how to render a face with diffuse_uv_map, specular_uv_map and roughness_uv_map?

[anewusername77]

Thanks.

[Speierers]

@anewusername77 please take the time to better describe what it is you are trying to achieve, what you have already tried, what failed and what succeeded. Then we will be able to answer your questions.

[njroussel]

What is your exact issue?
The specular and spec_tint parameter should be what you are looking for. The two papers that are referenced in the documentation of the principled BSDF might also be helpful to you to understand the model.

[anewusername77]

What is your exact issue? The specular and spec_tint parameter should be what you are looking for. The two papers that are referenced in the documentation of the principled BSDF might also be helpful to you to understand the model.

hi njroussel,
I managed to solve it! by using mi.traverse()to change params['vertex_texcoords'] with the help of this doc: https://mitsuba.readthedocs.io/en/stable/src/api_reference.html#mitsuba.Mesh.vertex_texcoord

by the way, is it possible to update this method to use a texture for specular instead of a simple float?
---------- previous reply----------------
my issue is I want to load a uv diffuse texture picture for base_color, using bitmap , to render a face mesh. But the uv texture seems doesn't match to mesh. I noticed has_vertex_texcoords in mi.mesh, but how can i add vertex_texcoords to it ? with add_attribute? or is there any other way to match uvtexture in bsdf to mesh?

uv texture is like:

[anewusername77]

Any updates? I'm facing the same issue with using a specular map with principled BSDF

just use diffuse tex in base_color, and specular with a simple float

[giuvecchio]

My issue is with a bitmap specular map. Loading it into the specular_tint parameter doesn't seem to affect the rendering,

These are the maps used. What should the correct way be to use those?

[anewusername77]

My issue is with a bitmap specular map. Loading it into the specular_tint parameter doesn't seem to affect the rendering,

These are the maps used. What should the correct way be to use those?

yes my specular map was also a texture, but I don't think inprincipled bsdf specular can be a texture....so I just change it to a float

[NMontanaBrown]

Hiya, I have encountered the same issue and managed to resolve it the following way.

I have a .ply mesh with ST coordinates and it's corresponding baked diffuse map from Blender. Checking the scene parameters through params['vertex_texcoords'] as suggested above seems to return the same coords as in the .ply file.

The renderer expects UV coordinates though, so for conversion to UV:

`python

tex = params["PLYMesh.vertex_texcoords"]

new_tex = []
for i, item in enumerate(tex):
if (i%2)==0:
new_tex.append(item)
else:
new_tex.append(1-item)

params.update()`

The above applies the conversion u=s v=1-t.

I get the following renders with and without applying this change. Hope this helps anyone that comes across this!