Roland Mas wrote:

> I wondered how long it would take until someone would notice this...
> I'm afraid you all lost :-)
> 
> The doc says it all (almost):
> 
> --- Cut here ---
> 7.8.4            HF_Gray_16
> 
> The hf_gray_16 setting is useful when using POV-Ray to generate
> heightfields for use in other POV-Ray scenes. The syntax is...
> 
>   global_settings { hf_gray_16 BOOLEAN }
> 
> The boolean value turns the option on or off. If the keyword is
> specified without the boolean value then the option is turned on. If
> hf_gray_16 is not specified in any global_settings statement in the
> entire scene then the default is off.
> 
> When hf_gray_16 is on, the output file will be in the form of a
> heightfield, with the height at any point being dependent on the
> brightness of the pixel.  The brightness of a pixel is calculated in
> the same way that color images are converted to grayscale images:
> 
>   height = 0.3 * red + 0.59 * green + 0.11 * blue
> 
> Setting the hf_gray_16 option will cause the preview display, if used,
> to be grayscale rather than color. This is to allow you to see how the
> heightfield will look because some file formats store heightfields in
> a way that is difficult to understand afterwards. See section "Height
> Field" for a description of how POV-Ray heightfields are stored for
> each file type.
> --- Cut here ---
> 
> Maybe it should have been a bit clearer.  Anyway, the output can be
> turned into a sixteen bit per pixel black and white image file.  I
> first wrote "at least in Truevision format", but it is not true.  My
> further tests reveal that it works with "PNG" format.  Hence my
> superseding of my previous article.
> 
> Roland.
> --
> Roland Mas
> 

> - Genki desu, ture en zinc.



   For the purposes of the i.r.t.c. contest this method is invalid. Yes it
 is true that the image is in 16 bit gray scale but it is also true that
 if try to view it in a normal image viewing program it is not recognizable
 as a normal image. In most cases they an ugly green in color and highly
 pixelated in appearance. To make it visible it needs to be color and format
 converted. If you are going to do that you might as well use an image
 conversion program to turn into 256 shades of gray and gain the added color
 depth in the process. Either way it's not allowed in the competition so it's
 a moot point. It is for these reasons I did not bring it up before simply
 because it's not the solution the original poster will need to accomplish
 his goal.


-- 
Ken Tyler

mailto://tylereng@pacbell.net

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