ARKit face tracking PBR

Question

I am usig the ARKit face tracking configuration and displaying the face mesh in realtime, i can successfully add diffuse and normal maps to it, and they display correctly, but no luck with roughness or metalness, roughness has no effect and metalness is rendering all black and dull/opaque, things i have tried:

• self.contentNode?.geometry?.firstMaterial?.roughness.contents = UIColor.black //UIColor.white
• self.contentNode?.geometry?.firstMaterial?.metalness.contents = UIColor.black //UIColor.white
• self.contentNode?.geometry?.firstMaterial?.roughness.contents = myMetallnessTextureImage
• self.contentNode?.geometry?.firstMaterial?.metalness.contents = myRoughnessTextureImage

It is worth noting that most of the light management is done by the session, thats why the mesh responds to the ambient and direct light when using it, and when there is only ambient light, the mesh looks di-electric/rough, and when there is a strong directional light it looks metallic/smooth, is it the session taking control of these params?

If i export the face mesh as an .obj, when opening it on Xcode i can tweak the material properties, and i can get a fully metallic shiny face, but when applying the same params to my mesh in realtime they do not work.

In the end, what i want is to be able to have some part of the face metallic by using a grayscale map.

Also i am aware that the face tracking config does not allow an environment map(correct me if wrong) so a fully mirror like texture will look quite un-realistic but anyway, it should work.

Thanks!

Answer 1

Solved, i was missing this parameter in my setup method:

sceneView.autoenablesDefaultLighting = true

This adds what seems to be an ambient light to the mesh reflections, and roughness and metalness are taking effect.