"Gilles Tran" <gitran_nospam_@wanadoo.fr> wrote:

> news:web.41207b10e6dfd373e5987fa60@news.povray.org...
>
> > I think it's OK also because I set :
> > - DEM_size_x and DEM_size_z accordingly to the size of my DEM file,
> > - DEM_size_y is set to 65535 as I use 16bits PNG file.
>
> It's not the size of the DEM file you need, but the size of the real thing
> in meters (it's easier that way in any case).

Sure.

> For instance, if the terrain is supposed to be 2000m (width) x 2000m
> (length) x 2341m (maximum height), the scaling should be <2000,2341,2000>.

My DEM file have a resolution of 75m by pixel and my files is 512x512
pixels.
So I set DEM_size_x and DEM_size_z to 512 * 75 = 38400.

> Of course, this assumes that the maximum height in the DEM file is
> translated as pure white in the height field, which may not be the case. It
> really depends on how the heights are converted, i.e. what would be the
> white value of a map from the Netherlands vs a map of the Himalayas...

The value of each dot of the DEM file is the real altitude in meters. For
example, Annecy's lac altitude is 444m so, the value of this point in 444
(red*256 + green).
As the maximum value for this 16bits value is 65535, I put 65535 as Y scale
....

Laurent

Post a reply to this message