Has anyone ever seen the error message 
Illegal grid value in dda_traversal(). ?
I'm working on a large animation and there are lots of reflections, et
al., going on.  Worried that it will eventually kill the project I'm
working on.  A whole pane's worth of output is pasted below, with the
message at the very end. 

_______________________________
Greg M. Johnson
http://members.xoom.com/gregjohn




  Antialiasing.........On  (Method 1, Threshold 0.300, Depth 3, Jitter
1.00)
  Radiosity...........Off
Animation Options
  Initial Frame..       1  Final Frame....      50
  Initial Clock..   0.000  Final Clock....   1.000
  Cyclic Animation....Off  Field render........Off  Odd
lines/frames....Off
Redirecting Options
  All Streams to console..........On
  Debug Stream to console.........On
  Fatal Stream to console.........On
  Render Stream to console........On
  Statistics Stream to console....On
  Warning Stream to console.......On

Scene contains 18 frame level objects; 2 infinite.

 00:00: 3 so far, Rendering frame 1, going to 50.Illegal grid value in
dda_traversal().
Illegal grid value in dda_traversal().
Illegal grid value in dda_traversal().

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I got one of those about 2 months ago in a scene with
a height field. It did not seem to effect the out come of
the project though.

Ken Tyler

Greg M. Johnson wrote:

> Has anyone ever seen the error message
> Illegal grid value in dda_traversal(). ?
> I'm working on a large animation and there are lots of reflections, et
> al., going on.  Worried that it will eventually kill the project I'm
> working on.  A whole pane's worth of output is pasted below, with the
> message at the very end.
>
> _______________________________
> Greg M. Johnson
> http://members.xoom.com/gregjohn
>

Post a reply to this message

Greg M. Johnson wrote:
> 
> Has anyone ever seen the error message
> Illegal grid value in dda_traversal(). ?

Do a dejanews search in povray.general and cgrr for "dda_traversal".  Go
back at least a couple of years.  This has been hashed over periodically
in both places.  Basically, you have a ray going "between the cracks" of
the height field due to an arithmetic accuracy problem.  Sometimes it
does no harm.  Sometime you get black dot or line artifacts.  I know of
no successful patch so far.  I also know no completely reliable
workaround.  The best bet is to slightly joggle the camera position
and/or angle.  This, BTW, would be a good candidate for the VFAQ.

Jerry Anning
cle### [at] dholcom

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Jerry Anning wrote:

>  This, BTW, would be a good candidate for the VFAQ.
>
> Jerry Anning
> cle### [at] dholcom

Good idea so I forewarded this message to Warp.

Ken Tyler

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Jerry Anning <cle### [at] dholcom> wrote:
: This, BTW, would be a good candidate for the VFAQ.

  I added your answer.

-- 
                                                           - Warp. -

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I thought this had been fixed in the 3.02 version?
Knew it was present in 3.0, but not 3.02...
Yes, I just checked a scene I made a while back that was infamous for this 
particular error and it didn't show just now when I tried it again (had to be 
sure).
So check your version and please let us know if it's 3.02. If it's 3.1 maybe 
make a posting in the bug report area.

Message <360### [at] aolcom>, Greg M. Johnson  typed...
>
>Has anyone ever seen the error message 
>Illegal grid value in dda_traversal(). ?
>I'm working on a large animation and there are lots of reflections, et
>al., going on.  Worried that it will eventually kill the project I'm
>working on.  A whole pane's worth of output is pasted below, with the
>message at the very end. 
>
>_______________________________
>Greg M. Johnson
>http://members.xoom.com/gregjohn
>
>
>
>
>  Antialiasing.........On  (Method 1, Threshold 0.300, Depth 3, Jitter
>1.00)
>  Radiosity...........Off
>Animation Options
>  Initial Frame..       1  Final Frame....      50
>  Initial Clock..   0.000  Final Clock....   1.000
>  Cyclic Animation....Off  Field render........Off  Odd
>lines/frames....Off
>Redirecting Options
>  All Streams to console..........On
>  Debug Stream to console.........On
>  Fatal Stream to console.........On
>  Render Stream to console........On
>  Statistics Stream to console....On
>  Warning Stream to console.......On
>
>Scene contains 18 frame level objects; 2 infinite.
>
> 00:00: 3 so far, Rendering frame 1, going to 50.Illegal grid value in
>dda_traversal().
>Illegal grid value in dda_traversal().
>Illegal grid value in dda_traversal().

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/POVring.html
=Bob

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VerseCurse wrote:

> I thought this had been fixed in the 3.02 version?
> Knew it was present in 3.0, but not 3.02...
> Yes, I just checked a scene I made a while back that was infamous for this
> particular error and it didn't show just now when I tried it again (had to be
> sure).
> So check your version and please let us know if it's 3.02. If it's 3.1 maybe
> make a posting in the bug report area.
>

If you want verification that it still exists I encountered this error
message using POV-Ray 3.1b4 back in the middle of august. You
can probably find my post asking what it was on povray.general.

Ken Tyler

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