POV-Ray : Newsgroups : povray.general : Pov 3.1beta4 Error message Server Time
13 Aug 2024 17:24:44 EDT (-0400)
  Pov 3.1beta4 Error message (Message 1 to 2 of 2)  
From: K  Tyler
Subject: Pov 3.1beta4 Error message
Date: 12 Aug 1998 17:03:55
Message: <35D1E6D5.FB2E5F89@pacbell.net>
I received an error mesage today from a scene I rendered conataining
1 height field with an image map for texture, and one backgroud plane.

The message read: Illegal Grid Value in dda_traversal ( ).

The scene seemed to render properly but the illegal message
was repeated 14 times in the message window.

Any body want to speculate ?

K.Tyler


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From: Jerry Anning
Subject: Re: Pov 3.1beta4 Error message
Date: 12 Aug 1998 21:53:59
Message: <35D2392B.D3E563EC@dhol.com>
K. Tyler wrote:
> 
> I received an error mesage today from a scene I rendered conataining
> 1 height field with an image map for texture, and one backgroud plane.
> 
> The message read: Illegal Grid Value in dda_traversal ( ).
> 
> The scene seemed to render properly but the illegal message
> was repeated 14 times in the message window.

This is a well known bug from previous POV versions.  I know of no
successful fixes as yet.  It has to do with floating point accuracy and
height fields.  Very roughly, sometimes you shoot a ray "between the
cracks" of a height field.  Sometimes it has no visible effect,
sometimes you get small artifacts.  Sometimes moving the camera,
look_at, or height field slightly will help.  A DejaNews search on cgrr
will find several threads about this.  Usually, it does little or no
harm.

Jerry Anning
cle### [at] dholcom


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