topic User defined map service symbology by feature attribute in ArcGIS Viewer for Flex Questions

User defined map service symbology by feature attribute

MikeHouts — Fri, 21 Sep 2012 14:26:26 GMT

I am working in Arc10.1 with the latest flex service and have question about dynamic may symbology. I have a several polygon layers that are very large (100k+ polygons) and want to display the same polygon file based on different attributes. Since the polygon files are large, I would like to avoid loading them as a separate.redundant service for each display option, but rater let the user define what attribute a pre-set color scheme was applied to. For example, imagine a U.S. states layer with population, mean income, temperature and rainfall as attributes. Instead of loading the states layer 4 times (for each individual attribute/symbology) I am interested in finding a way have only one copy of the polygon file loaded and let the user identify/change what attribute to base the symbology on. Is this possible?

Thanks, Mike

Re: User defined map service symbology by feature attribute

ChristopherBlinn1 — Fri, 21 Sep 2012 17:10:33 GMT

Mike,

If I understand everything correctly, you are just wanting to symbolize a service differently based on different queries, am I correct?

If so, you could approach this by creating the interface where users define what attribute they want to symbolize on. Say a drop down menu with your examples, population, income, etc.

Once the selection is made, this would fire a query task which obtains the feature set from the service. The query task contains a query which selects where your layer field values meet a condition. You can then have a graphics layer be populated by the return feature set of the query.

The symbology or style of the graphics layer can be based on the query that was used. This would take some work if you are wanting some complex symbology but achievable nonetheless.

Simply put that is one direction for accomplishing such task.

I understand you do not want to load the same file multiple times, but does it necessary have to be dynamic? Caching the service would allow faster drawing. If your attributes are updated all the time, then this would not be a very good option, but if they do not then maybe it would help. Then users can then just select what they want to see and it will draw. With some simply scripting, you could even force only one service to be on at a time.

Hope this helps.

Best,
Chris B.

Re: User defined map service symbology by feature attribute

MikeHouts — Mon, 24 Sep 2012 16:59:48 GMT

Thanks Chris,

This is kind of what Im aiming for, but it not so much a value that Im wanting to search for to symbolize, but rather change symbology by data themes within a polygons attribute columns. So the first part of selecting a field is right on, then I just need some script or a widget to load a layer file that corresponds to that attribute/theme. Im not good with scripting, so was kind of hoping to find something.

Mike