Asteroids

[Primalace]

This is my latest work in progress. I'm hoping to get some advice on how to complete the image. I want to add thousands of tiny rocks floating between these 3 large asteroids but I've been having difficulty doing it. Any ideas?

I'm thinking I could use a fake stone shader on a plane and use the same shader to mask the surface of the plane, so only the rocks are visible. But then all the rocks will be on the same plane and I want them positioned all over the place. Also will doing this cast shadows on anything beneath the plane?
-Mike

[FrankB]

That's the problem: you cannot populate objects in a volume, only on a surface - be it a surface of a planets, object, or mask.
At least, I have never succeeded doing otherwise.
So your last resort may be playing with an optical illusion, by working with various disctinctively tilted planes, upon which you create rock objects of different sizes.

Frank

[Henry Blewer]

What if he used a height field with the alpha on full for the surface shader? It could be populated, but not be seen in the render.

[freelancah]

Hmmm... an idea: How bout create a rock object population..  distribute them on a plane and add a powerfractal to it. Rough and high displacements. This way they would be distributed somewhat "all over the place". If one population isnt enough add a few more.  Remember the compute terrain node or it wont work.

[cyphyr]

Try using a "plane" object (or several) as your "sit on" terrain. Displace this as you would a planet with scaled PF's.
Should work.
Richard
yep, works, see attached
Just read what freelancah wrote before me and he beat me to it, by a good few hours, I should read complete threads before responding lol

[freelancah]

Oh but you went a step further and actually tested it. Nice work

[Primalace]

Thank you, guys, especially freelancah and cyphyr. I had a quick play around with that .tgd and the results were very promising. However, I couldn't figure out how to displace the rock objects surface. I plugged a regular power fractal into the surface shader of them but nothing appeared to change. I played around with various scales and displacement amplitudes to no avail. Any ideas about what I'm doing wrong here?

[freelancah]

Im not sure since i havent played with it much but I believe its just a normal object so you might not have much luck in displacing it with powerfractals. Smallscale stuff might work but nothing major. You'd probably have better luck creating those asteroids using the planet object and populating those. I remember reading about problems with the rock object displacements before too.

Or a a second option: Create few asteroids in a 3D application and use those in the populations. Creating asteroids shouldn't be very difficult. Just play with some noise modifiers.

[freelancah]

Hmm also Im not sure if it is possible to populate the planet object. I did some tests but they didn't work out. Anyone got a solution?

[Primalace]

Here is an update. It's looking a lot better in my opinion, though I've not had a long time to play with the displacements on the planes controlling the rocks positions. It also doesn't look like the powerfractal used as the surface shader for the rocks is actually working as the rocks are all white :S I'm also going to reposition the larger asteroids to sit on the same plane as the smaller ones.

[Henry Blewer]

This is looking really good to me. Keep working. You'll get it the way you want it!

[freelancah]

I can toss you a few asteroid models when I get home. I dont think you can displace the built in rocks good enough with a procedural way because the powerfractal only displaces the faces of the object. Also I dont know why the "planet asteroids" cant be populated. They do have an output so basically it should be possible. I do get them to populate but they dont render for some reason.

[Primalace]

Yeah I started doing that at first and had to quickly give up and do the larger asteroids myself. I like the rock population though I do wish they would colour properly and it's a shame they can't be displaced much. If I increased the number of faces would that help? At the moment they are only using 16-24 faces.

Also any asteroid models that would work in Terragen would be greatly appreciated. I tried going down this root myself but I had loads of problems importing them into Terragen and getting them to render without holes in them so I gave up

[freelancah]

Here's an asteroid. I have a few more if you need but if you dont need closeups one should be enough.. Rar contains tgo and the imagemap for the texture. http://smattila.pp.fi/Random/asteroid/asteroid.rar
You might have to adjust the path of the texture image but other than that it should work.

[Primalace]

That's amazing, thank you so much! I'll see how this looks on my scene after I have a real good go at getting the planes displacements right.