I used TonyB's modified version of Gilles Tran's mesh grass to compare how
mesh grass renders and looks compared to my faked grass.

Both images were rendered at 800x600 AA0.3, then scaled to half size before
posting here.

Faked texture grass:
~~~~~~~~~~~~~~~~~~~~
Time for parse: 0 min.  0 sec.
Time for trace: 5 min. 58 sec.
Time total:     5 min. 58 sec.
Peak memory used:  0.36 MB


Real mesh grass:
~~~~~~~~~~~~~~~~
Time for parse: 0 min. 10 sec.
Time for trace: 4 min.  8 sec.
Time total:     4 min. 18 sec.
Peak memory used: 15.09 MB

As you can see, my faked grass renders a bit slower. The real mesh grass
renders quicker, it doesn't use particularly much memory, and it parses in
almost no time. I expect that the fields of grass must be extremely huge
before my faked grass becomes more efficient than mesh grass...

However, my grass looks rather different than the mesh grass. It has a
softer look, which I rather like. I may be of course, that I just haven't
been able to tweak the mesh grass to look good in my scene...

Ok, I really don't know what to conclude, so I'll just let it be up to
you...

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

Post a reply to this message

Attachments:
Download 'grassreal.jpg' (33 KB) Download 'grassfaked.jpg' (21 KB)

Preview of image 'grassreal.jpg'

Preview of image 'grassfaked.jpg'

i think your faked grass sure has a more natural feel to it.  how does the
grass look from kind of close up?  reason i ask is cos im toying around with
the idea of a hadrians wall scene and i want the camera close to the ground
looking up towards the wall.

all the best,

john robinson


"Rune" <run### [at] mobilixnetdk> wrote in message
news:3cab1a31@news.povray.org...
> I used TonyB's modified version of Gilles Tran's mesh grass to compare how
> mesh grass renders and looks compared to my faked grass.
>
> Both images were rendered at 800x600 AA0.3, then scaled to half size
before
> posting here.
>
> Faked texture grass:
> ~~~~~~~~~~~~~~~~~~~~
> Time for parse: 0 min.  0 sec.
> Time for trace: 5 min. 58 sec.
> Time total:     5 min. 58 sec.
> Peak memory used:  0.36 MB
>
>
> Real mesh grass:
> ~~~~~~~~~~~~~~~~
> Time for parse: 0 min. 10 sec.
> Time for trace: 4 min.  8 sec.
> Time total:     4 min. 18 sec.
> Peak memory used: 15.09 MB
>
> As you can see, my faked grass renders a bit slower. The real mesh grass
> renders quicker, it doesn't use particularly much memory, and it parses in
> almost no time. I expect that the fields of grass must be extremely huge
> before my faked grass becomes more efficient than mesh grass...
>
> However, my grass looks rather different than the mesh grass. It has a
> softer look, which I rather like. I may be of course, that I just haven't
> been able to tweak the mesh grass to look good in my scene...
>
> Ok, I really don't know what to conclude, so I'll just let it be up to
> you...
>
> 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
>
>
>

Post a reply to this message

On Wed, 3 Apr 2002 17:05:13 +0200, "Rune" <run### [at] mobilixnetdk> wrote:
> Ok, I really don't know what to conclude, so I'll just let it be up to
> you...

Your grass is very nice however I wonder how it works in real scene - with
radosity, more light_sources, fog, media, etc. Does applying of your grass
require complete rewrite of scene or just replacement of one type of grass with
another (and everything is 3d) ?

ABX

Post a reply to this message

"John Robinson" wrote:
> i think your faked grass sure has a more
> natural feel to it.

Thanks!

> how does the grass look from kind of close up?

Not good I'm afraid, since it's not shaded or anything. I'll post an image
of this in a little while.

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

Post a reply to this message

The top image looked like somebody mowed it- and that has definite uses, so
this is not a bad thing.  The bottom looks more "wild" or natural.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip

Post a reply to this message

> Your grass is very nice however I wonder how it
> works in real scene - with radosity, more
> light_sources, fog, media, etc. Does applying of
> your grass require complete rewrite of scene or
> just replacement of one type of grass with another
> (and everything is 3d) ?

Multiple light_sources and radiosity shouldn't be a problem, but you the
grass is not correctly shaded in the first place. It's just a texture, so
the normal points upwards, not to all the sides like it would on real grass.
In certain lighting situations the grass will look all wrong, but in normal
daylight it should be fine.

Similarly, fog, media etc. should not be a problem, and a major rewrite
shouldn't be required. The ground that the grass is on is 3d, but the blades
of grass are not.

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

Post a reply to this message

"Rune" <run### [at] mobilixnetdk> wrote in message
news:3cab1d7b@news.povray.org...
> "John Robinson" wrote:
> > i think your faked grass sure has a more
> > natural feel to it.
>
> Thanks!
>
> > how does the grass look from kind of close up?
>
> Not good I'm afraid, since it's not shaded or anything. I'll post an image
> of this in a little while.
>

a little focal blur could be my solution

john


> 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
>
>

Post a reply to this message

> Ok, I really don't know what to conclude, so I'll just let it be up to
> you...
>
> Rune




Before I can judge about parsing time, I want to know how many grass blades
you have used with the mesh grass. It does not look as fine as with your
fast grass macro.

Norbert

Post a reply to this message

> Your grass is very nice however I wonder how it works in real scene - with
> radosity, more light_sources, fog, media, etc. Does applying of your grass
> require complete rewrite of scene or just replacement of one type of grass
with
> another (and everything is 3d) ?
>
> ABX


for yourself. There are some drawbacks but overall it is a good effect
(perhaps it is also useful as fur texture?).
If I would have used mesh grass, 1 GB peak memory would not have been enough
because of the large area.
In my scene there is no radiosity, but photons worked as "global
illumination". The scene uses fog and absorbing media too. And as Rune
stated, it is "only" a texture.

Norbert

Post a reply to this message

Rune <run### [at] mobilixnetdk> wrote in message
>
> Ok, I really don't know what to conclude, so I'll just let it be up to
> you...
>

I believe that each has it's place. Your macro is a very powerful tool which
will be more effective than mesh grass in many instances. Perhaps for closer
shots, a combination of the two techniques would work well. Mesh grass could
be used to give a distinct blade shape, and your grass could be used to add
density.

 -Shay

Post a reply to this message