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Compare 3 images make with
hdri from terragen and HdrShop,
render in
pov 3.5, Megapov1 and Mlpov
http://cathemline.org/testehdr/cmp.html
Happy new Year!
___________
Martial
http://Cathemline.org
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> Compare 3 images
Hi,
Well, it's not too easy to compare them without further explanation. You
have changed some settings between the renders. Is that an attempt to get 3
similar results? If so, you can do better. :o) But if the purpose is
solely to test the response to light between the POV versions, I'd like to
know more about, why you had to change some settings.. And why is the
right-most ball much brighter in the official Pov3.5? That makes no sense to
me.
Have I been sleepy or is there a "version 1" of MegaPOV, because the last
one was version 0.7 to me knowledge.
Can we assume that your sky from Terragen has a realistic fading; i.e. not
too strong contrast between sun-position and opposite position? Because I
still doubt that there is any benefit in using the HDR format with a sky
picture.
Thanks for your post,
Hugo
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"Hugo Asm"
> Well, it's not too easy to compare them without further explanation. You
> have changed some settings between the renders.
Yes :
In pov 3.5
recursion limite 1
brigtness 10
the ambient of the SkySphere to 1.3
the material of the 1er sphere to right pigment{rgb .2 }
In Megapov1 (download here http://megapov.inetart.net/)
exposure 0.3 exposure_gain 12
recursion limite 1
brigtness 1
the ambient of the SkySphere to 1.0
the material of the 1er sphere to right pigment{rgb 1}
In Mlpov
recursion limite 1
brigtness 1
the ambient of the SkySphere to 5
the material of the 1er sphere to right pigment{rgb 0.8}
> Have I been sleepy or is there a "version 1" of MegaPOV, because the last
> one was version 0.7 to me knowledge.
Yes your sleep, It's new :)
(download here http://megapov.inetart.net/)
> Can we assume that your sky from Terragen has a realistic fading; i.e. not
> too strong contrast between sun-position and opposite position? Because I
> still doubt that there is any benefit in using the HDR format with a sky
> picture.
Yes sure.......heu ...... I make a rapid image... for rapid teste.
--
Martial
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3e11d426@news.povray.org...
> Compare 3 images make with
> hdri from terragen and HdrShop,
> render in
> pov 3.5, Megapov1 and Mlpov
> http://cathemline.org/testehdr/cmp.html
Interesting ! I've been running tests with Terragen too with similar results
(more contrast in the sky image) though I still have to be sure that
identical results cannot be obtained by using a slightly corrected (gamma or
tone) regular map.
Note that there's a plugin for Terragen that creates directly HDR files from
Terragen (unlike you I wasn't patient enough to do it with different
exposure values !)
http://www.geocities.com/ffrog.geo/sopack.html
> Happy new Year!
Gilles
--
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters
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3e11d9a8$1@news.povray.org...
> Can we assume that your sky from Terragen has a realistic fading; i.e. not
> too strong contrast between sun-position and opposite position? Because I
> still doubt that there is any benefit in using the HDR format with a sky
> picture.
One interesting thing is to look at the color numbers displayed at the
bottom of HDRShop. In the case of Martial's HDR map, the
values are comprised in a narrow and low range (between rgb 0.1 and 0.45),
so in fact no real HDR effect can be expected.
Using the HDR export plugin for Terragen, I obtained a much larger range in
a sunset image, from rgb 0.3 to 166 (on the sun itself), similar to the one
observed in actual HDR probes. Of course these numbers are relative but
playing with the exposure feature in HDRShop allows to see what the image
can reveal. For instance, the HDR park map I used on the Parrott's folly pic
has a range going from rgb 1 to 5 in the "white sky" part, which means that
it's much more directional than the corresponding low range image would
suggest, which is rgb 1 for all the sky parts. The brightest spot is
actually just above the trees. So it's there... which doesn't mean that the
contribution is visually significant !
G.
--
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters
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> Using the HDR export plugin for Terragen, I obtained a much larger range
in
> a sunset image, from rgb 0.3 to 166 (on the sun itself), similar to the
one
> observed in actual HDR probes.
povray radiosity is not very well suited to handle such situations with
small bright area, as it samples rays evenly in all directions. It would be
more efficient to send more rays toward the high intensity areas (the sun
here). In the case of image lighting we know where those zones are so there
is probably room for algorithm improvement..
and for your white sky you need the expose patch from megapov 1.0 :)
M
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The link to the HDR file at that site is broken. Please fix..
"Martial" <mar### [at] pov-monde org> wrote in message
news:3e11d426@news.povray.org...
> Compare 3 images make with
> hdri from terragen and HdrShop,
> render in
> pov 3.5, Megapov1 and Mlpov
> http://cathemline.org/testehdr/cmp.html
>
> Happy new Year!
> ___________
> Martial
> http://Cathemline.org
>
>
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"Michael Goldshteyn
> The link to the HDR file at that site is broken. Please fix..
Oops !
corected !
___________
Martial
http://Cathemline.org
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3e1398be@news.povray.org...
> povray radiosity is not very well suited to handle such situations with
> small bright area, as it samples rays evenly in all directions. I
Yes, that should explains some of the problems with HDR maps with many small
hot spots. For sun/sky situations it's less of a issue because the hot spot
can be much larger even though I've observed some weird artefacts with
Terragen HDRs.
>It would be more efficient to send more rays toward the high intensity
areas (the sun
> here). In the case of image lighting we know where those zones are so
there
> is probably room for algorithm improvement..
Every improvement in image lighting has my blessing :-)
G.
--
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters
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