Datasets for Proportional Symbol Maps
Posted 12 October 2010 - 05:29 PM
I'm looking for public available datasets for proportional symbol maps. These sets should contain latitude and longitude as well as a measured quantity. Examples of such data would be Earthquake occurrence and population of countries/states/cities.
I've already find some:
A wide range of statistics:
Earthquakes and Tsunamis:
I'd like to hear from the more experienced, if they know other freely available datasets (specially worldwide) to share.
Thank you very much!
Posted 13 October 2010 - 02:29 AM
Posted 14 October 2010 - 07:37 AM
I absolutely agree with Frax.
Hi, maybe it is a language issue - but keep in mind that proportional symbols are part of the presentation/map part - the datasets don't have anything inherent regarding the representation.
And to illustrate the concept, I have taken a dataset with polygon feature class defining the boundary of each constituency of few Indian cities. Then I added the area field in the attribute table, populating it by calculating the geometry. Now I use the area quantity to create ten different classes to be colored with gradient color (darker signifies larger area, one can use other attributes, like the population, precipitation, temperature, almost any measureable quantity.
Then I use larger font for larger areas, also I know that larger areas are darker so I use lighter color for larger fonts. So all this is how you utilise the data for presentation. One can use the quantity data for generating gradually larger symbols, a very common and built in approach with almost all GIS packages.
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