POV-Ray : Newsgroups : povray.general : I think I found the funky hieght field trouble! : Re: I think I found the funky hieght field trouble! Server Time
22 Jun 2024 15:53:06 EDT (-0400)
  Re: I think I found the funky hieght field trouble!  
From: William F Pokorny
Date: 22 Mar 2023 05:37:57
Message: <641acc75$1@news.povray.org>
On 3/21/23 15:03, Leroy wrote:
> 
> You know the spotted base where the height=0.
> I was going through the 3.6 source code and there is:
> 
> const DBL HFIELD_OFFSET = 0.001;
> 
> This was added and subtracted to the bounding box as well as other things I
> haven't chased down.
> 
> The point is that if I use a water_line of .001 the spots goes away.
> 
> I don't know about other versions. I guess I need to chase them down.
> 
> Have Fun!
> 
Thanks for the information.

You're not the only one who's reported strangeness near 0.0 in the 
height field. Now a few years back, I came across a blog where someone 
was creating height_fields of her home terrain and using POV-Ray renders 
to look around. She had trouble when the camera positions got near 0.0 
which I'd bet was a near zero bug of some kind too.

I'm aware of that water_level setting, but I've never played with it. 
All those buttons and not the time to push them all! :-)

The height_field code is old and due a refresh I expect. Someday...

---

Since we are talking height_fields! The upcoming version (R7 v0.6.1) of 
my povr fork removes the special <=8 bit, red weighted color to grey 
scale conversion. No matter the color image channel depth the internal 
.grayscale() conversion will get used.

Plus I made indexed images illegal as input. The old code used the index 
values in such images to create an equivalent gray level, but only with 
256 index values. Further the height, for historical reasons, was muted 
in that the max height returned was never more than 0.4% of the full 
height_field height.

So! I think, I've eliminated the image based height_field flakiness in 
the povr fork. I believe, too, this was the last of the special red 
weighted, red+green to grayscale conversion code that was in use.

Bill P.


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