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Rune wrote:
>
> In which of these two images does the grass look more real?
>
> 1: http://rsj.mobilixnet.dk/3d/include/fgrass.jpg
>
> 2: http://rsj.mobilixnet.dk/3d/include/fgrass2.jpg
>
> ...and why? ...and what can be improved?
1. Looking strictly at the grass, it's hard to say, but the flowers in
2 look like they're just floating, and I think 1 has a much nicer blend
into the path.
--
David Fontaine <dav### [at] faricy net> ICQ 55354965
My raytracing gallery: http://davidf.faricy.net/
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Don't like 1, blades are too bent or seem to have too many curves.
No opinion about 3 but can't explain why :-/
Like 2 best, I've seen better, but I would be happy with that.
Alf
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I like grass2 best too. Some reference images from corbis.com:
http://www.luxlab.com/ref/grass/
Maybe you could add fake shading.
_____________
Kari Kivisalo
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"Kari Kivisalo" wrote:
> I like grass2 best too. Some reference images from corbis.com:
> http://www.luxlab.com/ref/grass/
Very good reference images. Thanks!
Looks like grass has a much more crisp green color than I remembered. Unless
the photos have been saturated artificially that is, but I don't think so...
> Maybe you could add fake shading.
I don't think that works with the method I use...
Rune
--
3D images and anims, include files, tutorials and more:
Rune's World: http://rsj.mobilixnet.dk (updated Feb 16)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Ring: http://webring.povray.co.uk
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An excellent job. I'm voting for Number 2 so far. It looks the way a
recently-seeded lawn looks as it starts to sprout in the spring.
A quick look at the Corbis reference images reminded me of just how
surprisingly green grass actually is, especially early in the year. It
doesn't seem to bend in any single direction unless the wind is very
strong. In scale it can be rather more thin than memory would have it,
and there's usually a great variation in blade height in any unmown
grass. Long grass can be branchier and more tuft-like than one would
think. In the Midwest US where I live, I've noticed that wild fields of
grass (up close) have much variety of texture and species, lots of
little sticks and brush and weeds sticking up, etc-- clutter, in other
words. All on top of mats of dried matter from previous seasons: the
dirt almost never shows through in a wild field.
I'm sure you've run up against the biggest issue in creating CG grass:
creating
enough bejillions of blades to approximate nature. Limitations of memory
and processing time tend to see to it that the blades must be much
sparser than in a real field, which is so jammed with life that even
from a short distance the grass looks like fuzz. I've often thought that
individual blades may be best for the parts of the scene that are in the
foreground and middle-near, while some other method (one or more layers
of variagated procedural texture?) be used for the background. Sometimes
height-dependent background textures seem tempting, as color and
lushness often vary with moisture levels.
All in all: nice stuff.
DZ
Rune wrote:
> In which of these two images does the grass look more real?
>
> 1: http://rsj.mobilixnet.dk/3d/include/fgrass.jpg
>
> 2: http://rsj.mobilixnet.dk/3d/include/fgrass2.jpg
>
> ...and why? ...and what can be improved?
>
> Thanks in advance,
>
> Rune
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"DZ" wrote:
> An excellent job.
Thanks!
> A quick look at the Corbis reference images reminded
> me of just how surprisingly green grass actually is
Same here. In my newer message "Some grass" which you'll find below, I've
tried making the grass a bit more saturated. Still not quite as green as in
the photos though, because that just didn't look right in this image.
> I'm sure you've run up against the biggest issue in
> creating CG grass: creating enough bejillions of
> blades to approximate nature.
Nope.
> Limitations of memory and processing time tend to
> see to it that the blades must be much sparser than
> in a real field
But the whole concept of my grass is that it's a texture, not individual
blades of grass. So I have only two objects in the scene: two copies of the
same height_field, one translated sligtly above the other.
With my method memory and processing time is absolutely no problem, no
matter how big the field of grass is. :)
Rune
--
3D images and anims, include files, tutorials and more:
Rune's World: http://rsj.mobilixnet.dk (updated Mar 19)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Ring: http://webring.povray.co.uk
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Wow, that's cool! But how can suprimposed heightfields create the blade-like
shapes?
DZ
Rune wrote:
> > "DZ" wrote:
>
> > I'm sure you've run up against the biggest issue in
> > creating CG grass: creating enough bejillions of
> > blades to approximate nature.
>
> Nope. [...] the whole concept of my grass is that it's a texture, not
> individual
> blades of grass. So I have only two objects in the scene: two copies of the
> same height_field, one translated sligtly above the other.
>
> With my method memory and processing time is absolutely no problem, no
> matter how big the field of grass is. :)
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"DZ" wrote:
> Wow, that's cool! But how can suprimposed
> heightfields create the blade-like shapes?
It's actually not the superimposed heightfields that does it. One
heightfield would be enough, but then the horizon would not be fuzzy, and
that would reveal the illusion.
The trick lies in the special function used for the pigment. It, well, sort
of simulates 3d blades of grass being projected onto a 2d plane using
perspective projection. How to do that is something you know if you have the
ability to twist the concept of 3d around your little finger. Ok, just
kidding, but it's a bit difficult to explain... ;)
Rune
--
3D images and anims, include files, tutorials and more:
Rune's World: http://rsj.mobilixnet.dk (updated Mar 19)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Ring: http://webring.povray.co.uk
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I downloaded the source from your website. 3dnoise and sin/cosine-- that's
brilliant! Acres and acres of cheap, verdant POV real estate.
Nice job.
DZ
Rune wrote:
> The trick lies in the special function used for the pigment. It, well, sort
> of simulates 3d blades of grass being projected onto a 2d plane using
> perspective projection.
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"DZ" wrote:
> I downloaded the source from your website. 3dnoise
> and sin/cosine-- that's brilliant! Acres and acres
> of cheap, verdant POV real estate.
Thanks. :)
Though, the file on my website is my old Fast Grass Include File.
What I'm working on now is a better-looking technique which makes more
realistic grass which also work in animations. It's a bit slower though...
Rune
--
3D images and anims, include files, tutorials and more:
Rune's World: http://rsj.mobilixnet.dk (updated Mar 19)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Ring: http://webring.povray.co.uk
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