Gettiing the realistic material right for vray rendering

[sparksue]

Hi there,

 

I notice that to create a realistic scene, we need to tweak the material map.

(This include woods, glass, metal, etc)

 

Which are the Maps that we need to look into at?

 

1. Diffuse (actual material picture)

2. HGlossiness (Back / White Material picture)

3. RGlossiness (Back / White Material picture)

4. Bump (Back / White Material picture)

 

Is there anything else that i need to take note of?

 

P.S: I thought of creating BW Material picture (Same brightness/darkness) for HG, RG and Bump Maps. Do you think is it right to this way? Or should I create different shades of BW for all 3 maps?

 

Appreciate someone can advice on this. Thanks!

[CliveG]

As you've had no replies I'll offer my limited advice.

 

You've asked a very broad question, for which there is no single answer, which may be why it's a slow response.

 

There is no absolute formula to "tweaking" the material settings and maps, it will probably be a bit different for every material in every different scene. Unfortunately a lot will just come down to experience and trying your adjustments out. You're obviously on the right track, but whether you have different shades of B&W for your texture maps will depend on how much bump / glossiness / reflection you want for your scene.

 

Of course you can get a very good start from the many tutorials out there, I recently went through the material tutorials from Viscorbel and found them to be a really good resource for me, but that's just me, there's a lot of choice because it's a big subject.

 

If you have specific problems with a specific material - post a question here and you're sure to get some great advice.

 

Good luck

[sparksue]

Thanks for the advice. Now went to the site that you mention and notice the usage of the material creation. Look very interesting to me. Did you purchase the guide? Seem interesting to me as well.

[CliveG]

Yes I purchased the Material Tutorials and felt they were very useful for me. Plus I can (and do) always refer back to them at a later date with particular material problems to fix. There are plenty of free tut's but I was happy to pay for these.

[sparksue]

The Material Tutorials teach us most of the materials? Okay...perhaps I will get it for myself as well.

Thanks for the advice and the name for me to notice on it as well. Cheers!

[alienretro]

As I was slowly getting into this whole shader (or material) thing, I've realized that a whole better aproach to create a realistic material was to think about the surface I was trying to recreate as well. I have a set of questions that I ask myself that I'll try to share here.

 

A observation before I start: always have some reference pictures of the material you're trying to recreate. Your memory of the material is not enough, go on google images and search some good pictures to look at while tweaking it. If you get it wrong, other people will notice, so look at the reference!

 

1) What kind of surface it is ? What is the diffuse color ? Is it reflective ? How much reflective (reflection value) ?

2) How does it reflect the light ? Is it sharp as a mirror or is it a more blurred reflection ? Does the surface has fresnel reflections ? Most surfaces, except metals have fresnel. Set the Fresnel IOR properly. Remember anisostropy when simulating metal.

3) Are the reflections colored ? (case of most metals).

4) Does it refract light ? Is it transparent, somehow ? If so, how much light does it refract and what's the IOR for that material ? (There's IOR's list all over the internet). You can have a colored refracted material by playing Fog Color and Fog Bias.

5) Usually there are two types of detail in the bump. The high frequency detail and the low frequency. You usually want to use a bump map to simulate the low frequency detail, the small bumps and wrinkles in the surface. For the high frequency detail (deformations that occurs all along the surface) you may want to mix your bump map with a noise map. That noise map has the effect of warping the surface just a little to give a realistic effect. After all, it's very rare that a surface it's perfectly straight in the real world. And that affects reflection a lot.

6) Last, but not least, you gotta think about the translucence of your material. Think about a leaf and how light shines through it. For that, you can use VrayFastSSS2.

7) VrayBlendMtl is a great tool to achieve realism.

 

So, that's my workflow. I see that you got it all right for the basic maps, I'm just talking about my general process of seeing the world before recreating that world. Hope it helps.

[sparksue]

Hi Alienretro,

 

Thanks for the advice! Yes, I am actually looking at the IOR, but I am not sure how can I start with I notice that tweaking the IOR will increase the render time. (Am I right on this?) Which is why I always didn't play with it.

 

Do you have any link that I can understand more about the usage of IOR.

 

P.S: To get the Frensel IOR, I need to check the Frensel reflections and uncheck the 'L' to adjust the Fresnel IOR. Am I right to say that? What about Refraction IOR? Do I need to touch as well? (Meaning If Acrylic glass IOR is 1.490, I will need to edit both IOR?) Do you have a link for all the IOR numbers? It will be great if you can share those for us who are interested to work on their renders.

 

As I was slowly getting into this whole shader (or material) thing, I've realized that a whole better aproach to create a realistic material was to think about the surface I was trying to recreate as well. I have a set of questions that I ask myself that I'll try to share here.

 

A observation before I start: always have some reference pictures of the material you're trying to recreate. Your memory of the material is not enough, go on google images and search some good pictures to look at while tweaking it. If you get it wrong, other people will notice, so look at the reference!

 

1) What kind of surface it is ? What is the diffuse color ? Is it reflective ? How much reflective (reflection value) ?

2) How does it reflect the light ? Is it sharp as a mirror or is it a more blurred reflection ? Does the surface has fresnel reflections ? Most surfaces, except metals have fresnel. Set the Fresnel IOR properly. Remember anisostropy when simulating metal.

3) Are the reflections colored ? (case of most metals).

4) Does it refract light ? Is it transparent, somehow ? If so, how much light does it refract and what's the IOR for that material ? (There's IOR's list all over the internet). You can have a colored refracted material by playing Fog Color and Fog Bias.

5) Usually there are two types of detail in the bump. The high frequency detail and the low frequency. You usually want to use a bump map to simulate the low frequency detail, the small bumps and wrinkles in the surface. For the high frequency detail (deformations that occurs all along the surface) you may want to mix your bump map with a noise map. That noise map has the effect of warping the surface just a little to give a realistic effect. After all, it's very rare that a surface it's perfectly straight in the real world. And that affects reflection a lot.

6) Last, but not least, you gotta think about the translucence of your material. Think about a leaf and how light shines through it. For that, you can use VrayFastSSS2.

7) VrayBlendMtl is a great tool to achieve realism.

 

So, that's my workflow. I see that you got it all right for the basic maps, I'm just talking about my general process of seeing the world before recreating that world. Hope it helps.

[alienretro]

Here's a IOR table: http://forums.cgsociety.org/archive/index.php/t-513458.html

 

Setting the IOR right is pretty important to get the right look. The IOR determine how light will bend when it goes into that surface.

 

http://viscorbel.com/vray-materials/

 

On this link, he talks about the fresnel effect.

 

P.S: To get the Frensel IOR, I need to check the Frensel reflections and uncheck the 'L' to adjust the Fresnel IOR. Am I right to say that? What about Refraction IOR? Do I need to touch as well? (Meaning If Acrylic glass IOR is 1.490, I will need to edit both IOR?) Do you have a link for all the IOR numbers? It will be great if you can share those for us who are interested to work on their renders.

 

If the material is refractive I keep the Fresnel IOR locked and set the IOR only on refraction, only unlocking the Fresnel IOR if I need some finer control (sometimes being "physically accurate" isn't the best thing). If the material is not reflective, I just unlock it and put the value there.

 

And... you know, go out there. Look, see, make some observations, try to create the material only in your mind while looking at it.

[sparksue]

Note on this. thanks for the advice!

Will have to give a try soon.

 

Here's a IOR table: http://forums.cgsociety.org/archive/index.php/t-513458.html

 

Setting the IOR right is pretty important to get the right look. The IOR determine how light will bend when it goes into that surface.

 

http://viscorbel.com/vray-materials/

 

On this link, he talks about the fresnel effect.

 

 

 

If the material is refractive I keep the Fresnel IOR locked and set the IOR only on refraction, only unlocking the Fresnel IOR if I need some finer control (sometimes being "physically accurate" isn't the best thing). If the material is not reflective, I just unlock it and put the value there.

 

And... you know, go out there. Look, see, make some observations, try to create the material only in your mind while looking at it.