My favorite time of day is when the sun hangs low on the horizon and casts
long rays of warm yellow light on the landscape.  This is just an effort to
recapture that feeling on a cloudy Sunday.

The bridge is made of superellipsoids, the trees are from POVTree (and
aren't my favorite trees--I'll try something different next time I render
this), and the landscape is made from isosurfaces, of course.

I used an area light but I'm left with grainy shadows.  Could someone tell
me how to avoid that?

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On Sun, 25 Mar 2007 19:42:23 EST, "Kirk Andrews"
<kir### [at] hotmailcom> wrote:

>My favorite time of day is when the sun hangs low on the horizon and casts
>long rays of warm yellow light on the landscape.  This is just an effort to
>recapture that feeling on a cloudy Sunday.
>
>The bridge is made of superellipsoids, the trees are from POVTree (and
>aren't my favorite trees--I'll try something different next time I render
>this), and the landscape is made from isosurfaces, of course.
>
>I used an area light but I'm left with grainy shadows.  Could someone tell
>me how to avoid that?

I cannot help with your question but one comment.  The road / path to
get on the bridge should be a much more gentle slope and not just
follow the arch shape. It would be almost impossible to get onto this
bridge.

John Cranmer

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John <joh### [at] worldcom> wrote:
> On Sun, 25 Mar 2007 19:42:23 EST, "Kirk Andrews"
>
> I cannot help with your question but one comment.  The road / path to
> get on the bridge should be a much more gentle slope and not just
> follow the arch shape. It would be almost impossible to get onto this
> bridge.
>
> John Cranmer

You're quite right!  I'll have to adjust that.

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"Kirk Andrews" <kir### [at] hotmailcom> schreef in bericht 
news:web.460716efcc3df6852577d2d70@news.povray.org...
>
> I used an area light but I'm left with grainy shadows.  Could someone tell
> me how to avoid that?
>

Maybe the area_light should be smaller? From Cousin Ricky, I learned the 
following trick for sun light:

#declare SunPosition = <vector>;
#declare SunDis = vlength(SunPosition)*2/215;

light_source{
    SunPosition
    color rgb 1.0    //or whatever color you want to use
    area_light
    SunDis*x, SunDis*z, // lights spread out across this distance (x * z)
    3, 3                // total number of lights in grid (4x*4z = 16 
lights)
    adaptive 1          // 0,1,2,3...
    jitter              // adds random softening of light
    circular            // make the shape of the light circular
    orient              // orient light
}

Maybe that helps....

Thomas

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Kirk Andrews nous apporta ses lumieres en ce 25-03-2007 20:42:
> My favorite time of day is when the sun hangs low on the horizon and casts
> long rays of warm yellow light on the landscape.  This is just an effort to
> recapture that feeling on a cloudy Sunday.
> 
> The bridge is made of superellipsoids, the trees are from POVTree (and
> aren't my favorite trees--I'll try something different next time I render
> this), and the landscape is made from isosurfaces, of course.
> 
> I used an area light but I'm left with grainy shadows.  Could someone tell
> me how to avoid that?
> 
> 
> ------------------------------------------------------------------------
> 
How many elements in your area_light? The default of 4?
That grainyness is caused by a sparce array coupled with jitter. With jitter, 
the elements of the area_light move around from pixel to pixel, and that 
movement is proportional to the spacing between the various elements. If the 
light is 100*100 unit and is composed of 4*4 elements, they can move about 20 
unit around ther base locations.

Best way is to use a much denser array and use adaptive with as small a value as 
you can get by. With adaptive, it's best to use values like 9, 17, 33, 65,... 
(the powers of 2 plus 1). Start with adaptive 0 (minimum array of 3*3 to be 
helpfull), use adaptive 1 (array at least 5*5) if you get artefacts, up that to 
2 if 1 in still not enough (array at least 9*9). That way, you get nice, smooth 
shading and reasonable rendering speed.

Adaptive 0 start with the 4 corners and, if some are not visible, samples half 
way between them, forming 4 smaler squares. If a square is completely visible, 
or not visible, no more subsampling is done. If there is a fifference, the 
subsampling is repeated, limited with the size of the array.

-- 
Alain
-------------------------------------------------
   A hooker once told me she had a headache.
   	Rodney Dangerfield

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