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#1
burwelbo

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Recently
we have had to do a bit of contouring. Since we are an ESRI shop we
used ArcGIS and Spatial Analyst. However, we were not very satisfied
with the results. I know there are methods to improve it using filters
and generalizing the lines after but it was very time consuming. I was
wondering what packages people are using to do contouring. Iam looking
for nice smooth lines. I have used Surfer and I like it but was
wondering if anyone ws using anything else that they liked and at a low
cost.

Thanks
Bruce

#2
Hans van der Maarel

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Personally,
given the tools I have at my disposal, I'd do the contouring in FME,
then try and automatically smooth the lines. If I'd have the data in
Illustrator, it'd be easy to just smooth the linework a bit. I doubt
this will give a nice result right away though. Software, especially
GIS software, tends to take a very direct and mathematical approach,
whereas you'd really need some esthetic input as well.


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Red Geographics
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#3
Martin Gamache

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By contouring do you mean interpolating elevation contour lines from a DEM or another form of isoline?

Maybe
you can tell us about your application, and what the intended output
is, your source data, its resolution, and the final scale and interval
you need the isolines to be displayed at.

In general the quality
of your isolines will depend greatly on the quality and resolution of
the surface which depends on the data and methods used to generate the
surface in the first place.

I've been fairly happy with the
results from Manifold in the past and have read of good results from
GRASS. Both are affordable but I think the output will be quite similar
to that of Surfer and Spatial Analyst. I supect the problem lies in the
intervals and details you are trying to get out of a dataset that might
be too coarse for the scale or of otherwise poor quality. For example
if you are trying to get good contours from a 10m DEM which was itself
derived from 1:24k 40' interval contours...you might not get results as
good as the initial contours used in its creation. Try the experiment
of generating a surface from an initial contour dataset and then
generating contours from that surface, then compare the contours....
there will probably be some differences.

And yes there are
line smoothing filters out there that can do a good job to make lines
look better...be careful what you do with these as looking better does
not mean they will be more accurate.

#4
burwelbo

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We
are contouring from a near shore bathymetric grid that we generated
using Landsat data. We then correlated the grid to existing bathymetry.
The purpose of the project is to give Geologists a rough estimate so
they can target future seismic and detailed bathymetric mapping. We are
now trying to generate contours from the grid. We ended up using surfer
and it did a good job.




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