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real 3D-geometry vs fake (normal/relief/parallax/POM=parallax-occlusion-mapping/etc)

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Original post by lc_overlord
Quote:
Original post by Fingers_
Part of the "problem" is the process of creating and storing 3D geometry vs. a heightmap for the parallax shader. Textures are very convenient in comparison to 3D models. If the entire world were to be modeled in sub-inch density polygon mesh it'd obviously take a lot more time to create than just using tiled textures on less dense geometry.

One would think so, but it really does not take that much longer, most artists actually do a ultra high res version first(for normal maps) and from that create a low res one, this lowres version takes about the same time to make no matter if it is 15000 or 500 polygons.


Yeah, especially with "Sculpting"-type modeling becoming increasingly popular (zBrush, Mudbox, the newest version of Blender and XSI as well, though not 100% sure about the last one) high-resolution meshes have become *very* easy to make. Heh, even *I* can make 'em, and I'm no (visual) artist by a long shot:

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Yes, but it's also true for other non sculpting softwares like lightwave, it's pretty easy for a professional artist to create millions of polygons by hand in just a day or two.
And when it comes to the low res approximation mesh it gets easier to get a good fit the more polygons you use and therefore it takes less time to make than if you use a lower res mesh.

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It's not as easy to constantly work with & re-use high detail meshes. Most of these techniques are general purpose -- you can use the textures & shaders on arbitrary geometry and it will 'just work'. Workflow is becoming just as important as performance.

To give you an example: If I'm building a level and I want a bumpy floor, it's far, far easier to just apply a texture to the floor compared to manually placing multiple high resolution tiling meshes. The bigger the mesh the less flexible it becomes. A specialised floor mesh for one room won't necessarily work for another, so you often have to break it down into multiple 'snappable' tiles to keep the re-usability high, anyway (which makes it more fiddly & less unique). It can be the difference between manipulating one polygon versus scores of high poly meshes. If the room changes (say the gameplay requires tweaking) then the mesh(es) have to change with it and that's more work & hassle. If your bumpy floor is generated using a technique like POM, it'll likely be more flexible to work with.

IMO you use what works for a given situation. Sometimes there's no replacement for the real thing, whereas other times it's far more convenient to use other techniques.

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Quote:
Original post by Defrag
To give you an example: If I'm building a level and I want a bumpy floor, it's far, far easier to just apply a texture to the floor compared to manually placing multiple high resolution tiling meshes.


Hmm, I don't think the discussion of "how easy is it" to create a texture vs a highly detailed poly mesh is too relevant. If you want to tessalate some triangles based on a texture map, there's plenty of free software to do this.

Regarding the poster's original question, "is it better to use actual vertex data vs image-space techniques", of course the answer is "it depends" (as others have already mentioned).

I was going to write up some comments here, but I think the DX 10.1 slides from gdc 2007 http://msdn2.microsoft.com/en-us/xna/aa937787.aspx explain what I was going to say even better. The talk about on-demand tessaltion and subdivision, done on either GPU or CPU is really the direction I think graphics is ending (computations split between CPU and GPU now that CPUs are becoming more parallel and GPUs are becoming more general).

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