6 replies to this topic

[Kevin McManigal]

Hi folks, this map is from a final paper for my summer field course in Alaska. We skied 180 miles across the Juneau Icefield into Canada, over two months. The Taku Glacier is the largest outlet stream of the Icefield, and has advanced over 5km in the last hundred years. The USGS map sites 1948 air photos, but we determined that the position on the current topo is around 1973. This has caused some confusion when trying the estimate the rate of advance. I have some design questions: I'm sure you folks have already run into this, but is there an easy way to vectorize the jagged raster topo lines generated in ArcMap? I tried CS2 live trace, but that made them all polygons that needed to be cut. My partner Cassie ended up hand tracing them all.

Please let us know what you think, thanks, Kevin

Sorry, I tried to add the map, but it was to large. I went out to resize it, but the site wouldn't let me back on last night. Here it is. ( 500kb per map seems kind of small, what other options do we have if the map is not online?)

Attached Files

•  LatestTakucountors.jpg   478.59K   387 downloads

[frax]

I think you might have missed to put in the link...

If you have grid raster data (not just image) in ArcMap, you can vectorize there (you might need ArcInfo and spatial analyst though...)

[Martin Gamache]

I'm sure you folks have already run into this, but is there an easy way to vectorize the jagged raster topo lines generated in ArcMap? I tried CS2 live trace, but that made them all polygons that needed to be cut. My partner Cassie ended up hand tracing them all. 

Please let us know what you think, thanks, Kevin

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Kevin,

Is there supposeto be a map posted with this question? The Gallery is usually where we post maps for review/critique... I look forward to seing this.

mg

[frax]

looks nice!

It looks quite dark though, and I am not sure what the main thing you want to communicate here is -- is it the movement of the glacier? (is that the blue lines on the glacier, or is that just the elevation) If it is like that I would try to remove a lot of the other information and maybe lose the imagery altogether. Maybe use shaded relief instead of isolines, etc. (if it is more a nice overview of the area I would treat the map differently)

On the issue of the jagged thingies -- you mention them as jagged lines - is it that these are lines already in ArcMap, but just jaggy? then try simplify in illustrator (or generalize in Arc - the latter esp if you want to maintain topology)

[Kevin McManigal]

Thanks for the comments. The map printed much lighter. It was intended to be used for comparison with the USGS topographic map that has not been updated for over 30 years. To show the change over time in the paper, I created an oblique view that shows the position of the ice at different years.

As far as the contour lines that Arc generated, even when in vector they have a raster look to them, with many nodes and steps. When simplified they seemed to loose detail and their connection with the topography. I'll keep experimenting.

Attached Files

•  TakuTopo.jpg   220.04K   211 downloads
•  TakuLines1.jpg   320.98K   215 downloads
•  redcontours.jpg   367.77K   170 downloads

[frax]

I like the oblique view! (even though it is very dark). For your generalization issue - to retain topology you have to do it in Arc, it can be quite tricky to tune all the parameters there.

If that is not an issue, I am very happy with the "Simplify..." dialog in Illustrator, try that with parameter value of 96-98 and see what you get...

[tsring]

Kevin,

I had occasion to visit a good longime buddy who has lived in Juneau for 14 years, who has worked this whole time at BLM Mineral resources a Geologist. He has a Cessna 172 on floats and we had three clear days during my visit the last week August 2005. One of those days we flew from Juneau to Atlin, BC. The Icefield was going to be too cloudy to navigate safely so we opted for the route that begins with the Taku Inlet. I shot a number of photos at about a thousand feet ASL of Taku Glacier and ones around it.

My showing of these images has evolved from the idea of putting them on some sharing site like Shutterfly which I realized was pleagued with advertising, to a much more sophisticated presentation that frankly has had me busy for dozens of hours on just this Juneau-Atlin adventure. I am making a web gallery of this flight and the visit to Atlin, and will have a number of subsequent galleries with different themes based on splitting up the 550+ images I shot while there.

I did a Google search to find the names of Taku's surrounding glaciers and was fortunate to find the one you made. I also seem to have stumbled on a very interesting group site. So I got the names I needed, but I love your map and would like your permission to use it in my gallery. I'd also like to send you the link to the gallery when it is done. Please tell me how to handle permission to use your map. I love it. Thomas Ring - Scottsdale Arizona. PS I am attaching here one shot of Taku Glacier shot Sept 2 2005. I realize this is a map site not a photography site. But I was not sure you would otherwise see the angle I got on it.

Thanks for the comments. The map printed much lighter. It was intended to be used for comparison with the USGS topographic map that has not been updated for over 30 years. To show the change over time in the paper, I created an oblique view that shows the position of the ice at different years.

As far as the contour lines that Arc generated, even when in vector they have a raster look to them, with many nodes and steps. When simplified they seemed to loose detail and their connection with the topography. I'll keep experimenting.

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Attached Files

•  TakuGlacier090205.jpg   355.55K   137 downloads