Material environment and special excluding tricks

[gabrielhildebrand]

Hi there,

 

hope someone is able to help me. I got a situation where I need more reflection on a metal surface material but not any other scene materia/obj. I'm using vray 2.4. Scene is lit with vray light, a vraysky in the enviroment slot (8) and physical cam. No override. No domelight.

I coming from the mentalray department from the past. I was used to the material environment slot (in the map roll out). But somehow it not that straight forward with vray.

On a blank test scene the slot seems to affect the reflection but not what I would call enviroment reflection.

The one point I think I may have wrong is the mapping type (tried obj/world/screen) and the other, any condition I'm not aware of that disables the enviroment slot.

Didn't find anything in the vray manual and this question seems pretty uncommon on the net.

Does the material environment slot actually work with vray and what do I need to take care of that its working like a domelight reflection?

 

Any other solution other then using a domelight and exclude?

 

Which takes me to the last question. How one can exclude obj from direct lighting and not "just" GI/shadow?

[Nicolai Bongard]

The environment slot works. You just maybe perhaps do not have a sufficiently reflective material on your objects?

 

If you are aiming for a plain metal material you should not really input a texture into your reflection slot (unless you are perhaps trying to go for a brushed metal look, then you could try experimenting i guess). Try to start with making a material with a dark diffuse color, a rather light grey in the reflection slot (around 180 may be a place to start), set the reflection IOR to something like 20 and set your BRDF to ward. Then it should kinda look metal-ish and reflect quite a lot. To control the reflection you could either tweak the IOR number or make the reflection color lighter.

 

With a vray domelight you can set it to just affect what you want; diffuse, specular or reflection. Instead of excluding every other object in the scene, just include the one you need. However i do not think this would solve your problem with the not so reflective metal.

 

As for the mapping type of you images; it would make sense to have a spherical image (like typically an environment hdri would be) and set the map type to spherical wrap or whatever it is called? At least that is what you tend to do when you input hdri environment maps into domelights.

 

Last one: right click on your object and click vray properties and look through that menu, you should find lots of options there. You could also right click and go to object properties for some other options. Thats where i would start looking.

 

Sorry for the rather messy reply, really tired. Hopefully some of this makes sense.

[gabrielhildebrand]

Hey thanks for your reply! Well I'm using the vray obj properties more often then I should

The material is nearly exactly like you described. Just not using Ward but Blinn with -0.2 anisotropy and and a light scratchy reflection map. The problem and the ideal solution would be to use the material env. slot as the scene itself is how I like it but this metal isn't really working now because of missing environment information in the scene itself. Of course I know its kind of hacking. But well its CG.

What I tried in the env.slot:

# Hdr with vrayhdr (spherical/angled)(how do I know in this case how much overall multiplier I need?)

# Vraymap with a flatten jpg of a hdr

# Bitmap with the jpg version with screen, obj xyz, world xyz and explicit uv channel uv mapping

 

And in all of those tests. No difference. All I was seeing was the scene env. reflection I had without the evn slot.

So in general the slot works? If I use the Vrayhdr map I only need to set up the map type and no need to mess around with the mapping typ below of maxs internal option dialog for this case?

 

thanks for reading!

Edited April 18, 2016 by gabrielhildebrand

[Corey Beaulieu]

I think your problem is not all that clear to me. You may describing it, but I don't fully understand what you are after.

 

To get nice reflections on an object should not require endless trickery, but rather a solid setting of the material. Truthfully, with Vray, the simpler the better in the beginning. Grant WArwick has a bunch of tutorials that you can follow for the complicated version of what you are after, but if you just want it to work, make it glossy and make it reflective. And use a higher IOR.

 

Maybe post your material?

 

In the end, if you want a trick, just print a render elements called VRayRawReflection. with this you apply it post with a mask to increase the reflection of any object as if it were a pure mirror.

[gabrielhildebrand]

Well. My problem is I don't get the material env. slot to work. I see no reflection of the map I put into the env. slot of the material. The material works as it should but not so great in that scene because the scene itsself has less environment information than my usual scenes. The mat isn't way different that one that Nicolai Bongard suggested.

Blinn, 19 IOR, light scratchy map in the ref. slot at 30%, ref. grey at 200, -0.2 anisotropy.

Maybe I got something wrong with the mapping type. Even if I toggle the map preview. Or maybe there is a condition by vray where the slot is disabled. I know how the slot works in mental ray. But with vray he doesn like me

 

//EDIT: Ok got it to work in a blank test scene with the same mat and obj. Have to be a problem in the scene. I'm on that.

Still not sure how to exclude an obj from direct light. but this question is not related with this material

Edited April 19, 2016 by gabrielhildebrand

[Corey Beaulieu]

Select the light. There is an "Exclude" button in the Modifier panel. Choose the object you want to exclude.

[gabrielhildebrand]

Select the light. There is an "Exclude" button in the Modifier panel. Choose the object you want to exclude.

 

Well as I said above that exclude type works for illumination and shadows cast. But the direct light still affects the diffuse channel. The questions was if one knows how to exclude the direct light.

[Nicolai Bongard]

There are 3 checkboxes on the light. There you can choose if the light is going to affect diffuse, specular or reflections on the objects in your scene. This applies for all the objects in your scene that the light is going to hit (as in everything that is included, or not excluded, or if nothing is added to either lists, everything).

[Casey Hawley]

Use a dome light to simulate sky light. Assign HDRI to the environment reflection override slot in vray render settings. This is for overall global env reflections. Put desired 'other hdri' in material environment slot. Then, for any object that you want a different enviro reflection, put a dome light with affect reflections only and set it to include only those objects. Exclude those objects from the 'sky' dome light.

[xoserodriguez]

Are any other way rather than include a second dome? is it not a way of eliminate reflections on a specific object that cames from HdRI image set in the dome light.