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Working with Streamlines

April 24 2009 | 2 comments
Categories: Symbology

I'm modeling winds over terrain in Patagonia, and I need to do maps with windstreams. I can export the streamlines from CFD Software (ANSYS), and I can import them into ArcGIS.

¿How I can represent in ArcGIS a line with a color that is dependent of the variable along it? (Windspeed for example).

Mapping Center Answer:

The answer to this question depends on whether you want to symbolize the line to show a quantitative or a qualitative variable. If you want to show a qualitative variable (one that relates to type or kind, not a numerical value), then you can use the Categories – Unique Values renderer:

I used this approach in the example below showing warm and cold ocean currents:

If you want to show a quantitative variable (one that relays a magnitude message), then you can use the Quantities – Graduated Symbol renderer:

I used this approach in the example below showing the length of ocean currents:

Alternatively, you could use the Quantities – Graduated Color renderer:

But you can see that it will be harder for your map readers to distinguish these categories than if you used size to show the variation in magnitudes.

OK, of course, but not enough to my... posted by Aiego Vallmitjana on Apr 28 2009 3:25PM
And really, thanks for the answer... but I´m trying to represent 3D streamlines (not 2D) painted with a color that represents a quantity (speed in this case). The question is, can a single line (not segments) be represented in this way? How?
No and Yes posted by Charlie Frye on Apr 28 2009 6:14PM
No, there is not a symbology method that changes the color of a line, along the line as it draws. But...

Yes, there are a couple of ways to approach modeling data to support using existing symbology methods. First is that you break the features into smaller features each representing a classed range of velocities, or whatever is being measured along the line. An example would be stream flow on stream/river lines, where each segment in the network is augmented by the upstream inflow, plus it's own drainage.

You could also use dynamic segmentation (aka linear referencing):

http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?id=6617&pid=6615&topicname=Dynamic_segmentation

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