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mattnewport

Holographic Texture Mapping?

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In a recent interview about UnrealEngine3 Tim Sweeney mentions "entirely new things that haven''t been done in real-time before, such as holographic texture mapping, spherical harmonic lighting, and dynamic soft shadows.". Does anyone know what technique he''s referring to when he mentions holographic texture mapping? I did some googling and couldn''t find anything obvious. I''m guessing it might be something to do with lumigraphs / lightfield rendering (which I don''t know much about). Can anyone explain what he''s talking about or provide any links to relevant papers?

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Spherical harmonics isn''t a "real time" thing from what i can tell.. unless they are doing some sort of pixel shader function for a large amount of lookup tables. Dynamic soft shadows "ain''t no big thing" there''s various ways to do that now.

As far as holographic mapping, i would imagine it has to do with some interesting reflection mapping properites that change as the viewpoint changes towards an image.

~Main

==
Colt "MainRoach" McAnlis
Programmer
www.badheat.com/sinewave

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"Spherical harmonics" isn't a single technique - it's a tool that can be used to achieve all sorts of effects of varying complexity. Perhaps the simplest application of spherical harmonics is for Irradiance Environment Maps and that is very much a 'real time thing' - plenty of games already use that technique and it's pretty cheap when done per vertex. A more advanced application of spherical harmonics is for Precomputed Radiance Transfer and that is now a real time technique as well (you can see it in action in the examples with the latest DX9 SDK). The only problem with PRT is that it doesn't really work for animated models (at least no one's published a way of using it for animated models). PRT can be used for soft shadows, I don't know if that's what UnrealEngine3 is doing.

I'm pretty sure they're doing PRT in UnrealEngine3 because Tim Sweeney gave an interview about the benefits of 64 bit memory addressing for pre-processing models for spherical harmonic lighting.

[edited by - mattnewport on March 20, 2004 6:17:12 PM]

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I'm wondering if by "Holographic Texture Mapping" he really means using "Holographic Transforms for Image Compression". A way of taking multiple lossy compressed images and using a holographic transform to produce a near-lossless decompressed image. Such textures would be a breeze to stream off a disk or disc in real time due to their high-loss compression. Though it would be rather demanding of the CPU to produce the uncompressed images. Perhaps using a seperate thread (via a hyperthreading cpu or simply a second cpu) could elivate that problem by predictively decompressing textures a little ahead of the time they are needed. This could allow absolutely non-repeating textures for tremendously large scenes. And because of the holographic nature of the transform, you could literally decompress the images to the particular mip levels that are needed at that time.

I'm betting however he means something akin to lumigraphs.

[edited by - Mastaba on March 20, 2004 8:00:01 PM]

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I read a newspaper article about (edit)the new Tribes a few month ago. The journalist was talking about a new mapping process used by the Tribes team called normal mapping. According to the journalist, this technic will simulate that each object are compose of many many polygons. I think it's what they call now holographic mapping, you will understand.

In this time, I was implementing a correct perpective mapper and when I read the article, it came to me an idea: the mapping is directly join to the plan of the polygons. If you consider the vertices normals, you can interpolate a normal\plan (which is more correct) for each screen pixel and do a mapping with this new plan. You imagine easily the result. I implemented it quickly and it worked very well (but it was very slow, too slow for my software engine).

What do you think of that, it's maybe near from that


[edited by - Chuck3d on March 21, 2004 9:47:12 AM]

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Ooops ...

EDIT: what is behind holographic ? What is an holographic transform you mention?

[edited by - Chuck3d on March 21, 2004 11:12:01 AM]

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I agree with duhroach.
I think holographic mapping is "just" parallax compensated normal mapping.
And yes, you use SH PRT in real time; that''s the point.

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I don''t see why the term ''holographic'' would have anything to do with parallax mapping though. Maybe I''m missing something but it seems like a very poor choice of word if that''s really what he''s talking about. What makes you think that''s what he''s referring to? I did see a quote here which shows that Tim Sweeney is familiar with the technique and thinks it is impressive but I still don''t see where the ''holographic'' would come into it.

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