Ask A Cartographer

Splined Text

November 09 2007 | 0 comments
Categories: ArcGIS Methods, Labeling, Maplex

How can I keep splined text created with ESRI's tool from 'breaking up' along the line. Letters
shift slightly along tight (or not so tight) curves and appear sloppy.

Mapping Center Answer:

There are a couple of things you can do. First, I’m guessing that you’re not using Maplex, which generally does a better job of creating smooth looking curved labels (that will get even better in version 9.3 which will go beta in the next couple of months). The ESRI Standard labeling engine’s bias in placing curved labels is that it was predominantly designed for street labeling and so it is very literal in interpreting geometry. The side-effect of that is that when you want to place a curved label on a stream line, which typically has a much higher density of vertexes, the spline has too many control points and essentially is a victim of the labeling engine trying to do too much.

Simplifying the lines that you need to label is the easiest way to get the labels to look better. I would recommend the Simplify Line tool (ArcInfo or ArcEditor license), using the Point Remove option. Then use these simplified lines just for label placement (don’t draw them; use a symbol with “No Color”). I recommended the Point Remove option because uses the Douglas-Peucker algorithm, which will not move vertexes, only remove them; which will dramatically reduce the chances that a label will be placed such that it intersects the line it is labeling.

That said, the example in the Simplify Line tools help file is hopelessly un-cartographic (and fails to illustrate key features of both algorithms). Don’t seek to make a radical change in the geometry, the idea is to remove 20-50% of the vertexes, not 75-90%.



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