Carto Representations in double line drainages
I am creating carto reps that meet the FGDC Geologic Map Standard.
I have reached a road block when trying to create the rep for rapids/waterfalls on a double line drainage. The symbols are 30.3.28 and 30.3.26, on page A-30-5 of FGDC-STD-013-2006.
Also, the outline for glaciers (30.2.45) requires the pattern to be "rotated perpendicular to the glacial trend". Is there a way to accomplish this without manually entering each angle?
Mapping Center Answer:
There is no way that we have found (yet) to automate a solution to this problem (Here is a link to the PDF showing the standard).
The way we have accomplished this effect in the past is to create a polygon feature representing the falls, rapids, or other similar feature that crosses fully or partially the river/stream and then manually assign an angle that looks best.
One of the reasons this solution is difficult to automate is because of the nature of the shape of the river/stream polygon (what the USGS also calls a double-line stream) and that the falls or other feature occur at a specific locations on a polygon water feature that could be fairly straight, or very sinuous, or multi-part (imagine an island interrupting the falls).
So, while you could use representations to accomplish this work, it's just as easy to do so without.
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