Ask A Cartographer

Creating Boundary Line

July 31 2009 | 0 comments
Categories: Map Data

I am trying to create a boundary line around a specific level of a contour that has been imported from surfer using the ASCII to Raster converter. Is there a way to do this without changing the entire contour level color? I just want to outline the specific level so that it easily distinguished from the other levels. You better not say polylines :)

I've attached some map to show what I've been doing.

Also, the map I'm using is missing some quadrants is there a way for me to download a free global map or even just the quadrants I'm missing???


Mapping Center Answer:

None of us are familiar with what Surfer outputs (I haven't used it since I was in grad school 17 years ago).  So, there's not much we can do there in terms of having any idea about what the ASCII to Raster tool produces with Surfer output.

Given your examples, I'm not sure what you want--is it a boundary around the hypoxic area? 

Since you're averse to polylines, I'm guessing you want the boundary to be a raster because it's used for analytical purposes (since, cartographically/visually, it wouldn't matter).  Me, I'd use a polygon or polyline--which would allow me to clean it up (making for a better cartographic depiction), and if I needed to later I could always convert it back to a raster.

As for free base maps, use the File menu in ArcMap and choose: "Add data from Resource Center".  That will get you to everything ESRI has made available, and a few that other users have served.

All that said you can use the Contour List tool in the 3D Analyst to generate contour features. You can convert those features to graphics or rasters.


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