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I do astronomical renders all the time (well I am an astronomy lecturer!)...
I simply choose a better base unit... Megametres, Gigametres or even AUs
instead of kilometres.
1 AU = 149597870.691km
= 149597.870691Mm
= 149.597870691Gm
Even Sedna's orbit is now only 75-975 AU or 11219.7-145857Gm... The only
slight problem there is that Sedna is only 0.0015Gm across!
One of these days I'm going to finish my SolarSystem toolkit include file!
Rarius
"Nekar Xenos" <nek### [at] gmail com> wrote in message
news:47e8ce0b@news.povray.org...
>
> news:47e7f1fc$1@news.povray.org...
>> High!
>>
>> Once more with my long-cherished Solar System project... originally I
>> equalled 1 POV unit = 1 km - which pretty soon turned out to be
>> unfeasible, as the Sun is several times farther even from Mercury than
>> PoV-Ray's epsilon value would allow it to be rendered correctly, let
>> alone the other celestial bodies in the Solar System.
>>
>> So I introduced a scale value, based on the aphelion (furthest point of
>> orbit from the Sun) of trans-Kuiper Belt object Sedna, and adjusted it
>> dynamically to the distance between camera and the Sun (or any other
>> body):
>>
>
> I hope future versions of Pov-Ray will fix this problem. A lot of Povers
> love doing astronomical stuff =)
>
>
> --
> -Nekar Xenos-
>
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If you're going to be combining nearby objects (such as a spaceship) and
astronomical objects (such as Sedna) in the same scene, you may need to
break the scaling.
You can split the scene into things that are nearby and things that are
far away. Then you can use the fact that an object of diameter 1800km at
a distance of 145900000000km looks almost exactly the same as an object
of diameter 1.8m at a distance of 145900km. So dividing the distances
and sizes of all the far away objects by a million makes no difference
to the render.
--
Mike Williams
Gentleman of Leisure
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Warp escribió:
> Nicolas Alvarez <nic### [at] gmailisthebestcom> wrote:
>> Hmm... Looks like there are some C++ wrappers around MPFR that would
>> make it quite simpler. And when I say simpler, I mean that in many
>> cases, replacing 'double' with 'mpfr_class' would be all (who said
>> operator overloading was bad?)
>
> There may be wrappers, but are they efficient?
Using MPFR wouldn't be efficient in the first place (compared to plain
old doubles), so...
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Nicolas Alvarez <nic### [at] gmailisthebestcom> wrote:
> > Nicolas Alvarez <nic### [at] gmailisthebestcom> wrote:
> >> Hmm... Looks like there are some C++ wrappers around MPFR that would
> >> make it quite simpler. And when I say simpler, I mean that in many
> >> cases, replacing 'double' with 'mpfr_class' would be all (who said
> >> operator overloading was bad?)
> >
> > There may be wrappers, but are they efficient?
> Using MPFR wouldn't be efficient in the first place (compared to plain
> old doubles), so...
That's not really what I asked.
--
- Warp
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From: Sherry Shaw
Subject: Re: Lighting problem at extreme distances
Date: 26 Mar 2008 07:51:22
Message: <47ea46ca@news.povray.org>
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Mike Williams wrote:
> If you're going to be combining nearby objects (such as a spaceship) and
> astronomical objects (such as Sedna) in the same scene, you may need to
> break the scaling.
>
I wonder if it might be possible to break the scaling in such a way as
to have one's cake and eat it too...? What just occurred to me was the
sample "Desk" scene, which is rendered as a three-frame animation in
order to create a recursive image in the photo on the desk. For example:
Write the scene as a two-frame animation. When frame_number = 0, render
only the very distant objects, with one POV unit = a very big number.
When frame_number = 1, render the closer objects with one POV unit = a
smaller number; use the output from the first frame as an image_map
applied to a plane or box in the background of the second frame.
By putting actual, legitimate scaling factors into your code, you can
therefore argue that you haven't "broken" the scale at all, but merely
dragged it, kicking and screaming, into the real world.
I think this would work, but I've just barely finished my first cup of
coffee... ;)
--Sherry Shaw
--
#macro T(E,N)sphere{x,.4rotate z*E*60translate y*N pigment{wrinkles scale
.3}finish{ambient 1}}#end#local I=0;#while(I<5)T(I,1)T(1-I,-1)#local I=I+
1;#end camera{location-5*z}plane{z,37 pigment{granite color_map{[.7rgb 0]
[1rgb 1]}}finish{ambient 2}}// TenMoons
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Sherry Shaw wrote:
> Mike Williams wrote:
>> If you're going to be combining nearby objects (such as a spaceship)
>> and astronomical objects (such as Sedna) in the same scene, you may
>> need to break the scaling.
>>
>
> I wonder if it might be possible to break the scaling in such a way as
> to have one's cake and eat it too...? What just occurred to me was the
> sample "Desk" scene, which is rendered as a three-frame animation in
> order to create a recursive image in the photo on the desk. For example:
>
> Write the scene as a two-frame animation. When frame_number = 0, render
> only the very distant objects, with one POV unit = a very big number.
> When frame_number = 1, render the closer objects with one POV unit = a
> smaller number; use the output from the first frame as an image_map
> applied to a plane or box in the background of the second frame.
>
> By putting actual, legitimate scaling factors into your code, you can
> therefore argue that you haven't "broken" the scale at all, but merely
> dragged it, kicking and screaming, into the real world.
>
> I think this would work, but I've just barely finished my first cup of
> coffee... ;)
>
> --Sherry Shaw
>
>
I agree, Sherry. IIRC I posted an image here a few years ago using the
same technique. Mine was a monitor showing a monitor showing a monitor
etc etc.
BTW How was the coffee?
John
--
I will be brief but not nearly so brief as Salvador Dali, who gave the
world's shortest speech. He said, "I will be so brief I am already
finished," then he sat down.
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> I agree, Sherry. IIRC I posted an image here a few years ago using the
> same technique. Mine was a monitor showing a monitor showing a monitor
> etc etc.
http://www.infinitecat.com/
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"Nicolas Alvarez" <nic### [at] gmailisthebestcom> schreef in bericht
news:47eaadbe$1@news.povray.org...
>
> http://www.infinitecat.com/
LOL
Thomas
[from a cat lover]
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From: Sherry Shaw
Subject: Re: Lighting problem at extreme distances
Date: 27 Mar 2008 21:24:52
Message: <47EC56CC.9080508@aol.com>
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Doctor John wrote:
> BTW How was the coffee?
(Heavy sigh) Instant.
--Sherry Shaw
--
#macro T(E,N)sphere{x,.4rotate z*E*60translate y*N pigment{wrinkles scale
.3}finish{ambient 1}}#end#local I=0;#while(I<5)T(I,1)T(1-I,-1)#local I=I+
1;#end camera{location-5*z}plane{z,37 pigment{granite color_map{[.7rgb 0]
[1rgb 1]}}finish{ambient 2}}// TenMoons
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From: Sherry Shaw
Subject: Re: Lighting problem at extreme distances
Date: 27 Mar 2008 21:27:34
Message: <47ec5796@news.povray.org>
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Nicolas Alvarez wrote:
> http://www.infinitecat.com/
OMG, LOL!
Possum, Patches, and Lord Greyfluffy express their appreciation.
--Sherry Shaw
--
#macro T(E,N)sphere{x,.4rotate z*E*60translate y*N pigment{wrinkles scale
.3}finish{ambient 1}}#end#local I=0;#while(I<5)T(I,1)T(1-I,-1)#local I=I+
1;#end camera{location-5*z}plane{z,37 pigment{granite color_map{[.7rgb 0]
[1rgb 1]}}finish{ambient 2}}// TenMoons
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