ray cast only mode in UniformGridRepresentation volume rendering have low quality compare to GPU based mode

ParaView Support
1

I’m using ParaView 5.13.1 on windows(local) to volume render a volume data(from a CT scan).
Found that the image quality is very low in ray cast only mode(CPU only) compare to GPU based mode.

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image1514×832 114 KB

image
image1523×842 127 KB

When enable ray tracing(OSPRay raycaster), the result is fine.

Have tried set preview resolution(View->Preview->3840*2160).
Have tried adjust level of detail(LOD) in interactive rendering options.

Is this a bug?