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wavy lines symbology

July 03 2008 | 0 comments
Categories: Cartographic Representations, Symbology

How do I create a line symbol that produces a wavy line? I have used a marker and rotated it to create the desired effect, but this is less than satisfactory. Such a method often produces breaks in the line by a marker that seems to not rotate. The effect I am trying to mimic is the base flood elevation on the FEMA DFIRM maps.

Mapping Center Answer:

I used the FEMA DFIRM specification found here: http://www.fema.gov/library/viewRecord.do?id=2206

and specifically used Appendix K, page 65.

That symbol is one of those symbols that looks great in the legend because the short line is horizontal, so it's easy to display. In practice this is one of the hardest symbols to render on a compute.

I did some experimenting and found a way to get a pretty decent result--at least more so than one could have achieved prior to cartographic representations.

Essentially this line is comprised of a roughly L shaped marker symbol that is rotated about 135 degrees. So what I did was to convert my layer, with it's default symbol to representations. (I had a line layer) Next I removed the line stoke symbol layer and replaced it with a marker layer.

With that marker layer I first clicked on the marker symbol and then Properties in the Representation Marker Selector. Then I selected and deleted the default symbol. I used the Create Polygon tool and created that rough looking L symbol, but I drew it in it's rotated form so I wouldn't need to have ArcMap use extra CPU cycles to rotate it. Once I had a decent rotated L, I clicked OK on both of my dialogs until I was back to Layer Properties. Note, I rounded the corners of my "L"marker to make them look a bit more like a wave:

Marker Editor to show position of L relative to center of markerMarker Editor to show position of L relative to center of markernter of marker

I set the size to 9, and then the Step to 8.5--that forced the symbol to overlap a little bit to preserve the connected look. Then I set the Endings to be with a Marker. Last, I added the smooth curve geometric Effect (click the "+" button); I played with the flat tolerance setting a bit until I had cleaned up most of the gaps and overshoots. There are a few bad areas, but what you're looking at are streets, and I expect your flood zone polygons won't criss-cross so much.

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