Does adding a second diffuse layer do anything?

[Jackson_cg]

I still haven't got my head round the Service Releases' method of working with materials (I always used VRay Linked Materials with v.1.00), but there's one thing that still baffles me. Does adding a second diffuse layer in the VfSU material editor actually do anything? I'm trying to add a very large scale noise map to a very small scale tarmac texture (so it looks a bit more procedural from a distance), but I can't see any difference in the render.

I originally tried to do it by making the existing diffuse map a blend of the SU diffuse Acolour and a second blend of the SU diffuse texture and a noise map. Trouble is since installing v.1.05.02, VfSU sometimes loses it's link to the SU diffuse Acolour so although a material might be displayed almost black in SU it renders in VfSU as the same shade as the original texture image map, light grey. That's why I've been trying to add a second diffuse layer instead.

Thanks in advance,
Jackson

[thomthom]

Re: Does adding a second diffuse layer do anything?

You need the original diffuse layer to maintain the texture mapping. If you replace it with something else it'll disappear.

There are however cases where you need mapping, but don't need a texture for the diffuse. You'll still need to apply a texture to the diffuse.

Say you want to make a reflection pattern to a material. A shiny logo. I'd use the opacity map in the diffuse. Then set it's opacity to fully transparent. I then create a new diffuse layer and this is the one that'll be rendered. Now I have texture mapping co-ordinates and I can add the opacity map to my reflection layer.
The drawback here is that the object turns out transparent in SU. You'll have to turn of transparency in the SU viewport. Alternatively, after mapping, you can replace the diffuse texture with a texture in the colour you want your diffuse to be. But make sure it has the same proportions as the one you replace or you will mess up the mapping you've done.

I also use multiple diffuse layers when I create dirty materials. I have a normal diffuse, then a rust, them maybe some dents, to each which I apply opacity maps so I get the blend I want.

[thomthom]

Re: Does adding a second diffuse layer do anything?

Just thinking, the easier answer is: additional diffuse layers only have a purpose if the previous layers is transparent. It works just like Layers and Layer Masks in Photoshop.

[Jackson_cg]

Re: Does adding a second diffuse layer do anything?

Thanks Thom!

I started reading your first reply, got a bit confused, wondered why you were talking about reflection patterns, but then your secnd post made all perfectly clear! Just did a quick test, added noise transparency map to diffuse layer 1 and low and behold diffuse layer showed through perfectly! This is going to be sooooo useful, tusen takk!

[thomthom]

Re: Does adding a second diffuse layer do anything?

Thanks Thom!

I started reading your first reply, got a bit confused, wondered why you were talking about reflection patterns, but then your secnd post made all perfectly clear! Just did a quick test, added noise transparency map to diffuse layer 1 and low and behold diffuse layer showed through perfectly! This is going to be sooooo useful, tusen takk!

Scandinavian?!?



I keep catching myself in describing things where it initially makes sense in my head, but when I re-read it I don't get it myself. I try to discipline myself to re-read before I post.


I was actually going to do a post about multiple diffuse layers in the tips and tricks section. Got any suggestions to what might be interesting to demonstrate?

[Jackson_cg]

Re: Does adding a second diffuse layer do anything?

Scots, but live in Sweden. ;D

Yeah, it's always a problem discussing render progs online e.g. if you were using a scan of a road map (as in an actual paper map (karta) for finding your way around) as a diffuse texture and it's UV ratio was rendering wrong, the topic title would be "Map map maps incorrectly" LOL. Language disguises thought.

Re: diffuse layers tips, I've been racking my brain to try to work out how to get SU/VfSU to map dirt maps onto roads that actually approximate the darker lines of the road where traffic drives and towards the gutters where dirt tends to accumulate. The best way I can think of at the moment would be:
1) take an aerial non-perspective view of the road layout from SU
2) open it in Photoshop
3) create a new layer and paint the dirt map using the aerial view as a template and save.
4) load that image as the texture map in SU, use texture position to reposition and scale it so it aligns exactly with the road edges (to get exact UV mapping).
5) create a second diffuse layer of detailed tarmac material.
6) create a second diffuse layer of much darker detailed tarmac material.
7) add a 100% transparency layer to the first diffuse layer (so we don't actually see the dirt map, but maintain it's UV mapping) and it still displays in SU.
apply the saved PS dirt map as a transparency map on the second diffuse layer allowing the third diffuse layer to show through as darker patches and tracks on the road.

Obviously the PS work is unavoidable, but I'd love to know if there was a way to just use a standard detailed tarmac material in SU (so it would display correctly) and apply the dirt transparency in VfSU to the exact scale and position of the road layout. Maybe I can use SU's texture position editor to see how many times the texture tiles across the model in SU, then scale up the dirt map in VfSU by that number?

Jeez, now I think I need a lie down!

[dalomar_cg]

Re: Does adding a second diffuse layer do anything?

All the layers (emitters, reflection, diffuse or refraction) are all, what I like to call, Self-Shadowing. Basically, that means that in order for any light to reach a bottom layer, there has to be some level of transparency of the layers above it.

In terms of diffuse (and emitters too), this concept is rather simple because its very explicit how those particular layers deal with transparency. So, if you have two diffuse layers, the bottom one won't matter unless the top one has some degree of transparency. Logos are a good way to use this layer system to your advantage, although doing a logo on top of another texture is pretty tough (to get the mapping for both right).

For reflection, the transparency is a little anti-intuitive. Basically, whatever you're using as your reflection value (whether its just a color, or Fresnel, or a map) will actually be your transparency value. The explanation beyond that gets a little more complicated.

For refraction, transparency's almost never used, but is kind of confusing because the object "looks" transparent. Refraction is a material quality just like any other, so when it does any refraction stuff, its not taking any transparency into account. The only real instance that I can think of using transparency within refraction is to make a dispersive material, but that's a whole other post.

[thomthom]

Re: Does adding a second diffuse layer do anything?

For reflection, the transparency is a little anti-intuitive. Basically, whatever you're using as your reflection value (whether its just a colour, or Fresnel, or a map) will actually be your transparency value. The explanation beyond that gets a little more complicated.

In Micha's tutorial about materials, it describes two reflection layers, frist one that's not very glossy, then another one underneath that's much more glossy. From what I could gather from the article, both layers had the same fresnel IOR. Which I thought was odd as I'd expected the first reflection layer to completely block out the second since they both had the same settings except the glossiness. Or is there something to the way that the light scatter?

[dalomar_cg]

Re: Does adding a second diffuse layer do anything?

Within SU, the key to any mapping work while working with multiple diffuse layers/maps, is to make sure that the maps require the same texture position in order to line up. In most other 3d apps, there is the context of multiple coordinate spaces for textures. This allows for multiple maps to be adjusted separately from each other. SU does not have this capabilty, so anything that you map will have to be done with one coordinate system.

Maybe this doesn't make sense to you guys, but its a huge difference and significantly limiting when it comes to mapping multiple textures.

From the sounds of your process, you've got everything structured to work off of the same coordinates.

[dalomar_cg]

Re: Does adding a second diffuse layer do anything?

In Micha's tutorial about materials, it describes two reflection layers, frist one that's not very glossy, then another one underneath that's much more glossy. From what I could gather from the article, both layers had the same fresnel IOR. Which I thought was odd as I'd expected the first reflection layer to completely block out the second since they both had the same settings except the glossiness. Or is there something to the way that the light scatter?

All the fresnel map really does is create a transparency layer by which to blend the amount of reflections. Essentially, regardless of the transparency of a given reflection, the reflection still has to be traced regardless. Therefore, we're always calculating reflections as if they're a perfect mirror, but we just blend them for the final result that we're looking for. For a good example of this add the Raw Reflection and the Reflection Filter channel to your rendering and look at the result. The Raw Reflection filter will always have everything look like a mirror, and the reflection filter is the "transparency" for that perfect reflection. (if you're doing the math with compositing... Raw Reflection * Reflection Filter will give you the Reflection channel)

This isn't always 100% true because reflection glossiness does have an affect on the transparency of your reflection. Essentially the more glossy an object is, the more the materials underneath tend to show through. Most of the time, this isn't really that significant, so I wouldn't really worry about glossiness affecting the transparency of your layer too much.

[thomthom]

Re: Does adding a second diffuse layer do anything?

Within SU, the key to any mapping work while working with multiple diffuse layers/maps, is to make sure that the maps require the same texture position in order to line up. In most other 3d apps, there is the context of multiple coordinate spaces for textures. This allows for multiple maps to be adjusted separately from each other. SU does not have this capabilty, so anything that you map will have to be done with one coordinate system.

Maybe this doesn't make sense to you guys, but its a huge difference and significantly limiting when it comes to mapping multiple textures.

From the sounds of your process, you've got everything structured to work off of the same coordinates.

Yea, that's what I've been doing. Keeping textures lining up and keeping them with the same proportions. I some times create a dummy texture with guide lines which I use in the diffuse to create the mappings. At school I used 3DSMax so I'm used to having multiple UV maps, but at the office where I work now we only use SU.

[thomthom]

Re: Does adding a second diffuse layer do anything?

In Micha's tutorial about materials, it describes two reflection layers, frist one that's not very glossy, then another one underneath that's much more glossy. From what I could gather from the article, both layers had the same fresnel IOR. Which I thought was odd as I'd expected the first reflection layer to completely block out the second since they both had the same settings except the glossiness. Or is there something to the way that the light scatter?

All the fresnel map really does is create a transparency layer by which to blend the amount of reflections. Essentially, regardless of the transparency of a given reflection, the reflection still has to be traced regardless. Therefore, we're always calculating reflections as if they're a perfect mirror, but we just blend them for the final result that we're looking for. For a good example of this add the Raw Reflection and the Reflection Filter channel to your rendering and look at the result. The Raw Reflection filter will always have everything look like a mirror, and the reflection filter is the "transparency" for that perfect reflection. (if you're doing the math with compositing... Raw Reflection * Reflection Filter will give you the Reflection channel)

This isn't always 100% true because reflection glossiness does have an affect on the transparency of your reflection. Essentially the more glossy an object is, the more the materials underneath tend to show through. Most of the time, this isn't really that significant, so I wouldn't really worry about glossiness affecting the transparency of your layer too much.

Sorry, I was confusing names. Corey Rubadue wrote the tutorial. http://asgvis.com/index.php?option=c...Metal_material
Thinking of it now it makes more sense than when I first was working with it.

[dalomar_cg]

Re: Does adding a second diffuse layer do anything?

Yea, filter color is a completely different thing, and one of the most under used aspects of reflection IMHO...now that I think about it a reflection filter channel would be nice...

[Jackson_cg]

Re: Does adding a second diffuse layer do anything?

Wow, you guys are replying so fast I'm struggling to keep up. Having put Thom's advice to use and thought through the process of applying a very large dirt map to a road which I decribed above I decided to try it out for the first time. It took a little adjusting, but I'm pretty happy with the result, especially as there is absolutely no post-processing work on this, it's saved straight out of VfSU.