i have been using the pov-ray for modeling remote sensing images, So I have
some questions that i could not find an answer in pov-ray help:

    1.I'm using a PNG file as a height field (DIGITAL TERIAN MODEL - DTM),
this height field is imported to pov-ray to be in size of 1,1,1, I would
like to translate and         rescale the height field back to it's real
size and location. Are the pixels centers placed on the corners or are they
shifted 0.5 pixel inside form each direction ? (Should I use a factor for
translation of :  dx = x0 - 0.5*grid_dx ?). is the image map (png file)
scaling concept similar also to height field scaling and translation
concept?

 2. I'm defining the camera according to right_length vector, I know that
the pixel size in the camera plan is X (1.5 micro m), how to define the
length of right vector: X * columns  or X * (columns -1), generally speaking
how pov ray calculate the ray vector for intersection when using the trace
function ?

 3. How can I get out of pov ray X,Y,Z of the intersections ? I have added
also building to scene (group of poly)

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In article <web.3f5641e0fd79e95a78c628a10@news.povray.org>,
 "saleem" <nomail@nomail> wrote:

>     1.I'm using a PNG file as a height field (DIGITAL TERIAN MODEL - DTM),
> this height field is imported to pov-ray to be in size of 1,1,1, I would
> like to translate and         rescale the height field back to it's real
> size and location.

The "real" size and location is whatever you need it to be. POV 
coordinates have no relation to real-world units, and certainly no 
relation to coordinates on a globe.


> Are the pixels centers placed on the corners or are they
> shifted 0.5 pixel inside form each direction ? (Should I use a factor for
> translation of :  dx = x0 - 0.5*grid_dx ?). is the image map (png file)
> scaling concept similar also to height field scaling and translation
> concept?

I really have no idea what you're asking here...but it sounds like you 
really don't understand how image maps and height fields work. I suggest 
you go back and read the documentation, maybe look at the earlier 
threads in these groups.


>  2. I'm defining the camera according to right_length vector, I know that
> the pixel size in the camera plan is X (1.5 micro m), how to define the
> length of right vector: X * columns  or X * (columns -1), generally speaking
> how pov ray calculate the ray vector for intersection when using the trace
> function ?

Again, I have no idea what you're asking. You may be going at it the 
wrong way, try describing exactly what you're attempting to do rather 
than assuming it must be done a certain way.


>  3. How can I get out of pov ray X,Y,Z of the intersections ? I have added
> also building to scene (group of poly)

Look up the trace() function.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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