POV-Ray : Newsgroups : povray.beta-test : Height field smoothing Server Time
1 Nov 2024 05:23:18 EDT (-0400)
  Height field smoothing (Message 1 to 2 of 2)  
From: Slime
Subject: Height field smoothing
Date: 25 Apr 2004 15:42:19
Message: <408c149b$1@news.povray.org>
A while ago, in the thread "Height field defects," on 2/1/2004, Warp pointed
out:

>   what worries me the most is that this heightfield should
> be smooth but isn't. The grid is clearly visible and shouldn't. There's
> something wrong here.

I looked at the source code and determined:

> ...At this point, x and z are values from 0 to 1, representing the
coordinates
> in the current square which is being interpolated:
>
> [snip]
>
> Simple bilinear interpolation; except that x and z were first run through
> this "stretch" function:
>
> [snip]
>
> Which pulls x and z closer to the edges of the square. I suspect that if
> this function is not used, that the interpolation may appear more like the
> image Warp provided. I think it's worth a shot to see if it looks better
or
> worse when this function is not used.

I was wondering if anyone involved in the development of 3.6 has
investigated this at all? I figure, if the appearance of height fields is
changing in 3.6 (and it is, due to bugfixes), then it's best to take the
opportunity to make them look as good as possible.

I wouldn't be surprised if the "stretch" function was originally implemented
to try to work around the normal smoothing problem which has been fixed. I
think it's worth taking out to see if the appearance improves (I would
expect that it does). It would also very slightly speed up the rendering of
height fields to avoid the extra function calls.

Any word on this from the developers?

 - Slime
 [ http://www.slimeland.com/ ]


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From: Chris Cason
Subject: Re: Height field smoothing
Date: 6 May 2004 10:26:29
Message: <409a4b15@news.povray.org>
> Any word on this from the developers?

thanks for the reminder on this, the code in question is being fixed.

-- Chris


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