 |
|
|
|
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Hi,
I've discovered a problem with very large spheres seeming to vanish
above a certain size. This fisrt showed itself when I was trying
to use randomly placed spheres to create a starfield: when I moved
the spheres further away from the camera (and made them larger) they
vanished.
I've seen this problem under Win 98 using POVRay 3.5 beta 8. I've
created
a small scene file and .ini file to demonstrate the problem. This
creates
an animation of a radius 1 sphere being scaled by values between 0 and
4,000,000 (the camera's at the origin, and the sphere is a few units
away). The sphere /should/ stay the same size, but at around
scale 2,800,000 it shrinks away, and vanishes.
This problem only seems to occur with evenly scaled spheres - I've tried
it with boxes and unevenly scaled spheres, and they're OK.
I'll post the .pov and .ini files to povray.beta-test.binaries
Thanks,
Alun.
Post a reply to this message
|
|
| |
| |
|
|
From: Thorsten Froehlich
Subject: Re: Disappearing Large Sphere Bug in beta 8
Date: 2 Dec 2001 07:27:54
Message: <3c0a1e4a@news.povray.org>
|
|
|
| |
| |
|
|
In article <3C095E20.C3FF6972@lineone.net> , James Hansen
<jam### [at] lineone net> wrote:
> I've discovered a problem with very large spheres seeming to vanish
> above a certain size. This fisrt showed itself when I was trying
> to use randomly placed spheres to create a starfield: when I moved
> the spheres further away from the camera (and made them larger) they
> vanished.
Not a bug. Your sphere simply grows out of the the space POV-Ray considers
for intersection. It is similar to:
<http://www.students.tut.fi/~warp/povVFAQ/misconceptions.html#simulatingsun>
Thorsten
____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg
I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Thorsten Froehlich <tho### [at] trfde> wrote:
: Not a bug. Your sphere simply grows out of the the space POV-Ray considers
: for intersection.
Do you think this limit should be expanded, or are there good reasons to
keep it like it is currently?
--
#macro N(D,I)#if(I<6)cylinder{M()#local D[I]=div(D[I],104);M().5,2pigment{
rgb M()}}N(D,(D[I]>99?I:I+1))#end#end#macro M()<mod(D[I],13)-6,mod(div(D[I
],13),8)-3,10>#end blob{N(array[6]{11117333955,
7382340,3358,3900569407,970,4254934330},0)}// - Warp -
Post a reply to this message
|
|
| |
| |
|
|
From: Thorsten Froehlich
Subject: Re: Disappearing Large Sphere Bug in beta 8
Date: 2 Dec 2001 08:04:36
Message: <3c0a26e4@news.povray.org>
|
|
|
| |
| |
|
|
In article <3c0a236e@news.povray.org> , Warp <war### [at] tagpovrayorg> wrote:
> Do you think this limit should be expanded, or are there good reasons to
> keep it like it is currently?
The current limit is 10^7 by default. I think it is reasonable if you
consider that to find the distance you end up with more than 10^14 and have
to take the sqare root. I think more could be slightly out of the necessary
precision for root finders under some conditions.
Thorsten
____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde
Visit POV-Ray on the web: http://mac.povray.org
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Thorsten Froehlich <tho### [at] trfde> wrote:
: The current limit is 10^7 by default. I think it is reasonable if you
: consider that to find the distance you end up with more than 10^14 and have
: to take the sqare root. I think more could be slightly out of the necessary
: precision for root finders under some conditions.
Perhaps the documentation should mention these kind of limitations so that
people could be aware of them.
--
#macro N(D,I)#if(I<6)cylinder{M()#local D[I]=div(D[I],104);M().5,2pigment{
rgb M()}}N(D,(D[I]>99?I:I+1))#end#end#macro M()<mod(D[I],13)-6,mod(div(D[I
],13),8)-3,10>#end blob{N(array[6]{11117333955,
7382340,3358,3900569407,970,4254934330},0)}// - Warp -
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
in news:3c0a2f0d@news.povray.org Warp wrote:
> Perhaps the documentation should mention these kind of
> limitations so that
> people could be aware of them.
>
What more limitations are there, what is their value and are they
system dependent?
Ingo
--
Photography: http://members.home.nl/ingoogni/
Pov-Ray : http://members.home.nl/seed7/
Post a reply to this message
|
|
| |
| |
|
|
From: Thorsten Froehlich
Subject: Re: Disappearing Large Sphere Bug in beta 8
Date: 2 Dec 2001 16:21:49
Message: <3c0a9b6d$1@news.povray.org>
|
|
|
| |
| |
|
|
In article <Xns### [at] povrayorg> , ingo <ing### [at] homenl>
wrote:
> What more limitations are there, what is their value and are they
> system dependent?
They depend on the system and are subject to be improved without notice. It
might be a good idea to have absolute numbers for this in the docs...
Thorsten
____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde
Visit POV-Ray on the web: http://mac.povray.org
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Well, every primitive probably has it's own limit (cone is extremely sturdy,
as I recall) and it might vary from system to system too but I wouldn't know
if so.
If you weren't looking to do anything but to document a generalization you
could just say very large or very small numbers lead to difficulties in
visiblity or appearance.
BTW, I think light_sources have or had a distance limitation too. Too low
color values for lights isn't limited anymore though, I think, thanks to
Nathan Kopp.
Extreme camera 'angle' or 'direction' (and distance?) also has an effect on
things.
--
text{ttf"arial","bob h",.1,0pigment{rgb 9}translate<-1,-.2,3>}
"ingo" <ing### [at] homenl> wrote in message
news:Xns### [at] povrayorg...
> in news:3c0a2f0d@news.povray.org Warp wrote:
>
> > Perhaps the documentation should mention these kind of
> > limitations so that people could be aware of them.
>
> What more limitations are there, what is their value and are they
> system dependent?
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Thorsten Froehlich <tho### [at] trfde> wrote:
: They depend on the system and are subject to be improved without notice. It
: might be a good idea to have absolute numbers for this in the docs...
Then at least a note that a limitation exists, so people will not be
surprised if they find it.
--
#macro N(D,I)#if(I<6)cylinder{M()#local D[I]=div(D[I],104);M().5,2pigment{
rgb M()}}N(D,(D[I]>99?I:I+1))#end#end#macro M()<mod(D[I],13)-6,mod(div(D[I
],13),8)-3,10>#end blob{N(array[6]{11117333955,
7382340,3358,3900569407,970,4254934330},0)}// - Warp -
Post a reply to this message
|
|
| |
| |
|
|
From: Thorsten Froehlich
Subject: Re: Disappearing Large Sphere Bug in beta 8
Date: 2 Dec 2001 17:43:16
Message: <3c0aae84@news.povray.org>
|
|
|
| |
| |
|
|
In article <3c0aabbf@news.povray.org> , Warp <war### [at] tagpovrayorg> wrote:
> Then at least a note that a limitation exists, so people will not be
> surprised if they find it.
Yes, of course, just no absolute numbers.
____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde
Visit POV-Ray on the web: http://mac.povray.org
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
|
|
