Hi Ron

There seems to be a strange relationship between the distance the camera is
from the hf and the size of the bounding box.
If the distance is too small the top of the hf is cut off. scaling also
produces some strange effects if it is not correct the hf disappears can you
throw any light on this.

Mick

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Mick Hazelgrove heeft geschreven in bericht <3786f5cd@news.povray.org>...
>Hi Ron
>
>There seems to be a strange relationship between the distance the camera is
>from the hf and the size of the bounding box.
>If the distance is too small the top of the hf is cut off.

changing the camera angle (by 0.1) and changing scale*y (by 0.01) can have the
same result.

>scaling also produces some strange effects if it is not correct the hf
>disappears can you throw any light on this.


ingo

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I've been investigating this problem a little more because I could not reproduce
it with several bitmaps.
After doing all kinds of stuff I finally did the following:
Made a tga (256x256) all white and renderd it, the result is a 1 unit box. Next
I added a black border all around. Renderd it again, and the top of the box is
chopped off. Next I added one single white pixel to the top right corner. This
bitmap renders ok (one unit box).
(The full black border is 3 pixels wide. If the border is only one pixel wide,
it runs ok with "interpolate 2" but not with no interpolation.)

Then I took Mikes picture, added one white pixel to the upper right corner and
all seems to be ok. Made the corner black and an other pixel on the border
white, the problem is back again.
It seems the bitmap is of influence on the problem. Scene file available if
needed.

ingo

--
Met dank aan de muze met het glazen oog.

ingo heeft geschreven in bericht <37871cfa@news.povray.org>...
>Mick Hazelgrove heeft geschreven in bericht <3786f5cd@news.povray.org>...
>>Hi Ron
>>
>>There seems to be a strange relationship between the distance the camera is
>>from the hf and the size of the bounding box.
>>If the distance is too small the top of the hf is cut off.
>
>changing the camera angle (by 0.1) and changing scale*y (by 0.01) can have the
>same result.
>
>>scaling also produces some strange effects if it is not correct the hf
>>disappears can you throw any light on this.
>
>
>ingo

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ingo heeft geschreven in bericht <378a402f@news.povray.org>...
>.....Next I added one single white pixel to the top right corner. This
>bitmap renders ok (one unit box).
>......
>Then I took Mikes picture, added one white pixel to the upper right corner and
>all seems to be ok. ........

Aaarghh,
In both cases it is the top left corner that makes it all work.

....and it is Micks picture, not Mikes

ingo

--
Met dank aan de muze met het glazen oog.

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On Mon, 12 Jul 1999 21:30:56 +0200, ingo wrote:
>
>ingo heeft geschreven in bericht <378a402f@news.povray.org>...
>>.....Next I added one single white pixel to the top right corner. This
>>bitmap renders ok (one unit box).
>>......
>>Then I took Mikes picture, added one white pixel to the upper right corner and
>>all seems to be ok. ........
>
>Aaarghh,
>In both cases it is the top left corner that makes it all work.
>
>....and it is Micks picture, not Mikes
>
>ingo

What happens if you play with the max gradient and such?  The isosurface
you're rendering has a very large gradient at the surface (approximately 
equal to the resolution of the image) which would probably not respond 
well to a simple 'eval'.

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>What happens if you play with the max gradient and such?  The isosurface
>you're rendering has a very large gradient at the surface (approximately
>equal to the resolution of the image) which would probably not respond
>well to a simple 'eval'.

That does it,
Mick's terrain looks to be ok with a max_gradient 20.
The box needs a much higher setting, about 100.

thanks Ron

ingo
--
Met dank aan de muze met het glazen oog.

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