wouldn't distance-dependent grass be better on render times?  like if
the quality stuff was up front, then not so good, but faster, ending
with a regular texture far out?  is there a not-so-good grass macro?  or
are they all made for close up inspection?  i've seen trees that are
supposed to be used far away, but not grass.

for the current image, how high up are you from the grass and what is
the length of the grass?  oh, and how far out does it go? (just trying
to get a perspective here)  also, is it one patch of grass or several? 
is it possible to selectively smash down certain areas of the grass;
like alien landing sites in crops or the shape an animal makes when it
lays down?  and what are the units you use?  can you make the light and
dark areas (wind?) more smooth or are you stuck with what you get? 
thanks.

Mick Hazelgrove wrote:
> 
> Yep, my next project - I want to create some rocks based on samuals basalt
> columns and about 2 million blades of grass on a HF using your mod and some
> of mine on Samuals code. Then I'll throw in some media, a few rocks and
> radiosity and go on holiday for a month!!!!!
> 
> Mick
> 
> "Tony[B]" <ben### [at] panamac-comnet> wrote in message
> news:39574eda@news.povray.org...
> > Does this use the source I sent you? Looks nice. I wonder what this would
> > look like on a far away hill? (Maybe you should borrow some RAM from a
> > couple friends, and give a full scene a try. :)
> >
> >

Post a reply to this message

On Mon, 26 Jun 2000 19:01:42 +0100, "Mick Hazelgrove"
<mic### [at] mhazelgrovefsnetcouk> wrote:

>> Wow Mick... I haven't even tried that many yet.... I guess the grass isn't
>> so fast when so many are used :) I wonder if making one smaller square of
>> grass and then copying it would save memory? You'd have to make sure nobody
>> could see the repetitions.

>That's the usual technique but you'd loose the advantage of eval_pigment.

Not if you use a tileable pigment made with Chris' macro :)
 I
>don't think youd save much memory either. As most of the parsing time was
>spent on creating bounding slabs, I guess that manual bounding is the way to
>go when I work out how to do it!

A quadtree hierarchy of bounding boxes would be a good shot at it, I
guess.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] usanet
TAG      e-mail : pet### [at] tagpovrayorg

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Its Samual's grass macro but spacing between grass blades has been reduced
from 1 to .01pov units!!!!

Mick

"ryan constantine" <rco### [at] yahoocom> wrote in message
news:3957B67A.EEACDBD2@yahoo.com...
> wouldn't distance-dependent grass be better on render times?  like if
> the quality stuff was up front, then not so good, but faster, ending
> with a regular texture far out?  is there a not-so-good grass macro?  or
> are they all made for close up inspection?  i've seen trees that are
> supposed to be used far away, but not grass.
>
> for the current image, how high up are you from the grass and what is
> the length of the grass?  oh, and how far out does it go? (just trying
> to get a perspective here)  also, is it one patch of grass or several?
> is it possible to selectively smash down certain areas of the grass;
> like alien landing sites in crops or the shape an animal makes when it
> lays down?  and what are the units you use?  can you make the light and
> dark areas (wind?) more smooth or are you stuck with what you get?
> thanks.
>
> Mick Hazelgrove wrote:
> >
> > Yep, my next project - I want to create some rocks based on samuals
basalt
> > columns and about 2 million blades of grass on a HF using your mod and
some
> > of mine on Samuals code. Then I'll throw in some media, a few rocks and
> > radiosity and go on holiday for a month!!!!!
> >
> > Mick
> >
> > "Tony[B]" <ben### [at] panamac-comnet> wrote in message
> > news:39574eda@news.povray.org...
> > > Does this use the source I sent you? Looks nice. I wonder what this
would
> > > look like on a far away hill? (Maybe you should borrow some RAM from a
> > > couple friends, and give a full scene a try. :)
> > >
> > >

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Care to explain in english!!!!

"Peter Popov" <pet### [at] usanet> wrote in message
news:4lfflso0j3b8m93i4e3oqu3j426l8dmcpb@4ax.com...
> On Mon, 26 Jun 2000 19:01:42 +0100, "Mick Hazelgrove"
> <mic### [at] mhazelgrovefsnetcouk> wrote:
>
> >> Wow Mick... I haven't even tried that many yet.... I guess the grass
isn't
> >> so fast when so many are used :) I wonder if making one smaller square
of
> >> grass and then copying it would save memory? You'd have to make sure
nobody
> >> could see the repetitions.
>
> >That's the usual technique but you'd loose the advantage of eval_pigment.
>
> Not if you use a tileable pigment made with Chris' macro :)
>  I
> >don't think youd save much memory either. As most of the parsing time was
> >spent on creating bounding slabs, I guess that manual bounding is the way
to
> >go when I work out how to do it!
>
> A quadtree hierarchy of bounding boxes would be a good shot at it, I
> guess.
>
>
> Peter Popov ICQ : 15002700
> Personal e-mail : pet### [at] usanet
> TAG      e-mail : pet### [at] tagpovrayorg

Post a reply to this message

On Mon, 26 Jun 2000 22:05:15 +0100, "Mick Hazelgrove"
<mic### [at] mhazelgrovefsnetcouk> wrote:

>Care to explain in english!!!!

About the tileable pigment, Chris Colefax has a macro that would make
any texture tile seemlessly. Granted, a repetition *may* be noticed
but the probability would not be as high.

Now about the bounding quadtree. Imagine you have a big (and
relatively flat) grass patch consisting of, say, 32x32 smaller patches
whose bounds you know. Bound each patch into its own bounding box. You
now have 32x32 bounding boxes. Bow bound them in quads, 2x2 so that
you have 8x8 bounding boxes each of which has 2x2 bounded patches in
it. Then do this again so that you have 4x4 larger bounds, then again
to get 2x2 and finally bound them into a single box.

Why would you want to do that?

Imagine a ray-shape intersection test. A ray is shot from the camera.
If no bounding is used, it would have to be tested against each of the
32x32=1024 patches (consider them single objects for simplicity). With
a hierarchical bounding scheme such as the one described above, the
ray will first be tested against the outermost box, then if there's an
intersection it will be tested against the inner four and so on and
the test will traverse down the quadtree (quad because each 'branch'
has four sub-branches) and only follow those branches which are likely
to result in an actual intersection.

The best results would be achieved if the grass field is viewed from
above because the projections of the bounding boxes on the screen (the
vista buffers) would not overlap. I am sure a more efficient method
can be developed which would incorporate adaptive median subdivision
of the bounding boxes combined with minimizing the vista buffer
overlapping but I would probably leave this for povray.programming or
povray.unofficial.patches ;)

Hope it helps any.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] usanet
TAG      e-mail : pet### [at] tagpovrayorg

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In article <3957B67A.EEACDBD2@yahoo.com>, ryan constantine 
<rco### [at] yahoocom> wrote:

> is it possible to selectively smash down certain areas of the grass;
> like alien landing sites in crops or the shape an animal makes when it
> lays down?

Another possible use for the eval_*() functions...

-- 
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/

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BTW, I tried to do some tests of my own using 50,000 blades, and after 3
hours and a half of parsing, the machine gave me an out of memory message.
:-/ How do you do it? I only got as far as "Creating bounding slabs..."

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Time to kick off the shoes and run barefoot.
That render-time says "no animation, nuh-uh".

Bob

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Mick Hazelgrove wrote:
> 
> There are 400005 blades of grass in this pic - took 5 hrs to render - 3hrs
> 45 mins to parse!
> 
> Mick
> 

Hmm, I counted only 399968 blades, seems like someone were left out of
frame...
Additionally I don't think that this picture will qualify as excellent
example of lawn: grass is in clumps and too long, seems like it hasn't
been rolled (??) couple of hundred years yet...
<j/k, pulling long face from envy.>

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Suggest:
A white picket fence,
A cute little house,,
And something to do w/ children ( a swing set w/ swirly colors on the metal
or a nice wooden one),,,

Mick Hazelgrove wrote:

> There are 400005 blades of grass in this pic - took 5 hrs to render - 3hrs
> 45 mins to parse!
>
> Mick
>
>  [Image]

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