hi
can anyone tell me if it is possible to bake textures , including gi data and occlusion into 2d texture maps with houdini and mantra nad how to do it?

http://www.odforce.net/wiki/index.php/ShaderUnwrap [odforce.net]

Thanks for the link Jason - really useful.

Im a bit confused as to how it works - for instance when you put the command in the command line of the Matra ROP - do you then have to render out the model from only one still frame of the object, or do you need a sequence to show all areas?

Does it save the image out as a texture?

Is it different if you have an entire scene or one single object?

I've heard a little bit about this process and I am really interested to know more.

thank you for reply I will look it up and let you see if I did it ok

Hey Johnny, the mantra -u command renders all the surfaces of the specified object in the manner that you laid out the UV's of that object, like a shaded version of the UV viewport. It will render to mplay as usual, and then you can save it out as picnc and fix it up in COPs (otherwise there will be seams when you apply the baked texture). Here is an example scene. Just point the shaders to the location of the textures included in the zip file. The COP network for fixing the seams is also there.

http://www.geocities.com/stehrani3d/3dfiles/Baked_Cornell.zip [geocities.com] (Right Click > Save)

DJ thanx for example

DJ - thanks so much

Thats really cool that u offered a hip file - ill take a look when I have some free time (!) and will probably post some questions

Thanks again guys

J

Hi all,

I added to the documentation on the Wiki - with some images and a hipfile too.

Enjoy,
Jason

http://www.odforce.net/wiki/index.php/ShaderUnwrap [odforce.net]

Hey Jason

Thanks so much for the effort you have put into updating the Wiki - that is going to be so useful to me, and of course, future Houdini users.

I was wondering, bit of a newbie question here, but how does this effect moving or animated models - because obviously the ambient shading would change - eg if an arm is closer or further away from the body.

I assume this technique is only useful for static models such as the cityscape you supplied?

Thanks again

J

You are absolutely right - ideally you should be baking off a sequence for this, but then you may start to lose some of time you'd be saving in the first place, especially since you'll be spending time rendering the ambient occlusion on the backfaces of the character - areas of the model you don't see.

However as it turns out, the occlusion on a typical character is really there to hint in creases or folds and is usually printed in pretty lightly. It seems to work out fine to bake occlusion for a neutral pose (like the bind pose) and just apply if for the entire animation, especially if the character is moving fast or is small in frame. A close-up hero performance might still need to be a sequence.

If you have time, feel free to take that hipfile and try to render a character instead of that city model. (Feel free to add to the Wiki too) Of course, this technique works so much better for realistic characters over cartoon characters because of the added detail (incl clothing)..

Hope this helps,
Jason

im currently finishing off a compositing project using Houdini.

We used ambient occlusion on the render passes for the CG character, and even at 256 sampling quality the renders suprised me with how fast they actually were.

I will definitely be trying your hip file out when we have finished Jason, so cheers for your support


J