In Unreal Engine 5.6, when in Path Tracer rendering mode, scaling the character up or down affects the hair rendering. How can this problem be fixed?
Hello there @WG_XU!
Indeed, the groom asset can get a bit wacky in combination with path tracer. Checking around the community, there a few ways to deal with this effect. The simplest method would be to send your asset to Blender, scale the source mesh and the groom, apply transforms, and send it back, thus keeping the scale at 1 in UE.
If this is not an option, you can play around with groom parameters to compensate. Open your groom asset, and adjust the scale and width parameters to reduce the spike effect (although it won’t be a perfect fix at all camera angles).
Another alternative, is to change your groom strands to cards. Since cards behave has geo, they should react correctly to scale changes under path tracer. You can check all details on this process with the following doc:
If the issue persists, there are a few manual command lines to test, that affect strands’ behaviour in engine, you can check in the community tutorial below: