Materials Type Validation

>>> [ERROR] Character materials type check - FAIL.
> Material "body_mtl" is of type "lambert" which is not supported.
> Please make sure that all geometries have the correct materials assigned.
Currently only "standardSurface", "aiStandardSurface" and "aiFlat"shader types are supported for rendering meshes.
Please make sure to use only those materials.
For more information, please visit the following page: Shading