Gridding/Interpolating a large image

[Ned Horning <nedh(at)lightlink.com>]

Hi, I am an ENVI user and I would like to create a digital elevation
model from a set of contour lines and cannot figure out how to do this
with ENVI or IDL. When I've done this in the past I did a
vector-to-raster conversion to rasterize the contour data and then ran
an interpolation algorithm to generate the DEM. ENVI has a "Raterize
Point Data" option that seems to do what I want but it requires an
ASCII Point file and I don' know how to convert a vector file to an
ASCII point file. IDL has some interesting gridding and interpolation
options but I'm not sure how to implement them on a large 5000 x 6000
Integer image. My guess is IDL can do this easily but my IDL skills
are not all that sharp.

I have a raster image of the contour lines and now all I need to do is
implement some sort of interpolation. The algorithm I've used in the
past was based on the CONSURF algorithm but I think the
Triangulate/Trigrid routines will work but am not sure how to run it
on a large image.

Any help is appreciated.

Ned