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From: Ken
Subject: Height Field Warning
Date: 12 Jul 1999 19:29:47
Message: <378A79E7.53DEDF76@pacbell.net>
People (term used lightly in some cases),

  By sheer accident I ran into a terrible problem rendering a HF logo
today. I was helping another Pov user via email who had sent me a logo
image he wanted to try to render in 3d. The image he sent was in .tif
format so to work with pov's HF object I first converted it to a .gif
image. After writing the .pov scene to my satisfaction I then rendered
the scene.
  It was at this point I started doubting my abilities at using this
program. The logo was was simply white text on a black background. One
would expect that the results would be raised letters with a little
background that could be easily removed with the water level modifier.
Nope ! Did not look that way. Instead I got a solid block with the
letters REMOVED !
  I shook my head, scratched a few places, and then decided I had the
colors reversed from what they should be. I opened the image in PSP and
made a negative of the original. Upon rendering the scene again with the
modified image I once again had exactly the same problem. WHAT you might
now be saying ? I sure did !
  This nonsense went on for about 20 min of trying various options but for
the life of me I could not figure out what had happened to a proven method
of 3d logo creation. It was only after shutting down the program, eating
lunch, and considerable pondering did I discover the error of my ways.
 I had saved the gif image with transparency set to the background color
option set in PSP. When the pov went to render the file it found the
transparency info contained in the gif image and was reversing (?) the
operation of the HF process. Ultimately I re-saved with transparency
disabled and it worked as expected.

  I just though you all might be interested in knowing that this too can
happen to you and if it does you will know how to correct for it.


-- 
Ken Tyler

mailto://tylereng@pacbell.net


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From: Bill DeWitt
Subject: Re: Height Field Warning
Date: 13 Jul 1999 00:41:25
Message: <378ac375@news.povray.org>
Ken <tyl### [at] pacbellnet> wrote :
>  I had saved the gif image with transparency set to the background color
> option set in PSP. When the pov went to render the file it found the
> transparency info contained in the gif image and was reversing (?) the
> operation of the HF process. Ultimately I re-saved with transparency
> disabled and it worked as expected.
>

    I had something similar happen to me over the weekend. While editing a
HF in Corel I switched to the imagemap, did some erasing, and switched back
to the HF and removed a similar section. When I rerendered the edges of the
erased area were suddenly at full height.
    Turns out the color I erased with was from the imagemap (I suppose) and
must have gotten added to the palette at the end (#255) when I saved,  even
though it looked black.
    Anyway, undoing and then selecting a low value color from the HF then
re-erasing fixed it.

    I don't remember if transparency is saved at the #255 position in the
palette.


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From: Bob Hughes
Subject: Re: Height Field Warning
Date: 13 Jul 1999 01:03:08
Message: <378AC870.7E315278@aol.com>
One of the reasons I uncheck any of those "Use Background Color for
Transparency" boxes I come across since I never am sure where that color
is going to be.


Ken wrote:
> 
>  People (term used lightly in some cases),
> 
>   By sheer accident I ran into a terrible problem rendering a HF logo
> today. I was helping another Pov user via email who had sent me a logo
> image he wanted to try to render in 3d. The image he sent was in .tif
> format so to work with pov's HF object I first converted it to a .gif
> image. After writing the .pov scene to my satisfaction I then rendered
> the scene.
>   It was at this point I started doubting my abilities at using this
> program. The logo was was simply white text on a black background. One
> would expect that the results would be raised letters with a little
> background that could be easily removed with the water level modifier.
> Nope ! Did not look that way. Instead I got a solid block with the
> letters REMOVED !
>   I shook my head, scratched a few places, and then decided I had the
> colors reversed from what they should be. I opened the image in PSP and
> made a negative of the original. Upon rendering the scene again with the
> modified image I once again had exactly the same problem. WHAT you might
> now be saying ? I sure did !
>   This nonsense went on for about 20 min of trying various options but for
> the life of me I could not figure out what had happened to a proven method
> of 3d logo creation. It was only after shutting down the program, eating
> lunch, and considerable pondering did I discover the error of my ways.
>  I had saved the gif image with transparency set to the background color
> option set in PSP. When the pov went to render the file it found the
> transparency info contained in the gif image and was reversing (?) the
> operation of the HF process. Ultimately I re-saved with transparency
> disabled and it worked as expected.
> 
>   I just though you all might be interested in knowing that this too can
> happen to you and if it does you will know how to correct for it.
> 
> --
> Ken Tyler
> 
> mailto://tylereng@pacbell.net

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/homepage.htm
 mailto://inversez@aol.com?Subject=PoV-News


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From: Ken
Subject: Re: Height Field Warning
Date: 13 Jul 1999 01:14:21
Message: <378ACA92.AA59681@pacbell.net>
Bill DeWitt wrote:

>     I don't remember if transparency is saved at the #255 position in the
> palette.

  In PSP there is a seperate options dialog you have to activate when
doing a save_as or save operation. If three days ago you had opened the
extra dialog and choosen to save with transperency the next time you use
the program it will remember that last used setting. You have no way of
knowing that it is set one way or another unless you check and that is
what bit me on this one.

-- 
Ken Tyler

mailto://tylereng@pacbell.net


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From: Ken
Subject: Re: Height Field Warning
Date: 13 Jul 1999 01:35:29
Message: <378ACF88.85B62C31@pacbell.net>
Bob Hughes wrote:
> 
> One of the reasons I uncheck any of those "Use Background Color for
> Transparency" boxes I come across since I never am sure where that color
> is going to be.

I usualy have set to off but I made a mistake all right ! I Ken Tyler made
a mistake ! Now let if go :)

  I am hoping that others may learn from 'My' mistake and not repeat it. If
it were not for my considerable intellegence I might have made a bug report
instead accusing Pov v3.1g of having a bug. But this didn't happen now did
it ?

-- 
Ken Tyler

mailto://tylereng@pacbell.net


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From: Remco de Korte
Subject: Re: Height Field Warning
Date: 13 Jul 1999 05:24:59
Message: <378B04EF.2AFB1272@xs4all.nl>
Ken wrote:
> 
>   I just though you all might be interested in knowing that this too can
> happen to you and if it does you will know how to correct for it.
> 
> --
> Ken Tyler
> 
> mailto://tylereng@pacbell.net

Good grief! ;-)
Would this be the cause of my premature baldness over a bump_map I can't seem to
get to work? 
On the other hand: I tried it with PNGs and couldn't get the results I wanted
(and expected) there either. Must be me, I guess...

Remco
http://www.xs4all.nl/~remcodek/


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From: Lewis
Subject: Re: Height Field Warning
Date: 13 Jul 1999 09:17:23
Message: <378B3BBD.A4D7DCE4@netvision.net.il>
ken, with all due respect to your gigantic intelligence and titanic
rendering abilities (not to mention your lynk bank), i did this exact
operation last week in 2 minutes.

Ken wrote:
> 
>  People (term used lightly in some cases),
> 
>   By sheer accident I ran into a terrible problem rendering a HF logo
> today. I was helping another Pov user via email who had sent me a logo
> image he wanted to try to render in 3d. The image he sent was in .tif
> format so to work with pov's HF object I first converted it to a .gif
> image. After writing the .pov scene to my satisfaction I then rendered
> the scene.
>   It was at this point I started doubting my abilities at using this
> program. The logo was was simply white text on a black background. One
> would expect that the results would be raised letters with a little
> background that could be easily removed with the water level modifier.
> Nope ! Did not look that way. Instead I got a solid block with the
> letters REMOVED !
>   I shook my head, scratched a few places, and then decided I had the
> colors reversed from what they should be. I opened the image in PSP and
> made a negative of the original. Upon rendering the scene again with the
> modified image I once again had exactly the same problem. WHAT you might
> now be saying ? I sure did !
>   This nonsense went on for about 20 min of trying various options but for
> the life of me I could not figure out what had happened to a proven method
> of 3d logo creation. It was only after shutting down the program, eating
> lunch, and considerable pondering did I discover the error of my ways.
>  I had saved the gif image with transparency set to the background color
> option set in PSP. When the pov went to render the file it found the
> transparency info contained in the gif image and was reversing (?) the
> operation of the HF process. Ultimately I re-saved with transparency
> disabled and it worked as expected.
> 
>   I just though you all might be interested in knowing that this too can
> happen to you and if it does you will know how to correct for it.
> 
> --
> Ken Tyler
> 
> mailto://tylereng@pacbell.net


Post a reply to this message

From: Remco de Korte
Subject: Re: Height Field Warning
Date: 13 Jul 1999 10:56:14
Message: <378B440B.E234E98F@xs4all.nl>
Lewis wrote:
> 
> ken, with all due respect to your gigantic intelligence and titanic
> rendering abilities (not to mention your lynk bank), i did this exact
> operation last week in 2 minutes.
> 

Did you share your wisdom?

Remco
http://www.xs4all.nl/~remcodek/pov.html


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From: Margus Ramst
Subject: Re: Height Field Warning
Date: 13 Jul 1999 10:57:31
Message: <378B53F9.5C4D6FB@peak.edu.ee>
Ken wrote:

/.../
>   This nonsense went on for about 20 min of trying various options but for
> the life of me I could not figure out what had happened to a proven method
> of 3d logo creation. It was only after shutting down the program, eating
> lunch, and considerable pondering did I discover the error of my ways.

I bet it was eating lunch that did the trick :)

BTW, it would be nice if the transparency info in GIF could be put to good use,
such as clipping out the transparent sections. The alpha channel could also be
used, clipping out completely transparent parts. I can think of many
applications for this (although all can be simulated with texture maps)
Does this sound viable?

Margus


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From: Ken
Subject: Re: Height Field Warning
Date: 13 Jul 1999 11:06:15
Message: <378B552F.647D1263@pacbell.net>
Margus Ramst wrote:

 
> BTW, it would be nice if the transparency info in GIF could be put to good use,
> such as clipping out the transparent sections. The alpha channel could also be
> used, clipping out completely transparent parts. I can think of many
> applications for this (although all can be simulated with texture maps)
> Does this sound viable?
> 
> Margus

  I think simply using black along with the water lever modifier in those
areas you wish to clip is a more reliable system. What was actually being
represented by the Hf was not the black field or the transparent white
field but instead it was the boundry layer between the two. If you experiment
with it a little bit you will see what I am talking about. I am surprised
it returned any height values at all. It may be that PSP was antialiasing
the pixels at the boundry and that is why there was something besides a
flat object produced.

-- 
Ken Tyler

mailto://tylereng@pacbell.net


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