BSDF child node for singlescatter BSSRDF

[xin-xinhanggao]

I want to render sssdragon with singlescatter plugin and singlescatter needs a BSDF child node. I set the child node like this

<subsurface type="singlescatter">
	<string name="material" value="skin2"/>
	<float name="scale" value="0.25"/>
	
	<bsdf type="dielectric">
		<spectrum name="diffuseReflectance" value="0"/>
	</bsdf>
</subsurface>

but get lots of nan value from ImageBlock

[holzschu]

I'm going to have a look at it.

[holzschu]

You can add:

 			<boolean name="fastSingleScatter" value="false"/>

if you want the (accurate, but slow) single scattering. I usually use:

		<subsurface type="singlescatter">
			<bsdf type="dielectric">
				<float name="intIOR" value="1.5"/>
				<float name="extIOR" value="1.0"/>
			</bsdf>
			<boolean name="fastSingleScatter" value="false"/>
                        ... material ... 
		</subsurface>

Fast single scatter is very approximate, as it ignores the second refraction. The NaN from ImageBlock occur approximately once every 10 000 sample in the sssDragon scene, less in other scenes. You can safely ignore them.