Ipr To Zbrush

[sibarrick]

Hi guys,

I'm just having another look at zbrush, and it popped into my head that now Houdini has IPR rendering it wouldn't be a huge leap to think of it as a door to zbrush 2.5D pixel manipulation, ie totally awesome sculpting.

Here's why I think this. A IPR render is a pixel by pixel store of the surface of a model with depth info, i assume it is anyway otherwise the re-lighting wouldn't work. Given that all you need to add is a way to sculpt that pixel depth information and store it in a map and you basically have the core feature of zbrush - yes? no?

Anyway just thought I'd float this out there as it were.....

[edward]

I've never used Zbrush but I always thought that their stuff was related to point based methods from their PR. A quick search on google revealed these links (I haven't read them):

http://myweb.hinet.net/home7/hks/Resource/...BasedPaper.html

http://www.labri.fr/perso/preuter/research/graphite/

http://www-sop.inria.fr/reves/Marc.Stamminger/pbr/

As you describe your idea, it sounds like just a deep raster? How do you deal with the pixels that you don't currently see?

[sibarrick]

Well..... it's only a half baked idea, as usual....

For 2.5D you don't need to worry about the bits you don't see, obviously that is only good for stills. But from reading the zbrush tutorials it looks like their full 3D sculpting makes use of the 2.5D method in the following way. The 3D model is rendered to the canvas and then sculpted on, when you want to rotate to a new view the displacements are baked back into the geometry. That means whilst you are sculpting you don't care about the bits you can't see. For big displacements you go back down the subdivision tree and sculpt the normal way (as in the current sculpt sop) on the low res geometry. When sculpting on the high res mesh you are just pushing pixels around - so yes in a way you are directly editing a depth map, of course the trick is to update the render in realtime using the modified map.

On the other hand maybe they just subdivide the heck out of the mesh and are just hyper efficient at handling millions and millions of polys, or covert to a point based method as you suggest, either way it just struck me that maybe this was another way of handling it.

As I say just another crazy idea maybe there's nothing in it

[edward]

Yep, I went to take a shower and realized what you meant and came back. So just like a 3D Paint application where you paint displacements in addition to colour. Per pixel displacements could probably be handled by the GPU these days. Houdini would need real 3D paint first though.

[sibarrick]

Yep, I went to take a shower and realized what you meant and came back. So just like a 3D Paint application where you paint displacements in addition to colour. Per pixel displacements could probably be handled by the GPU these days. Houdini would need real 3D paint first though.

23133[/snapback]

Well that was kinda what I was suggesting you could avoid, essentially you would be only doing 2D painting but modifying 3D data in the form of the IPR cache or a depth map..... But yes you would need a paint tool either way. What ever happen to ipaint

[lisux]

Well that was kinda what I was suggesting you could avoid, essentially you would be only doing 2D painting but modifying 3D data in the form of the IPR cache or a depth map..... But yes you would need a paint tool either way. What ever happen to ipaint 

23135[/snapback]

Yeah please, please a paint solution would be great. and based in GPU wow!

And i think that once you have true 3D Paint is not so difficult to have some tool like zbrush, true

[edward]

Er, btw, I'm sure Simon was joking about ipaint. It's still there if you want to run it (on Windows even).

[sibarrick]

Wow, i didn't realise that, forget photoshop ipaint rules

[altbighead]

Wow, i didn't realise that, forget photoshop ipaint rules 

23289[/snapback]

wow.. i am speechless.. ipaint rocks.. way better than mspaint