49 DEBUG wrk1  [Bitmap] Loading RGBE file "/Users/rrothenb/dev/mitsuba3/mitsuba.rgbe" (7071x7071, rgb, float32) ..
2023-01-15 14:19:49 DEBUG wrk3  [PluginManager] Loading plugin "plugins/homogeneous.dylib" ..
2023-01-15 14:19:49 DEBUG wrk8  [PluginManager] Loading plugin "plugins/uniform.dylib" ..
2023-01-15 14:19:49 DEBUG wrk8  [PluginManager] Loading plugin "plugins/twosided.dylib" ..
2023-01-15 14:19:49 DEBUG wrk3  [PluginManager] Loading plugin "plugins/constvolume.dylib" ..
2023-01-15 14:19:49 DEBUG wrk4  [PluginManager] Loading plugin "plugins/blendbsdf.dylib" ..
2023-01-15 14:19:51 DEBUG wrk1  [PluginManager] Loading plugin "plugins/d65.dylib" ..
2023-01-15 14:19:51 DEBUG wrk1  [PluginManager] Loading plugin "plugins/regular.dylib" ..
2023-01-15 14:19:54 DEBUG wrk6  [PluginManager] Loading plugin "plugins/ply.dylib" ..
2023-01-15 14:19:54 DEBUG wrk6  [PLYMesh] Loading mesh from "mitsuba.ply" ..
2023-01-15 14:19:56 DEBUG wrk6  [PLYMesh] "mitsuba.ply": read 49533654 faces, 24811372 vertices (1.29 GiB in 1.71s)
2023-01-15 14:20:19 INFO  main  [Scene] Embree ready. (took 22.9s)
2023-01-15 14:20:19 INFO  main  [xml.cpp:1451] Done loading XML file "test.xml" (took 29.673s).
2023-01-15 14:20:19 INFO  main  [SamplingIntegrator] Starting render job (750x500, 25 samples, 20 threads)
Rendering [==============================================================================================================================================================================================================================] (16.1s, ETA: 0ms)
2023-01-15 14:20:35 INFO  main  [SamplingIntegrator] Rendering finished. (took 16.122s)
2023-01-15 14:20:35 INFO  main  [HDRFilm] ✔  Developing "test.exr" ..
2023-01-15 14:20:35 DEBUG main  [Bitmap] Writing OpenEXR file "test.exr" (750x500, rgb, float16) ..

The log output using mitsuba 2 is significantly greater:

2023-01-15 14:34:57 INFO  main  [mitsuba.cpp:218] Mitsuba version 2.2.1 (master[4e7628c6], Mac OS, 64bit, 20 threads, 4-wide SIMD)
2023-01-15 14:34:57 INFO  main  [mitsuba.cpp:219] Copyright 2020, Realistic Graphics Lab, EPFL
2023-01-15 14:34:57 INFO  main  [mitsuba.cpp:220] Enabled processor features: sse4.2 x86_64
2023-01-15 14:34:57 INFO  main  [xml.cpp:1221] Loading XML file "test.xml" ..
2023-01-15 14:34:57 INFO  main  [xml.cpp:1222] Using variant "scalar_rgb"
2023-01-15 14:34:57 INFO  main  [xml.cpp:355] "test.xml": in-memory version upgrade (v2.0.0 -> v2.2.1) ..
2023-01-15 14:34:57 INFO  main  [xml.cpp:660] Loading included XML file "/Users/rrothenb/dev/mitsuba3/sensor.xml" ..
2023-01-15 14:34:57 INFO  main  [xml.cpp:355] "/Users/rrothenb/dev/mitsuba3/sensor.xml": in-memory version upgrade (v2.0.0 -> v2.2.1) ..
2023-01-15 14:34:57 INFO  main  [PluginManager] Loading plugin "plugins/srgb.dylib" ..
2023-01-15 14:34:57 INFO  main  [PluginManager] Loading plugin "plugins/multijitter.dylib" ..
2023-01-15 14:34:57 INFO  tbb00 [PluginManager] Loading plugin "plugins/volpathmis.dylib" ..
2023-01-15 14:34:57 INFO  tbb01 [PluginManager] Loading plugin "plugins/envmap.dylib" ..
2023-01-15 14:34:57 INFO  tbb02 [PluginManager] Loading plugin "plugins/lanczos.dylib" ..
2023-01-15 14:34:57 DEBUG tbb01 [Bitmap] Loading RGBE file "/Users/rrothenb/dev/mitsuba3/mitsuba.rgbe" (7071x7071, rgb, float32) ..
2023-01-15 14:34:57 INFO  tbb03 [PluginManager] Loading plugin "plugins/hg.dylib" ..
2023-01-15 14:34:57 INFO  tbb04 [PluginManager] Loading plugin "plugins/roughplastic.dylib" ..
2023-01-15 14:34:57 INFO  tbb08 [PluginManager] Loading plugin "plugins/roughconductor.dylib" ..
2023-01-15 14:34:57 INFO  tbb07 [PluginManager] Loading plugin "plugins/bitmap.dylib" ..
2023-01-15 14:34:57 DEBUG tbb07 [BitmapTexture] Loading bitmap texture from "mitsuba.blend.rgbe" ..
2023-01-15 14:34:57 INFO  tbb02 [PluginManager] Loading plugin "plugins/hdrfilm.dylib" ..
2023-01-15 14:34:57 DEBUG tbb07 [Bitmap] Loading RGBE file "/Users/rrothenb/dev/mitsuba3/mitsuba.blend.rgbe" (11726x9937, rgb, float32) ..
2023-01-15 14:34:57 INFO  tbb03 [PluginManager] Loading plugin "plugins/homogeneous.dylib" ..
2023-01-15 14:34:57 INFO  tbb09 [PluginManager] Loading plugin "plugins/uniform.dylib" ..
2023-01-15 14:34:57 INFO  tbb09 [PluginManager] Loading plugin "plugins/twosided.dylib" ..
2023-01-15 14:34:57 INFO  tbb03 [PluginManager] Loading plugin "plugins/constvolume.dylib" ..
2023-01-15 14:34:57 INFO  main  [PluginManager] Loading plugin "plugins/thinlens.dylib" ..
2023-01-15 14:34:57 INFO  tbb04 [PluginManager] Loading plugin "plugins/blendbsdf.dylib" ..
2023-01-15 14:35:02 INFO  tbb04 [PluginManager] Loading plugin "plugins/ply.dylib" ..
2023-01-15 14:35:02 DEBUG tbb04 [PLYMesh] Loading mesh from "mitsuba.ply" ..
2023-01-15 14:35:03 DEBUG tbb04 [PLYMesh] "mitsuba.ply": read 49533654 faces, 24811372 vertices (1.29 GiB in 1.43s)
2023-01-15 14:35:03 INFO  main  [ShapeKDTree] Building a SAH kd-tree (49533654 primitives) ..
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree] kd-tree configuration:
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree]    Cost model               : SurfaceAreaHeuristic3[
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree]                                 query_cost = 20,
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree]                                 traversal_cost = 15,
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree]                                 empty_space_bonus = 0.9
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree]                               ]
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree]    Max. tree depth          : 40
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree]    Scene bounding box (min) : [0.137224, -1.00262, -1.03862]
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree]    Scene bounding box (max) : [1.09679, 0.360965, -6.63687e-17]
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree]    Min-max bins             : 128
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree]    O(n log n) method        : use for <= 65536 primitives
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree]    Stopping primitive count : 3
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree]    Perfect splits           : yes
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree]    Retract bad splits       : yes
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree]
2023-01-15 14:35:03 DEBUG main  [TShapeKDTree] Creating a preliminary index list (189 MiB)
2023-01-15 14:36:12 DEBUG main  [TShapeKDTree] Structural kd-tree statistics:
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    Primitive references        : 390722866 (1.46 GiB)
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    kd-tree nodes               : 420943325 (3.14 GiB)
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    kd-tree depth               : 40
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    Temporary storage used      : 636 MiB
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    Parallel work units         : 2625
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    Leaf node histogram         : 0(108359335) 1(3413102) 2(26267621) 3(29587072)
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]                                  4(9719804) 5(3692315) 6(24285100) 7(2275416)
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]                                  8(1413813) 9(501896) 10(398748) 11(177755)
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]                                  12(165958) 13(61575) 14(56464) 15(24575)
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree] Qualitative kd-tree statistics:
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    Retracted splits            : 0
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    Bad refines                 : 0
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    Pruned                      : 170174
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    Largest leaf node           : 62 primitives
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    Avg. prims/nonempty leaf    : 3.83
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    Expected traversals/query   : 173.43
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    Expected leaf visits/query  : 46.20
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    Expected prim. visits/query : 35.61
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]    Final cost                  : 2369.42
2023-01-15 14:36:20 DEBUG main  [TShapeKDTree]
2023-01-15 14:36:20 INFO  main  [ShapeKDTree] Finished. (4.59 GiB of storage, took 1.27m)
2023-01-15 14:36:20 INFO  main  [SamplingIntegrator] Starting render job (750x500, 25 samples, 20 threads)
Rendering [==============================================================================================================================================================================================================================] (45.5s, ETA: 0ms)
2023-01-15 14:37:05 INFO  main  [SamplingIntegrator] Rendering finished. (took 45.528s)
2023-01-15 14:37:05 INFO  main  [HDRFilm] ✔  Developing "test.exr" ..
2023-01-15 14:37:05 DEBUG main  [Bitmap] Writing OpenEXR file "test.exr" (750x500, rgba, float16) ..
2023-01-15 14:37:06 INFO  main  [Profiler] Recorded 95514 samples, used 16/256 hash table entries.
2023-01-15 14:37:06 INFO  main  [Profiler] ⏱  Profile (hierarchical):
2023-01-15 14:37:06 INFO  main  [Profiler]     Idle                                              1.90%
2023-01-15 14:37:06 INFO  main  [Profiler]     Integrator::render()                              34.94%
2023-01-15 14:37:06 INFO  main  [Profiler]       Endpoint::sample_ray()                          0.14%
2023-01-15 14:37:06 INFO  main  [Profiler]       ImageBlock::put()                               0.15%
2023-01-15 14:37:06 INFO  main  [Profiler]       SamplingIntegrator::sample()                    34.35%
2023-01-15 14:37:06 INFO  main  [Profiler]         BSDF::eval(), pdf()                           3.07%
2023-01-15 14:37:06 INFO  main  [Profiler]           BSDF::sample()                              0.23%
2023-01-15 14:37:06 INFO  main  [Profiler]           Texture::eval()                             0.86%
2023-01-15 14:37:06 INFO  main  [Profiler]         BSDF::sample()                                0.41%
2023-01-15 14:37:06 INFO  main  [Profiler]           Texture::eval()                             0.03%
2023-01-15 14:37:06 INFO  main  [Profiler]         Endpoint::eval(), pdf()                       0.39%
2023-01-15 14:37:06 INFO  main  [Profiler]         Scene::ray_intersect()                        26.41%
2023-01-15 14:37:06 INFO  main  [Profiler]           KDTree::create_surface_interaction()        0.83%
2023-01-15 14:37:06 INFO  main  [Profiler]         Scene::sample_emitter_direction()             2.61%
2023-01-15 14:37:06 INFO  main  [Profiler]           Endpoint::sample_direction()                2.55%
2023-01-15 14:37:06 INFO  main  [Profiler]     Scene initialization                              63.17%
2023-01-15 14:37:06 INFO  main  [Profiler] ⏱  Profile (flat):
2023-01-15 14:37:06 INFO  main  [Profiler]     Scene initialization                              63.17%
2023-01-15 14:37:06 INFO  main  [Profiler]     Scene::ray_intersect()                            25.58%
2023-01-15 14:37:06 INFO  main  [Profiler]     Endpoint::sample_direction()                      2.55%
2023-01-15 14:37:06 INFO  main  [Profiler]     BSDF::eval(), pdf()                               1.99%
2023-01-15 14:37:06 INFO  main  [Profiler]     Idle                                              1.90%
2023-01-15 14:37:06 INFO  main  [Profiler]     SamplingIntegrator::sample()                      1.46%
2023-01-15 14:37:06 INFO  main  [Profiler]     Texture::eval()                                   0.88%
2023-01-15 14:37:06 INFO  main  [Profiler]     KDTree::create_surface_interaction()              0.83%
2023-01-15 14:37:06 INFO  main  [Profiler]     BSDF::sample()                                    0.61%
2023-01-15 14:37:06 INFO  main  [Profiler]     Endpoint::eval(), pdf()                           0.39%
2023-01-15 14:37:06 INFO  main  [Profiler]     Integrator::render()                              0.29%
2023-01-15 14:37:06 INFO  main  [Profiler]     ImageBlock::put()                                 0.15%
2023-01-15 14:37:06 INFO  main  [Profiler]     Endpoint::sample_ray()                            0.14%
2023-01-15 14:37:06 INFO  main  [Profiler]     Scene::sample_emitter_direction()                 0.07%

Any ideas of what I can try?

[wjakob]

You can specify -v to get more debug output. The KD-tree log messages aren't there anymore because the default is now to use the Embree ray intersector. The builtin profiler was removed since it wasn't that useful (better to use VTune, or a device-specific profiler like NVIDIA NSight).

[rrothenb]

I've been overcompensating by using -vvvvv, and that's what I get.

Should there be more log output? It takes time to render which makes me think it's working, but the generated exr is always black.

[rrothenb]

My scene:

<scene version="2.0.0">
    <sensor type="thinlens" id="Camera-camera">
        <string name="fov_axis" value="larger"/>
        <float name="focus_distance" value=".25"/>
        <float name="aperture_radius" value="0.0009917138274017992"/>
        <float name="fov" value="51.86537651130504"/>
        <transform name="to_world">
            <lookat origin="0, 0, -0.8585983210409114" target="0.5469308208998077, -0.26214922522936907, -0.7950751290673757" up="0, 0, 1"/>
        </transform>

        <sampler type="multijitter">
            <integer name="sample_count" value="25"/>
        </sampler>

        <film type="hdrfilm" id="film">
            <integer name="width" value="750"/>
            <integer name="height" value="500"/>
            <rfilter type="lanczos"/>
        </film>
    </sensor>
    <emitter type="envmap" id="Area_002-light">
        <string name="filename" value="mitsuba.rgbe"/>
        <float name="scale" value="1"/>
        <transform name="to_world">
            <rotate value="1, 0, 0" angle="42.52153148307115"/>
            <rotate value="0, 1, 0" angle="174.78920483590517"/>
            <rotate value="0, 0, 1" angle="-89.96798023381373"/>
        </transform>
    </emitter>
        <integrator type="volpathmis">
            <integer name="max_depth" value="16"/>
        </integrator>
    <medium id="medium1" type="homogeneous">
        <float name="scale" value="174.97668318898894"/>
        <rgb name="albedo" value="0.8865052266813684, 0.7570513720966109, 0.42663476277231915"/>
        <rgb name="sigma_t" value="0.621490089951632, 0.9016037657403224, 0.8704755626774794"/>
        <phase type="hg">
                        <float name="g" value="-0.04416090689467579"/>
                </phase>
    </medium>
   <shape type="ply">
        <string name="filename" value="mitsuba.ply"/>
        <ref id="medium1" name="interior"/>
        <bsdf type="blendbsdf">
                        <texture type="bitmap" name="weight">
                                <string name="filename" value="mitsuba.blend.rgbe"/>
                        </texture>
                        <bsdf type="blendbsdf">
                                <float name="weight" value="0"/>
                                      <bsdf type="twosided">
                                                <bsdf type="roughplastic">
                                        <float name="alpha" value="0.9513778149097305"/>
                                        <float name="int_ior" value="1.328977962627887"/>
                                                        <rgb name="diffuse_reflectance" value="0.8865052266813684, 0.7570513720966109, 0.42663476277231915"/>
                                                </bsdf>
                                     </bsdf>
                                   <bsdf type="twosided">
                                                <bsdf type="roughconductor">
                                                <float name="alpha" value="0.9513778149097305"/>
                                                <rgb name="eta" value="0.8865052266813684, 0.7570513720966109, 0.42663476277231915"/>
                                                <rgb name="k" value="0.621490089951632, 0.9016037657403224, 0.8704755626774794"/>
                                                </bsdf>
                                        </bsdf>
                        </bsdf>
                        <bsdf type="blendbsdf">
                                <float name="weight" value="0"/>
                                      <bsdf type="twosided">
                                                <bsdf type="roughplastic">
                                        <float name="alpha" value="0.00032968390778173113"/>
                                        <float name="int_ior" value="1.328977962627887"/>
                                                        <rgb name="diffuse_reflectance" value="0.621490089951632, 0.9016037657403224, 0.8704755626774794"/>
                                                </bsdf>
                                     </bsdf>
                                   <bsdf type="twosided">
                                                <bsdf type="roughconductor">
                                                <float name="alpha" value="0.00032968390778173113"/>
                                                <rgb name="eta" value="0.621490089951632, 0.9016037657403224, 0.8704755626774794"/>
                                                <rgb name="k" value="0.8865052266813684, 0.7570513720966109, 0.42663476277231915"/>
                                                </bsdf>
                                        </bsdf>
                        </bsdf>
                </bsdf>
    </shape>
</scene>

[rrothenb]

Though that's a red herring. The fact is that I get the same results with tutorials/scenes/cbox.xml

[rrothenb]

Interestingly enough, if I build it using the kd-tree (-DMI_ENABLE_EMBREE=0) it still comes out black.