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Visualizing attributes (quantity and time stamp) with one symbol

October 19 2011 | 2 comments
Categories: Symbology

Hello. My question is about visualizing multiple attributes in one symbol.

I have a set of geographic points. In addition to lat/long corrdinates, each point has two other attribues -- QUANTITY (i.e., the amount of pollutant at that point measured in milligrams) and a TIME stamp (the date m/d/y when that sample was collected -- which was converted into the number of days relative to a fixed time point).

I want to visualize both attributes simultaneously -- pollutant QUANTITY (as circles whose diameters are proportional to pollutant quantity) and TIME (as a different shade of grey based on when the sample was collected relative to an initial start date).

When I try to accomplish this task with the multiple attributes function,the QUANTITY is corretly displayed as proportional symbols. However, the TIME variable refuses to follow the graduated color pattern. Thus, the circles have the correct size (QUANTITY) but are labeled with the incorrect color (TIME).

Using ArcInfo 9.3. I'd appreciate any insights you could please share. Thank you.

Mapping Center Answer:

We have gotten this question before. Our Multiple Attributes renderer only works for one qualitative + one quantitative attribute, not two quantitative attributes. Nonetheless, here is how you can do this:

Group and rank data for symbololgy control posted by Craig Poynter on Oct 25 2011 2:19PM
Could you add a new field and rank your data and then symbolise based on the new ranking field (e.g. 100mg 1 day = 1, 100mg 2 days = 2, etc.). Then you could select like quantities (e.g. quantity in milligrams) to size your symbol, but also colour then independently based on time.
feedback posted by Kenneth Field on Oct 25 2011 2:42PM
Yes, that would work but of course it depends on the complexity of your data which could create a huge variety of different symbols to individually specify.

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