Esri Mapping Center - Ask a Cartographer

Representation, marker fill, random inside and RANDOM ROTATE

November 09 2009 | 2 comments
Categories: Symbology

I would like to create a polygon representation rule, with a marker symbol randomly distributed inside the polygon (no problem so far), the difficult part is to place each marker symbol with a randomly assigned rotation. (See attachment for what I want to accomplish). There is a geometric effect for rotation, but I cannot find a way to make the rotation random.

Mapping Center Answer:

There is no Random option for the rotation so you should add a new field to the attribute table that includes a random value from 0-360 and use that field to set the random rotation for the markers. Take a look at this Help doc about random number generators. Here is the online help for rotating point features using cartographic representations.

Attachment: Rotation sample

The question was about random fill posted by Niklas Norrthon on Nov 9 2009 10:48PM

The proposed workaround will not work since the question is about random fill. Each feature is a polygon with markers randomly distributed inside, so there is no field that will affect each marker individually.

Random points posted by Aileen Buckley on Nov 10 2009 5:16PM

You could generate random points within the polygon, then assign the random angle attribute value and it will still work. Here is the help topic on how to crete random points within a polygon feature class: http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?id=1783&pid=1777&topicname=Create_Random_Points_(Data_Management).

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