Suggestions on Coloration

[yourfather]

Hello.

 

Im trying to reproduce this brick for a client. It looks like im going to need to use displacement for the rough texture. I sorted that out in another thread.

 

However, the client now says that the light should penetrate the stone a little bit. Like subsurface scattering.

 

However, I seem to think its more of a colored shadow picked up from the stone color itself. Can anyone help me in determining what would be the best way to create a material like this?

 

I understand that the one on the left simply has yellowish light, so the rock has yellow shadows. But even in the middle one, you see more of an ambient color for shadows instead of a gray.

 

Please note, im using the daylight mr sun for lighting.

 

[Crazy Homeless Guy]

Post a your rendering as well so we can see where you are at and offer advice on how to fix it.

 

My best guess would be to render an AO pass for the stone and then adjust in post. Trying to tinker with stuff in the render engine is to time consuming and not enough control/direct feedback.

 

EDIT: You need to correct your user information as well. Board policy.

[yourfather]

so i would just take the AO pass and change the color of the pass to some yellowish color and mask out the other parts of the image? I can do that.

 

What do you think about my clients comment of the stone having some subsurface scattering? would you agree by looking at that stone? Or do you think what he is seeing is the colored shadows?

 

 

What do I need to correct? I will do it Asap.

[Crazy Homeless Guy]

The suggestion of an AO pass was just a starting point to give you something to start playing with in Photoshop. In the end it will probably be 3 or 4 things you need to adjust in Photoshop to get the effect of the stone.

 

There is a good possibility that light is penetrating the surface of the stone, or the stone has some other natural characteristics that make it feel special that aren't being captured in the current rendering.

 

I am just throwing suggestions at the wall without knowing what the rendered stone looks like.

[Francisco Penaloza]

Yes an image with your setup will really help to see what you need to do to replicate this situation, now I know this stone, and yes it may be a little translucent but not the way that your client imagine, this rock is also very reflective, so from those pictures it is all about light temperature and color balance, and all that can be controlled in photoshop.

 

Now if you are using mental Ray throw some photons also will accentuate the color bleed, if that's what you want, but honestly, it is all post production for me. I am pretty sure you are not rendering an extreme close up of that rock with a light fixture right on top of it, if so even then the translucency will be right in the edges of the brick, very minimal.

[yourfather]

Francisco,

 

may i send you a "region render" of the brick wall? I would post it here on the message board but my client is sensitive about posting images that havent been completed yet.

[Francisco Penaloza]

I guess you can send a region render, but my point was actually, depending your scene, your light temperature and everything else, that little translucency of the rock will be almost invisible, I am pretty sure your client is reacting more to the color balance of your indirect illumination and color bleed than the actual scattered light from the stone, again is almost minimal, how you can see in the photos that you post, the first image is very warm overall, the second image is less warm, and the last one is more neutral. I would just render the whole scene and paint the stones in Photoshop later on, maybe using the AO pass as mentioned early by Travis.

[yourfather]

Thanks Francisco. I will try to sort it out before sending you a test.

 

I posted a sample of the bricks im trying to create but the texture/modeling is getting the best of me.

 

A member suggested using the "stone wall placement" script which works great. However its not making the rocks surface bumpy enough. The sample below shows larger bumps. This is what im tring to do. Would i need to use a "normal map" to get this type of definition? Or do you think the displacement modifier would work best?

 

 

Image from the squaretexture.com website.

Edited January 27, 2014 by yourfather

[Crazy Homeless Guy]

However, I seem to think its more of a colored shadow picked up from the stone color itself.

 

 

I feel you are thinking to hard on this one. It sounds as though you had it out of the gate with one of your initial comments in the quote above.

 

Base don that quote you could solve this by rendering a few passes and using those passes to isolate the shadow color mentioned above to adjust the tint, color, etc... until you have it looking like what you are seeing in the photos.

 

Render a shadow pass, AO pass, matte pass, and light pass to help isolate and adjust the shadow until it matches what you are seeing in the reference photos.

 

Sub-Note:

Instead of posting the entire rendering for review here you can always isloate the material and post a rendering of it.

Edited January 28, 2014 by Crazy Homeless Guy

[yourfather]

Thank you Travis.

 

I will definitely be using that technique. Selective color (in photoshop) will help me isolate color moves to the shadows as well. I will be using all your tips.

 

However, I'm now back to the modeling challenge.

 

1. If i use something like the "stone placement" script. It only gets me so far. I have made a 12"x12" section of stone (3 bricks wide by six bricks high). I then go in and change the settings of the modifiers (to obtain the required look). But this makes crazy detail thats too much to render. With just a small section of bricks (about a 12"x120" area) I have more than 20 million faces. I need an area thats 40"x120".

 

I would probably go this route but the displacement on the bricks is rough on all sides. I need smooth on all sides except the ones exposed. But if i want displacement only on one face, i think i need to make each brick individually. Thats approximately 500 bricks.

 

2. I can use another script which will make a bunch of boxes for me the right size, and pattern. But very clean edges. Maybe too clean. However, I can then make a bunch of bitmap images (hopefully only 100 unique bitmap images) and map them. However, i think there will be too much repetition. And i still have the challenge of trying to make a natural edge for each of these boxes.

 

If it was just five bricks i can do it easily without asking all these questions. But with approximately 500 bricks, its a completely different story.

 

 

Anyway, i won't bore everyone. I'll keep my posts to a minimum so when I'm in real trouble, you guys won't be sick of me.

Edited January 28, 2014 by yourfather

[John Dollus]

posting an image of a 6ft x 6ft wall should not upset your client at all and would help us tremendously to provide more specific direction.

[Francisco Penaloza]

Create a good stone wall texture is always a pain and a big task so do not feel alone, we all been there some time.

Since you seems to have time and the will to do it it once and for all I would recommend just model a big enough portion, lets say 6'x6' or 10'x10' something like that and use all the scripts and plug in that you can just to get the result you like, then since that mesh will be giant for sure, you can use it to create a bump map, Displacement map and Normal map. You can combine all these maps later on in a simple wall and get almost the same look of the original mesh, this is what Game designers do all the time, I think Bertrand B. one time explain something like this for one of his projects, you may try google.

or just look high details mesh to low polygon tutorials, where they explain normal map creation and stuff. for your advantage we can use VRay displ map way more than just a simple normal map to get sharper edges.

 

But this way you can get the best of both world, high poly mesh details and models and low polygon count.

 

Hope this help

[Crazy Homeless Guy]

Here is a method to build a stone wall that your maps can then be mapped onto.

 

I would download this instead of streaming it. 68mb's

http://www.dreamthinklab.com/misc/forumpost/BuildWallStone.wmv

[Nic H]

you could use a good map in conjunction with a displacement map and it will look great with some normal lighting

no weird transulcent stone needed imo