Pebble test!

A little test I did to try and make 3d pebbles without modeling each one:D
You may see the technique in my next scene…:eyebrowlift2:

Photoshop? can’t be.

What do you mean? Lol…

Hey! looks, like a good result! what’s your method if you don’t mind sharing :slight_smile:


No matter how hard I look it I just can’t find some kind of pattern of it… damn you’ve made great job :slight_smile: Is there toon-edges? I really like the results

Okay. I’ll bite. My guess would be a transparent PNG, alpha mapped in Blender. Possibly a digital photo of the real thing on a solid-colour background for easy removal. The corners look like they suffer from spherical aberration.

Would certainly look good - and save time - in a scene.

Ok, I’ll reveal my method. AndyD’s almost right.

  1. Take a photo of some rocks.
  2. Make a copy of the photo and turn the contrast way up, then change it to black and white and blur it slightly.
  3. Make an object in blender with several planes stacked on top of each other. (The more there are the better it looks)
  4. Map the black and white image (which looks like a whole bunch of white rocks on a black background) to the object. Set it to control alpha.
  5. Map the original picture to the plane and set it to affect colour and nor. This way the actual pebbles will each have their own texture.

It takes a while to render, but looks ok. I partially stole this technique from a thread here a while ago about volumetric material. I think it works pretty well though.

EDIT: Here’s a render with more layers…note how they look basically solid even from side view.

Could you post your blend file?

Ah, did you use closely stacked planes or did you go all the way and put rows of planes on the X, Y, and Z axis.

Looks good despite the mipmapping making them blurry in the back.

Mivrex: Sure. I don’t know where to post it, though…
Cyborg Dragon: I used closely stacked planes. I tried x and y too, but it wasn’t necessary.

Dude, you do know you did’nt really have to take a picture of rocks, could’ve just used a procedural, but then agian you may not have the same affect, when I get my comp down to texas (or when I get a new one) I’ll show you guy’s how to get some could “stones on the ground” affects on Blender .

Dude, I wanted each rock to have it’s own texture!:stuck_out_tongue:
But yes, procedurals would work too.

Modified this somewhat. Made 8 different levels for the alpha maps each with slightly less white in them. This was achieved by taking the original B&W image (before blurring) and blurring it 0.5,1.0,1.5 pixels and so on with a Gaussian blur. Then select just the 255.255.255 pure white with the magic selector tool with contiguous turned off. Delete anything that isn’t pure white and leave it black. I did this 8 times with the increasing levels of blurring giving less and less pure white as it went on.

Then I made 8 different planes and added the alpha maps from 0 to 7 to each one. Here is the result:

Heyyy… that’s pretty niiiiiiiiice…:cool:
The only problem is, how to make more layers without doing them manually?
What if you duplicated everything you had there to make it more dense?

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Well the density depends on the texture that you start off with. The one I used had some gaps between pebbles in the corners as you can see. You could increase the brightness before increasing the contrast and that should leave you with more white areas in your alpha maps.

Darg: The pebbles you show are blurry, to get a nice sharp look you should have have an extremely sharp transition between the white and black in the alpha map.

Neat technique. Thanks for sharing. :slight_smile:


This calls for a “generator” script. F*** I don’t have time atm. Btw would it be possible to use blur in texture panel or must be map blurred in image editing prog?

Cyborg Dragon: Yes, sharpening the image would make each rock look more solid, but would it not reveal the edges of the planes? So more layers would be needed I’m assuming.

iluvblender: Thanks. And you’re welcome:p

tedi: Actually I thought about blurring it internally (“filter” button I believe). But you would need to use an external program to adjust brightness/contrast anyway.

Isn’t there brightness/contrast control for bitmaps in texture panel? Don’t know if could be accessed through API which can be a limiting factor.

Anyway interesting, if that could be automated, the better.