Yesterday, I used a theme to annotate the map (and somehow tonight I destroyed that post- I will redo it later- so sorry!)  Today, we will apply that same idea to automatically color some polylines representing road centerlines. This is the same technique I used in my AU class to automatically hatch my final overlay topology. Grab the paper here and watch the screencast here.

Find out more after the jump.

First, you will go through all of the same steps from yesterday’s post (which you can’t see because I screwed up and destroyed the post- I will redo later- so sorry), but stop here:

Decide how you would like to theme your road centerlines (or parcels or whatever). Do you want each line a different color? Do you want all segments of the same road name to be the same color? All soil boundaries of the same type to be the same color?

I’m going to theme the map so that longer roads have a different color than shorter roads.

Remember- length is an AutoCAD property under PROPERTIES.

Back in the Range of Values box, press “Read Data”, then “Find Ranges”. Customize these ranges if you’d like.

Back in the Thematic Mapping dialog, check the color box an select a Ramp. Check “Scale to fit”. This changes the colors of lines/polylines. If you are dealing with closed polylines and would like a color fill, scroll over to the Hatch column and do the same thing.

Press Done and check out your map.

Hopefully this gets you thinking. Check out the tutorials, AU Classes and Help for more ideas about adding legends and other advanced techniques.