I have been, over the last couple of years, playing with creating(!) DEMs
using a hybrid of MapInfo/MapBasic and Delphi approaches to generate DEMs on
a 10-metre grid over an area of around 30x18 km (a lot of points) and the
gradients associated with each grid point. The basis of the DEMs was a
contour map at 5-metre intervals, and the points were interpolated using the
distance to nearest contour either side and the proximity to spot heights,
usually (I think!) on summits between the contour lines. The results were,
at least, believable if not accurate, and I have used them in producing
sunshade relief maps (if I understand the term correctly: I am neither a
cartographer nor a geographer) to form a raster backdrop to thematic
mapping. Is this the kind of thing you had in mind? If so, I can e-mail you
a few samples.
Regards
GrahamOB
----- Original Message -----
From: Matt.Wilkie <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, December 01, 1999 7:50 PM
Subject: RE: MI DEM Review, request for contribution
>
> >Programs generally don't create DEMs, they read them.
> >
> >Are you referring to the manipulation of DEMs? Perspective
> >viewing? Speed?
> >Quality of shaded maps or contours? Interpolation of a surface
> >from a few XYZ points?
>
> "generally" depends on which "general area" of activity you
> are in. :) I'm in the area of creating dems. And to be more
> precise, a DEM can be a specific product/file format or a
> general term describing elevation models in general (there's
> that word again :).
>
> For my project, I'm evaluating the quality of elevation models
> created by various programs from a specific vector dataset.
> Quality in this context is a nebulously defined mix of my own
> peculiar blend of aesthetics and objectivity. The tools I will
> be using in my quest include sunshade relief, re-contouring,
> perspective views, and anything else I can think of to help
> shed light.
>
> cheers,
>
> -matt
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