Specularity Map

[40th]

Re: Specularity Map

very nice explantion. how about falloff map do you have the same illustration?

That will be great! I don't know what it does at all. ???

[dkendig]

Re: Specularity Map

Fresnel is just a type of falloff. Check spot3d, there might be some more info there.

[40th]

Re: Specularity Map

Check spot3d, there might be some more info there.

I did, but didn't find info about the falloff map.

[mjm223]

Re: Specularity Map

Also, I have some textures that have both a specularity map and a reflectivity map. If a single texture has both of these maps, in which slots do we put each of them?

[artupato]

Re: Specularity Map

Clap clap clap.. very good explanation fernando. thanks!!

[mjm223]

Re: Specularity Map

I had a little free time to do an experiment with the specular map. I took one of the free textures from Arroway Textures that had a specularity map that was also used for a reflection map and glossiness map.

According to this post, I should just apply the specularity map to the Fresnel White slot in the Reflection menu. Here is what I got below:


This still looks too glossy for it to be a stone material.

Next, I decided to add that same specularity map to the Reflection Glossiness slot to see what happens. Now I have that same specularity map in two locations: One in the Fresnel White slot of the Reflection slot, and the other in the Reflection Glossiness slot. Here is what I got below:


This is how I think the material is supposed to look. It's not too glossy like the last scene. I believe adding the specularity map to both the Reflection and Reflection Glossiness slots is the best way to go (although this slows rendering time a bit).

I then decided, just for the heck of it, to add that specularity map to the Highlight Glossiness slot to see what happens. Now the specularity map is in three different locations. Here is what I got below:


Not much of a difference in look or rendering time.


In my opinion, if you're using an Arroway texture and you want to get the desired specular effect, apply the specularity map to both the Fresnel White slot of the Reflection slot AND to the Reflection Glossiness slot. (You can also apply it to the Highlight Glossiness slot, but it doesn't look like it changes much at this point.)

I hope this helps anyonw who still has some confusion about the specularity map.

[thomthom]

Re: Specularity Map

You might not need to add the map to the Reflection/Highlight Glossiness - you can often get away with just setting a numerical value for them.

Reflection/Highlight Glossiness is what controls how blurred a reflection is a.k.a. "glossy".


As you see in your tests - the first one, with just the map in the Fresnel slot - you get reflection in some parts of the surface. But as you also noticed - it's so clear a relfection - looks like wet floor. The Glossy property, which controls the blurriness, simulates the roughness of the material. The rougher the material the lower the glossy value should be.

Also make note that Arrayway textures gives indication of the percentage the various maps should have.
For instance this map: http://www.arroway-textures.com/en/p...ete-1/contents

diffuse 100% diffuse map
bump 5% bump map
specularity 50% specularity map
glossiness 25% << specularity map

Here you should set the multiplier for the bitmap in fresnel to 0.5
and glossyness to 0.25

though these values are guides only - but a good starting indication.

[mjm223]

Re: Specularity Map

Yeah, those percentages are very helpful, especially since those values are given in the file name so that I don't have to guess or keep referring back to the website.

In the example I gave, I had used a tile material (tile-058, I believe) that had the bump map at 5% and everything else at 100%.

I'll try tweaking the Reflection Glossiness without applying a map to see if that'll speed up rendering time, but I have to say it's pretty convenient using the map and knowing exactly what to set the multiplier to without having to do trial and error.

[mjm223]

Re: Specularity Map

You might not need to add the map to the Reflection/Highlight Glossiness - you can often get away with just setting a numerical value for them.

It just occurred to me, wouldn't setting a numerical value adjust the blurriness uniformly across the material? For instance, since I used the specularity map on those example scenes, notice on the second and third scene that some of the rocks in the tiles are glossier than others. Setting a numerical value instead of using the specularity map would make all of the tiles equally glossy or blurry.

It might not be noticable in far away shots, but it will in close-up shots.

[thomthom]

Re: Specularity Map

Yes - setting the glossiness numerically will make it uniformly glossy. But because of the specular map - making the reflection itself non-uniform - you often do not notice a uniform glossy. The areas where the glossy map is nearly black - making it very blurry - is often the same areas where the specular is also very low - making it nearly invisible. Which is why can you often cut corners - but again, it depends on the material.

[mjm223]

Re: Specularity Map

I'm still using V-Ray 1.05.30 for SketchUp 7.1, but I've been trying to get myself adjusted to the new format on V-Ray 1.48.66 (which I have for SketchUp 6 right now).

I'm still having problems with the reflection properties. Below is a sample scene of wood boards that I rendered on V-Ray 1.05.30.

For the material, I have a specularity map applied to the Fresnel White slot of the Reflection slot, and a specularity map applied to the Reflection Glossiness slot. (I also have a bump map at 30%)

This is how the material should look.

I did the exact same thing on V-Ray 1.48.66, applying the specularity maps to the same slots and leaving everything else default. This is what I got:

It's still way too glossy. Am I missing a step here? Why doesn't it look like the other one when it has the same specularity and bump maps applied to the same slots?

[thomthom]

Re: Specularity Map

I think Devin murmured something about a fresnel bug...

[mjm223]

Re: Specularity Map

I see.

Well, at least I know I'm not going out of my mind ;D

Theoretically, though, this would be the right approach to adding a specularity map to a material, right?

[thomthom]

Re: Specularity Map

Yes.

what you could try, with the Fresnel - wrap it inside a TexInvert map and then see what happens.

[fpedrogo]

Re: Specularity Map

Try by inverting the mapping on the perpendicular slot. The bug is that the mapping on the fresnel perpendicular slot seem to be inverted. Where should be the black color is the white and vice-verse.

Best