How to create 'matte', dusty looking materials

[Richard7666]

I'd like to create materials like the 'chalky' wood on the top of the cabinet, and on the squat round cement jug. Does anyone have any tips as to how to achieve that look? I've tried a very low reflectivity with a low reflective IOR but it's still not looking like this photo so any ideas as to how to go about this would be great!

Cheers

[joconnell]

If dust is just some white particles layering on the up facing surfaces of an object you could look at using a falloff map with it's direction set to the world z axis and gradually introduce a bit more white to the top facing surface while making the reflection strength a bit dimmer.

[super gnu]

if its just general dustiness a falloff map set to fresnel, with the diffuse map in the front slot and a brightened,desaturated version of the same map in the side slot will give a chalky, velvetty look

[DanielBrew]

if its just general dustiness a falloff map set to fresnel, with the diffuse map in the front slot and a brightened,desaturated version of the same map in the side slot will give a chalky, velvetty look

This is exactly how I have done it in the past. However I've started playing with the new Microfacet shader this week for fabric and rough surfaces. I'm still experimenting but try using GTR tail falloff values of 1 or below for this type of material.

[Richard7666]

if its just general dustiness a falloff map set to fresnel, with the diffuse map in the front slot and a brightened,desaturated version of the same map in the side slot will give a chalky, velvetty look

probably goes without saying, but you mean this falloff map is plugged into the Reflection slot on the Vray material right?

[joconnell]

Nope, it's in the diffuse slot. So you've got your normal looking map in the slot of the falloff map for the front facing map, then you use a colour corrected version of the same map for the edge facing map slot which is made a bit whiter and less contrasty to mimic the effect of having a layer of dust that's washing out the diffuse.

[Richard7666]

ah I see, thanks! Will give it a try

[Seraph135]

Hey guys,

This type of shader is something I'm interested in. For many years I've been using this same approach with the falloff in the diffuse and it basically does what it needs to do most of the time. But I can't help but feel this really isn't physically "correct". In real life the diffuse color of an object is actually changing based on what angle I'm viewing it from. I'm curious if anyone knows a bit more about what is really happening on the surface of dusty/chalky objects like this? What is it that we are actually trying to simulate in our shaders? I'm assuming its truly just small particulate or microfacets on the surface. But is the dusty look caused by light bouncing around off all those tiny bits? Is it that the particulate is somewhat translucent? reflective? Maybe a combination of all of those?

In the vray manual the "Roughness" parameter says it can be used to create this effect. However, I'd like to know more about what this parameter is actually doing. I've had pretty limited success using it to create something that looks dusty or chalky.
http://docs.chaosgroup.com/display/VRAY3/VRayMtl

Does anyone have a better solution than the diffuse/falloff approach?

Tim J

[vlado]

The GGX BRDF might also be helpful, especially with low glossiness and low highlight tail falloff.

Best regards,
Vlado

[Deflaminis]

Would it be totally unreasonable to have a blend material with the top layer as dust?

[DanielBrew]

The GGX BRDF might also be helpful, especially with low glossiness and low highlight tail falloff.

I've been trying to use GGX since reading this thread http://forums.chaosgroup.com/showthr...GGX)-mode-help
Some of these are a bit overdone for demonstration purposes but you get the idea. None of these materials use falloff maps whereas previously I think it would be difficult to get this sort of look without.

[anchovy]

Dan would you be willing to archive a file? I would be nice id we could see your settings.

Thanks!

-Michael

[Seraph135]

Hey Dan,

How much of that look is coming from the totally white environment? Can you do a render of one of those examples with just a single vray area light somewhere up above against a black environment?

Tim J

[DanielBrew]

How much of that look is coming from the totally white environment? Can you do a render of one of those examples with just a single vray area light somewhere up above against a black environment?

Ok, here they are lit from above as you suggested.

[DanielBrew]

Dan would you be willing to archive a file? I would be nice id we could see your settings.

Thanks!

-Michael

Here's the file. As I said, I put these together very quickly yesterday morning so I'm sure they need some work before they would work in a scene.

GGX Test.zip