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#1
Dennis McClendon

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Yesterday, I stumbled across this rather specialized repository of GIS data.  Coastlines can be frustrating to cobble together from state-level sources, especially ones that take different approaches to generalization and digitizing. I've only had occasion to use the medium-resolution continental US file, but it was darn close to what I'd already drawn by hand for the western end of Long Island Sound at 100K.


Dennis McClendon, Chicago CartoGraphics
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#2
Michael Schmeling

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A very good coastline is provided by OpenStreetMap:

 

http://openstreetmap...data/coastlines



#3
Charles Syrett

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Dennis, I just came across that NOAA link myself a couple of weeks ago, but my concern is different from yours. I'm working at a very large scale, updating the mapping of a waterfront property which has had some recent difficulties with cliff erosion. Trying to "leave no stone unturned", and keeping in mind the old cartographers' adage that "you gotta draw the line somewhere", I've been trying to update the high tide line, which is normally considered to be the property boundary. The NOAA coastline shapefile, which states in its metadata is derived from LiDAR, is far to generalized to use as the shoreline in a case such as this. Fortunately, NOAA also has the LiDAR bare-earth data available as well, so that recent changes in the high tide level can be determined accurately. For the shoreline itself at this large scale, the 0 contour line does the job!



#4
Daniel Huffman

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Thanks for sharing! I've definitely run into the cobbling-together problem before, and this looks like it could be handy in the future.



#5
Dennis McClendon

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Somehow, in our transformation to GIS, we've lost the design concept that display should be scale-dependent, and that all compilations have an intrinsic scale based on how they were digitized—even data that's stored using 12 decimal places.

 

For large-scale mapping, like Charles is doing, something like OpenStreetMap or a very precise shapefile from a local agency would obviously be a better choice.  The NOAA shorelines are primarily useful for small- and intermediate-scale mapping, where too much detail and precision is a problem, not a feature to be sought.


  • Hans van der Maarel likes this
Dennis McClendon, Chicago CartoGraphics
chicagocarto.com

#6
Hans van der Maarel

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Somehow, in our transformation to GIS, we've lost the design concept that display should be scale-dependent, and that all compilations have an intrinsic scale based on how they were digitized—even data that's stored using 12 decimal places.

 

I couldn't agree more Dennis!

 

My cartographic education was part of the geodesy curriculum. You'd start out with a joint year during which classes from both fields were given and would then specialize for 3 years in either geodesy or GIS/cartography. In the geodesy classes and surveying practica we'd been taught to be as accurate as possible. In the cartography classes generalisation was one of the first subjects covered :)


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