Does anyone knows why is there light under the object, I only used one light source. No sunlight.
Change to spotlight rectangular light. wouldn’t make a difference.
I also changed to other materials.
That would seem to be the light bouncing off of your shiny object on to the floor. So you could look at reducing the reflectivity of the object and/or the floor, I suppose.
Yeah, reflectivity will never be 100% - gloss yes, or nearly, but not reflectivity - try about 10% or so.
-Pascal
Also, for Raytraced and Rhino Render from v7 on the Physically Based material will be the better material to choose. The Custom material shader graph is very, very complex, resulting in slightly slower rendering.
Whenever I add a material from the library I tend to change its type to Physically Based. I believe that for Rhino 8 the render content library will be modernized.