6 replies to this topic

[gp1]

Ok, maybe I missed a discussion on this being a noob and all

Some
of you for sure have worked on government projects where the client
supplies a typical 10m DEM and asks you to generate 100' contours in
vector form from them.

We have ArcGIS 9 but I am FAR from knowing what I am doing in that application.

Anyone willing to post tutorials on how to accomplish this task?

My goal would be to get somewhat clean vectors out of Arc and into MAPublisher.

Thanks all

[Martin Gamache]

You will need to have spatial analyst or 3d analyst.

[Hans van der Maarel]

Or FME... Or Manifold...

[burwelbo]

"I've
been doing some testing using ArcGIS for generating some clean
contours. A good procedure I found is to apply a neighbourhood filter
of 5x5 or 7x7 then generate your contours. You can then apply the
generalization tool to smooth the lines further. If you do a search in
Arctoolbox, the 3 tools you need are Focal Statistics, Contour and
Smooth Line. I attached a graphic of my results. The contours were
produced using the 90 m SRTM data contoured at 50 m intervals. I used a
5x5 circular neighbourhood filter. I didn't need to apply the smooth
line tool.

Hope this helps.

Bruce

Attached thumbnail(s)
[url="http://"http://www.cartotalk.com/index.php?act=Attach&type=post&id=356"]http://"http://www.cartotalk.com/index.php...ype=post&id=356[/url] "

Attached Files

•  contours.jpg   644.59K   90 downloads

[Hans van der Maarel]

Bruce,

Which
SRTM tile is that (and which part of it?), I think it'd be nice to try
and do this same thing in a couple of other GIS software tools and
compare the results.

[burwelbo]

It
was roughly 12-13 North Latitude by 40 deg 30min to 41 deg 30 min East
Longitude. The area was in Djibouti near Ethiopia on the coast of the
Gulf of Aden. One thing I noticed is that the holes in the data cause a
problem. They make jagged looking contours at 0. I just selected them
all and deleted them. This will cause innacurate rresults even if you
fill them in using software like 3 DEM.

[gp1]

Thanks for the replies guys

Bruce, I will give your process a try on some DEMs we have in-house and see how it works out..