Mesh color not displayed when loading PLY/OBJ with SAPIEN

[pioneer-innovation]

@fbxiang Hi! I have several mesh models stored in PLY and OBJ formats, with vertex colors preserved.
These models were exported from CloudCompare and MeshLab.

When I load them into SAPIEN , the geometry appears correctly, but all colors are missing — the mesh shows up in plain gray.

this is my loading code:

builder = self.sim.scene.create_actor_builder()
builder.add_visual_from_file(filename=self.scene_visual_path)
mesh = builder.build(name="mesh")
mesh.set_pose(sapien.Pose(p=[-0.2, 0, 1.0 + 0.05]))

[fbxiang]

The vertex color was intentionally not rendered to encourage the use of texture maps (they are actually loaded, just not used by the default renderer). The main concern was that different authors often have different expectations (such as color spaces) when creating vertex colors, and it is not clear how to mix vertex color with other materials in general.

The vertex color is actually accessible to the shaders by adding layout(location = 5) in vec4 color; in the vertex shader just in case someone really really want it.

SAPIEN/vulkan_shader/default/gbuffer.vert

Line 33 in fd97712

layout(location = 4) in vec3 bitangent;

[pioneer-innovation]

I use blender to set material color, it still can not show color in simulator.

[fbxiang]

The procedure you used in blender would still export to vertex color (not textures). In fact, blender may not export custom node graphs correctly (node graphs in general can only be used in blender itself).
As a possible workaround, you can try to learn about "baking vertex color as texture in blender". However, depending on the complexity of the scene, the baked result may not be good enough and you will have to write a custom shader.

[TtopsBo]

@fbxiang
Hello fbxiang,
I also encountered the color issue when loading urdf. I have colored foream.dae, but when I used urdf to load the robot, it was pure light grey. Where the problem exists? Thanks.

[fbxiang]

@fbxiang Hello fbxiang, I also encountered the color issue when loading urdf. I have colored foream.dae, but when I used urdf to load the robot, it was pure light grey. Where the problem exists? Thanks.

Just delete all the <material> tags in your URDF. We use this tag to override materials that come with the mesh.

[TtopsBo]

@fbxiang Hello fbxiang, I also encountered the color issue when loading urdf. I have colored foream.dae, but when I used urdf to load the robot, it was pure light grey. Where the problem exists? Thanks.

Just delete all the tags in your URDF. We use this tag to override materials that come with the mesh.

Well solved, thanks for your quick reply.