POV-Ray : Newsgroups : povray.unofficial.patches : Re: What's wrong with the normals in megapov? (~100k) Server Time
2 Sep 2024 16:17:40 EDT (-0400)
  Re: What's wrong with the normals in megapov? (~100k) (Message 1 to 3 of 3)  
From: Fabian Brau
Subject: Re: What's wrong with the normals in megapov? (~100k)
Date: 15 Dec 1999 04:22:31
Message: <38575E6A.810C7411@umh.ac.be>
To be precise (because I didn't say that povray is good and 
Megapov is not good, because I haven't check this :)): 

I said:
> The absolute size of an object has no importance! Only 
> the relative size between object is important. If you scale a complete 
> scene by a factor x and if you change the camera in the good way, you
> must 
> notice that nothing has changed, you must obtain the same scene, the 
> same image.

I didn't check yet but if MegaPov do this and not Povray so MegaPov is
the good one :)!

Fabian.




Nathan Kopp wrote:
> 
> Nieminen Juha <war### [at] punarastascstutfi> wrote ...
> > Nathan Kopp <Nat### [at] koppcom> wrote:
> > : Hmmm... you'll have to mess with the 'accuracy' to get that second image
> to
> > : sharpen up.  Then it will look the way you want it to.
> >
> >   This 'accuracy' keyword is new to me. What does it do?
> 
> Time to look at the documentation.  ;-)
> (It adjusts the coarseness of the points used to estimate the gradient of
> the pattern which is used to determine the normal.)
> 
> >   If I scale an object 5 times larger and move the camera and light source
> > 5 times farther, I would expect to get the exact same image.
> 
> Yes.  I agree.  That is the reason it needs to be fixed.
> 
> >   It would be this way if it was a heightfield instead of a normal
> modifier.
> > Thus I would expect the normal modifier to behave like a heightfield. What
> > you are doing is changing the slope of the normal modifier when scaling.
> > With a heighfield the slope doesn't change if we scale it uniformly.
> >   So I think that povray's default behaviour is the correct one.
> 
> Unfortunately, no.  The official POV-Ray will at times fail at what you want
> it to do.  See my post in text.scene-files for a demonstration.  MegaPov
> will act in the way you describe.
> (followups to povray.unofficial.patches)
> 
> Anyway, in  the next MegaPov you will be able to use #version 3.1 to attain
> backwards compatibility in this area (as well as with layered textures).
> 
> -Nathan


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From: Fabian Brau
Subject: Re: What's wrong with the normals in megapov? (~100k)
Date: 15 Dec 1999 04:27:58
Message: <38575FB6.F0F0ABF6@umh.ac.be>
???? Waht does my message here?

Fabian Brau wrote:
> 
> To be precise (because I didn't say that povray is good and
> Megapov is not good, because I haven't check this :)):
> 
> I said:
> > The absolute size of an object has no importance! Only
> > the relative size between object is important. If you scale a complete
> > scene by a factor x and if you change the camera in the good way, you
> > must
> > notice that nothing has changed, you must obtain the same scene, the
> > same image.
> 
> I didn't check yet but if MegaPov do this and not Povray so MegaPov is
> the good one :)!
> 
> Fabian.
> 
> Nathan Kopp wrote:
> >
> > Nieminen Juha <war### [at] punarastascstutfi> wrote ...
> > > Nathan Kopp <Nat### [at] koppcom> wrote:
> > > : Hmmm... you'll have to mess with the 'accuracy' to get that second image
> > to
> > > : sharpen up.  Then it will look the way you want it to.
> > >
> > >   This 'accuracy' keyword is new to me. What does it do?
> >
> > Time to look at the documentation.  ;-)
> > (It adjusts the coarseness of the points used to estimate the gradient of
> > the pattern which is used to determine the normal.)
> >
> > >   If I scale an object 5 times larger and move the camera and light source
> > > 5 times farther, I would expect to get the exact same image.
> >
> > Yes.  I agree.  That is the reason it needs to be fixed.
> >
> > >   It would be this way if it was a heightfield instead of a normal
> > modifier.
> > > Thus I would expect the normal modifier to behave like a heightfield. What
> > > you are doing is changing the slope of the normal modifier when scaling.
> > > With a heighfield the slope doesn't change if we scale it uniformly.
> > >   So I think that povray's default behaviour is the correct one.
> >
> > Unfortunately, no.  The official POV-Ray will at times fail at what you want
> > it to do.  See my post in text.scene-files for a demonstration.  MegaPov
> > will act in the way you describe.
> > (followups to povray.unofficial.patches)
> >
> > Anyway, in  the next MegaPov you will be able to use #version 3.1 to attain
> > backwards compatibility in this area (as well as with layered textures).
> >
> > -Nathan


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From: Nieminen Juha
Subject: Re: What's wrong with the normals in megapov? (~100k)
Date: 15 Dec 1999 04:44:04
Message: <385762e4@news.povray.org>
Fabian Brau <fab### [at] umhacbe> wrote:
:> The absolute size of an object has no importance! Only 
:> the relative size between object is important. If you scale a complete 
:> scene by a factor x and if you change the camera in the good way, you
:> must 
:> notice that nothing has changed, you must obtain the same scene, the 
:> same image.

: I didn't check yet but if MegaPov do this and not Povray so MegaPov is
: the good one :)!

  No, povray does this (except if you use normal_maps) and megapov doesn't.
Megapov does it the wrong way.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/


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