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View Full Version : Nurbs and UV maps, not playing nicely together



starbase1
08-16-2012, 03:25 AM
I was making a displacement mapped asteroid by applying displacements to a sphere. I started with something low poly, figuring the best way was just to hit the tab key, so I could experiment with the number of subdivisions required, and have a lower display level than render level.

I added a spherical UV map at this stage - my plan being to copy the displacements to the texture channel and bump channel so they follow the terrain. By baking this and saving transformed I figured I'd get a nice result which I could then run polygon reduction over.

While the displacement asteroids looked pretty much as I had hoped, the baking was a mess. It looked like it only had the original few points/polygons, and some areas of the asteroid seemed 'off the map' completely.

(2 shots of the nice result attached!)

Now I could increase the number of polys before I hit tab, but that's just going to reduce the problem areas rather than remove them.

So is there a good way to make UV maps that play nicely with nurbs spheres?

Lewis
08-16-2012, 03:39 AM
NURBS? What nurbs ?, how did you get NURBS work in LW ?

If you mean SubDs then switch your UV type to SubDs also instead default "Linear" mode.

Sensei
08-16-2012, 03:47 AM
Asteroid looks just great.

If I were you I would use another slightly bigger sphere (just couple percent bigger, enough to hold all mountains).
And make it invisible to camera. And use it in baking camera settings.

Like while baking from high-poly to low-poly.

starbase1
08-16-2012, 04:11 AM
Lewis - thanks, that sounds like exactly what I need.

Sensei - thanks for the kind words. I don't see what the approach you suggest will bring me though?

I've tried procedural asteroids before, but this is the first time I feel it is really working. The combination of ridged multifractal for the basic deformations, and IFW2 pebbles to indent craters seems to have done the trick.

The thing I'd most like to change now is to get the 'craters' to have raised rims, rather than looking like simple cut outs.

Nick

NinoK
08-16-2012, 12:09 PM
once you bake your UV Image map, you could just paint an additional "raised edges" uv map in photoshop since you'll be able to see your craters and use it as a displacement on top of your geometry to get more raise around the crater edges. Hope that makes sense. :p

starbase1
08-16-2012, 12:32 PM
once you bake your UV Image map, you could just paint an additional "raised edges" uv map in photoshop since you'll be able to see your craters and use it as a displacement on top of your geometry to get more raise around the crater edges. Hope that makes sense. :p

Yes - thats part of the plan!

Once I get the hang of this I can disconnect everything except the crater nodes and bake a 'crater map'. I can then tirurn this into an additional displacement layer...

starbase1
08-16-2012, 02:18 PM
Hmmmm... No joy.

Maybe someone else would like to play?
SCene and object attached.

starbase1
08-20-2012, 03:24 AM
I ditched the subdivisions and went for a simple high poly sphere. I was able to bake textures onto it, and got a binary asteroid I was happy with, (image attached).

So far so good.

But what I'd like is to reduce polygons while preserving the UV map, and when I tried this the UV mapping went awol.

Is there a decent way to reduce polygons and preserve a UV map? At a million polys for each asteroid, it's a bit extravagant!

I know that poly reduction is normally best avoided, but in the case of what is basically a rough rock, I think it should work just fine!

dee
08-20-2012, 03:56 AM
Is there a decent way to reduce polygons and preserve a UV map?

Try qemLOSS3: http://amber.rc.arizona.edu/lw/qemloss3.html

XswampyX
08-20-2012, 01:31 PM
I think you might have missed the point of baking your displacement/normal map.... You make a new Low-res model and UV map that. Then you bake the displacement/normal to that UV map. The hi-res one doesn't need to be UV'd.

http://i465.photobucket.com/albums/rr16/xXswampyXx/Asteroid_Disp_LW.jpg

starbase1
08-21-2012, 02:58 AM
I see what you mean - many thanks for taking the time to explain so clearly.

Thing is, that's not what I was trying to achieve. My two goals in baking were to get the textures usable outside of lightwave, via a UV mapped OBJ file, and to get the texture into photoshop (elements) where I can edit it.

For the editing I want to isolate the crater elements and bake them into a map. It should then be simple to remove the inner parts of the craters in the map, blur a bit, and use the result as a displacement map to lift the crater rims above the surrounding terrain.

For normal maps in Lightwave I usually find it simple and effective to simply use the bump-to-normal node from Denis Pontonier's excellent free additional node kit.