<scene version="0.4.0"> <integrator type="ptracer"/> <shape type="disk"> <transform name="toWorld"> <translate z="-1"/> </transform> <bsdf type="diffuse"/> <sensor type="irradiancemeter"> <sampler type="independent"> <integer name="sampleCount" value="128000"/> </sampler> <film type="mfilm"/> </sensor> </shape> <shape type="disk"> <boolean name="flipNormals" value="true"/> <bsdf type="diffuse"/> <transform name="toWorld"> <translate z="1"/> </transform> <emitter type="area"> <spectrum name="radiance" value="1"/> </emitter> </shape> </scene>