Chris B, thank you very much. It is just what I needed. I can now generate 
my spline curve in seconds into a text file and ready for use instead of 
hours of boring trial and error.  :o)
Dennis

"Chris B" <c_b### [at] btconnectcomnospam> wrote in message 
news:4446ac1b$1@news.povray.org...
>
> "trulayne" <tru### [at] newrrcom> wrote in message 
> news:44469de3$1@news.povray.org...
>>I am in the process of building a landscape.  I am using a USGS Dem image 
>>for my heightfield. I there an easier way to determine the "y" value 
>>knowing the "x" and "z" other than trial and error? Some objects are 
>>fencelines built from spline curves. With the number of points needed for 
>>these curves, the job becomes time intensive doing it by trial and error.
>> Thanks in advance, Dennis
>
> Hi Dennis,
>
> You can use the 'trace' vector function to find a point on a surface. In 
> this case you would use it to shoot a ray straight downwards to intercept 
> the surface and return the coordinates of the point on the surface.
>
> Alternatively I think you should be able to use the 'eval_pigment' 
> predefined function on the image to pick up the color and work out the 
> elevation from that.
>
> Regards,
> Chris B.
>

Post a reply to this message