Robot colors are extremely muted

[QuantuMope]

Description

When running isaacsim in the terminal and loading in a URDF model, the robot's colors are extremely muted. Below you can see the isaacsim rendered robot on top and a third party render on the bottom.

Disable materials is not enabled and rendering is set to RTX - Real-Time. Tried fidgeting with tons of different settings but nothing seems to fix this.

I've also attached the URDF and texture files. Simply import piper_x_description.urdf.
piper_x.zip
Third party viewer is https://viewer.robotsfan.com/

Isaac Sim version

5.1.0

Operating System (OS)

22.04

GPU Name

RTX 4090

GPU Driver and CUDA versions

Driver 580.159.04 CUDA 13.2

Logs

No response

Additional information

No response

[vick-yu]

Hi @QuantuMope,
 
Thanks for the detailed report with the URDF and comparison images.
 

What's Happening

 
The colors in your URDF/DAE files are being imported correctly -- the diffuse color values in Isaac Sim match the source COLLADA materials exactly. The "muted" appearance is caused by how the materials are rendered, not how they're imported.
 
When Isaac Sim imports COLLADA (.dae) meshes, it converts Lambert materials to OmniPBR (physically-based) shaders. The key differences vs. a simple viewer like robotsfan.com:
 

• Shading model: Lambert/Phong (non-physical) vs OmniPBR (energy-conserving PBR)
• Roughness: N/A vs default 0.5 (matte look)
• Lighting: Simple ambient + directional vs environment dome (can be dim)
• Tone mapping: None (raw output) vs ACES/filmic (compresses highlights)
   
  The COLLADA Lambert specular=1.0 is not currently mapped to OmniPBR roughness during import, so all materials end up with the default matte finish regardless of their intended shininess.
   

Workaround

 
After importing your URDF, run this script to brighten the appearance:
 

import omni.usd
from pxr import UsdLux, UsdShade, Sdf
 
stage = omni.usd.get_context().get_stage()
 
# 1. Add a brighter dome light
dome = UsdLux.DomeLight.Define(stage, "/World/BrightDome")
dome.GetIntensityAttr().Set(1500.0)
 
# 2. Lower roughness on all OmniPBR materials for a glossier look
for prim in stage.Traverse():
if prim.GetTypeName() == "Shader":
mdl_attr = prim.GetAttribute("info:mdl:sourceAsset")
if mdl_attr and mdl_attr.Get() and "OmniPBR" in str(mdl_attr.Get()):
shader = UsdShade.Shader(prim)
roughness = shader.CreateInput(
"reflection_roughness_constant", Sdf.ValueTypeNames.Float)
roughness.Set(0.15)  # glossy plastic look

 
You can also adjust these interactively:

1. Window > Lighting -- increase the dome light intensity or add a Distant Light
2. Select any mesh > Material tab -- lower "Roughness" from 0.5 to ~0.1-0.2
3. Try switching to RTX - Interactive (Path Tracing) renderer for more natural lighting bounce