> Maybe you are taking photorealism too far. If it's to blurry,
> why don't you just reduce the blur? Just think of the number
> of blur_samples you'll need to make this look good anyway ;)

On a similar note, when I first looked at the image, I thought "That 
shadow needs an area light!" Then I realized that I've spent so much 
time indoors with fluorescent light that shadows from sunlight look 
wrong to me. >_<

-- 
William Tracy
afi### [at] gmailcom -- wtr### [at] calpolyedu

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William Tracy wrote:

> On a similar note, when I first looked at the image, I thought "That 
> shadow needs an area light!" Then I realized that I've spent so much 
> time indoors with fluorescent light that shadows from sunlight look 
> wrong to me.

Actually, the sun appears as a disk, not as a point light, so
a circular area light would be quite appropriate. But who knows,
maybe the final version will use a sky dome, the HDRI is there ;)

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> Actually, the sun appears as a disk, not as a point light, so
> a circular area light would be quite appropriate. But who knows,
> maybe the final version will use a sky dome, the HDRI is there ;)

But the sun is so far away that it still generates pretty sharp shadows 
(compared to indoor lighting).

-- 
William Tracy
afi### [at] gmailcom -- wtr### [at] calpolyedu

You know you've been raytracing too long when you are certain that if 
you see one more post on c.g.r.r. from a newbie asking what the best 
raytracing software available is you're going to go out and throttle the 
hell out of someone just to get it out of your system.
Ken Tyler

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Well real cameras have adjustable apertures, a photo taken outdoors in 
fairly bright sunlight would not usually have the aperture open far enough 
for this much blur, though it is possible with a filter. I just wanted to 
get an upper limit for maximum possible blur within the bounds of reality. 
Since it's more blur than I need I'm safely inside the bounds of reality 
with whatever setting I choose!

-- 
Tek
http://evilsuperbrain.com

"Christian Froeschlin" <chr### [at] chrfrde> wrote in message 
news:46215631$1@news.povray.org...
> Tek wrote:
>
>> But I think it's too blurry, so I'm gonna build some background objects.
>
> Maybe you are taking photorealism too far. If it's to blurry,
> why don't you just reduce the blur? Just think of the number
> of blur_samples you'll need to make this look good anyway ;)
>
> I suppose camera manufacturers would happily build cameras which show
> less blur if they could (well, in fact you can take multiple images
> with different focus and combine them in software).

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Apparently, according to wikipedia, the sun's disk has a diameter of around 
0.5 degrees from our point of view. That's equivalent to an area light at a 
distance of 1 unit having a width of 0.0087 units, which is really not very 
much blur. I'm using about 3 times more area_light blur than is realistic.

-- 
Tek
http://evilsuperbrain.com

"William Tracy" <wtr### [at] calpolyedu> wrote in message 
news:46217c76@news.povray.org...
>> Actually, the sun appears as a disk, not as a point light, so
>> a circular area light would be quite appropriate. But who knows,
>> maybe the final version will use a sky dome, the HDRI is there ;)
>
> But the sun is so far away that it still generates pretty sharp shadows 
> (compared to indoor lighting).
>
> -- 
> William Tracy
> afi### [at] gmailcom -- wtr### [at] calpolyedu
>
> You know you've been raytracing too long when you are certain that if you 
> see one more post on c.g.r.r. from a newbie asking what the best 
> raytracing software available is you're going to go out and throttle the 
> hell out of someone just to get it out of your system.
> Ken Tyler

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Tek wrote:
> Apparently, according to wikipedia, the sun's disk has a diameter of around 
> 0.5 degrees from our point of view. 

Except that back-scattering off the atmosphere provides a much larger 
area of light. Contrast the sky with the moon vs the sun, both of which 
are about the same size. It's difficult to even look close to the sun on 
a clear day.

-- 
   Darren New / San Diego, CA, USA (PST)
     His kernel fu is strong.
     He studied at the Shao Linux Temple.

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The reason it's hard to look at the sun is it's brighter than the moon. 
Nonetheless with the right filter you can clearly see the sun's disk, which 
means the disk itself is significantly brighter than light scattered by the 
atmosphere. So I'll use an area light for the disc, and the radiosity from 
my HDR dome will handle the light from the sky.

-- 
Tek
http://evilsuperbrain.com

"Darren New" <dne### [at] sanrrcom> wrote in message 
news:4621a037$1@news.povray.org...
> Tek wrote:
>> Apparently, according to wikipedia, the sun's disk has a diameter of 
>> around 0.5 degrees from our point of view.
>
> Except that back-scattering off the atmosphere provides a much larger area 
> of light. Contrast the sky with the moon vs the sun, both of which are 
> about the same size. It's difficult to even look close to the sun on a 
> clear day.
>
> -- 
>   Darren New / San Diego, CA, USA (PST)
>     His kernel fu is strong.
>     He studied at the Shao Linux Temple.

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Among other things, Darren New saw fit to write:

> Except that back-scattering off the atmosphere provides a much larger
> area of light. Contrast the sky with the moon vs the sun, both of which
> are about the same size. It's difficult to even look close to the sun on
> a clear day.

So similar are their sizes, indeed, that we can experience both total and
anular eclipses... I find that amazing.

-- 
light_source{9+9*x,1}camera{orthographic look_at(1-y)/4angle 30location
9/4-z*4}light_source{-9*z,1}union{box{.9-z.1+x clipped_by{plane{2+y-4*x
0}}}box{z-y-.1.1+z}box{-.1.1+x}box{.1z-.1}pigment{rgb<.8.2,1>}}//Jellby

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Tek wrote:
> The reason it's hard to look at the sun is it's brighter than the moon. 

Right. I meant, it's difficult to even look within about 5 degrees of 
the sun. I think the disk that's projecting light is a lot larger than 
0.5%. Of course, in POV you have to do things somewhat differently to 
get the same effect.

-- 
   Darren New / San Diego, CA, USA (PST)
     His kernel fu is strong.
     He studied at the Shao Linux Temple.

Post a reply to this message

"Darren New" <dne### [at] sanrrcom> wrote in message 
news:46225066$1@news.povray.org...
> Tek wrote:
>> The reason it's hard to look at the sun is it's brighter than the moon.
>
> Right. I meant, it's difficult to even look within about 5 degrees of the 
> sun. I think the disk that's projecting light is a lot larger than 0.5%. 
> Of course, in POV you have to do things somewhat differently to get the 
> same effect.

I'm not sure I follow. The sun's disk is 5 degrees in radius from earth, the 
brightness of it doesn't make it any larger (like I say you can use a filter 
to see that all the suns direct light comes from that disk). Povray can 
simulate a circular area light of the same angle and brightness. The only 
reason I'm using a larger one is because I'm taking some artistic license, 
in truth a small ball on a table would have an almost perfectly sharp 
shadow.

-- 
Tek
http://evilsuperbrain.com

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