Shawn asked that I post his reply to the list. It is included below after
my response.
I may be missing something here. I am not saying they are using one large
texture. What I am saying is that I think they are using a grid of
textures, each one laid out side by side. I really don't think they are
getting resolutions at the cm level. I haven't look at the movie, just the
still shots, so maybe you are seeing something I am not seeing. They speak
of layers from the artists persecptive. It looks to me that their artist
sprays an alpha blending on one layer, letting the next layer show up. I
sincerely doubt they are blending 6 layers at runtime. I will give it some
more thought, and I will see if I can reproduce something like this.
Whatever they are doing, it sure looks good!
Dave
----- Original Message -----
From: Shawn Kendall <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Saturday, December 02, 2000 12:15 PM
Subject: Re: Multi-texturing and what is possible?
Daivd,
I think you are missing that's really happening. Everyone I have shown
this to has responded the same. "Yeah that's not so bad, we can do
that...". And then they take another look. They are NOT using
multi-resolution images (other than the regular mipmapping). The textures
are wrapped. There are layers of wrapped textures that blend between each
other on the triangle. It is not in the texture.
A 128x128 for 100m x 100m would never cut it. Take a look at the pix and
the movie again. The texel density is around the cm level. You can't get
that with one big texture. It would have to be 10000 x 10000 pixels for
100m x 100m! You could use detail textures, but then you would see the
seems.(this is the problem you and I are having right now)
Also, the texture clearly repeats. If the terrain map was one big texture,
repeating would be an unbelieve waste. You could guarantee variance
everywhere with a single giant map. This is actually how they do the
terrains for many flight simulators, using satelite data. But only on the
big SGI's that have hardware texture paging, and they STILL don't get the
close up result you see in UT.
Read the article. It explains that they use 6 layers to get this effect.
That's 6 texture layers not image layers in PhotoShop.
We just had a game artist over from Acclaim this week, and he did the double
take as well. If fact, he said they could NOT do this on a PS2 without
sub-faced polygons.
Once you examine it in depth, I think you'll see it can't be one texture.
So the question is, is this kind of blending possible in Java3D?
P.S. Please forward this reply to the list for me. I can not from this
emial address. Thanks
====================================================================
Shawn:
I don't think they are doing anything magical. His description of how the
textures are being generated are very similar to the techniques we are
using. The multitexturing he is doing, if any, is just for shading, but I
believe they are using high density texture cells using several different
blending algorithms. It looks like he is willing to pay a high price in
texture memory, but take another look at the rest of the images in that
article. Most are being taken at some height, which we know always favors
texture rendering of over stretched textures. But look at terrain3 from
their scenes, the only one that is ground level and you can see a fair
amount of stretching. My guess is they are using 128x128 textures per 100m
x 100m cell. The textures are mipmapped so its only the close ones that use
all the memory.
I am pretty sure I could reproduce those exact shots using our engine.
The way we have written the texture generator I can ask the engine for a
texture over any space and at any resolution and it returns the appropriate
image. This is great for increasing precision for "closer" shots. So I can
ask the engine for a 256x256 texture covering a 5km x 5km area, or ask for a
128x128 texture for a 100m x 100m area and they both will be right, just one
will be more localized with more detail.
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