Thomas Martineau
Ansys Employee

Hi,

When you use an intensity sensor, it's located at the infinite, whatever the distance you see in the 3D view, except if you activate near field.

On the result, there is not enough ray per pixel, your sensor sampling is very high, you can decrease it a lot ! Else you will have to launch much more rays. 

I did a quick test and this is the result :

 

Thomas