[eferg]

I have made a flat plane as a floor for my main object to sit on. I want the foreground of the floor to be reflective, and the background to be diffuse. This is because I want the main object to have a ground reflection, yet I don't want the bright reflections from the HDR now hitting the floor to show behind the object.

From what I have read, it appears I can create a material with a reflection layer and a diffuse layer, and use a B&W gradient map to blend the two layers. I'm very new to Maxwell and would appreciate any detailed help in how to do this. Assuming this is possible, what size should the B&W gradient image be? How do I build this material?

Regards,
Ed

[jfrancis]

You can also build a ramp directly into the roughness so that a single layer becomes more diffuse, rather than blending between two layers and having the 'cross fade'

http://www.youtube.com/watch?v=dB7eNbdQvqU

[eferg]

Thank you - that looks like a great solution and I will experiment with a gray scale radial gradient roughness map so my main object has a reflection in the metal floor directly underneath, while the rest of the floor will not show strong HDR reflections.

Is there a recommended size for such a map?

Ed

[jfrancis]

Is there a recommended size for such a map?

Ed

From what you describe I'd try something quite low in resolution, single channel gray tiff with dot gain color management off.

If you don't want total shininess then don't let your image go all the way down to black, and if you don't want total lambert diffuseness then don't let your image make it all the way up to 100% white.

And on top of that you have the roughness slider. Whatever that is set to will modulate (multiply itself by) the normalized (0..1 space) texture grays.

[eferg]

Thank you again for the very clear explanation!

[Fernando Tella]

Just remember:
black = 0 = polished
white = 100 = diffuse

If you have a map at roughness slot the roughness number still matters. For example, if you set roughness to 80 then black = 0 and white = 80 and the shades of grey are interpolated between those values instead of 0-100

[eferg]

I tried out a roughness map on my large ground plane and it works better than expected. The background is nicely diffused and the area under my main object shows a soft reflection. One of the keys to making the roughness blend well was to change the contrast on the map within Maxwell. Using this technique was easier than playing with the HDR to get the right mix of soft background lighting and foreground reflections.

Ed