It's called a choropleth map.
http://oobrien.com/2010/01/simple-choropleth-maps-in-quantum-gis/ is one
tutorial I found.
Jim
On August 1, 2016 8:07:11 PM EDT, Chuck Young wrote:
>Thanks Jim! You are right a join! I now need to know how to get the
>data
>to show the density by varying colors depending on the density. I know
>it
>must be fairly simple bit I just don't have the key to it in my mind.
>Somethimes it can be rigth in front of me but I don't see it. So an
>example mite be good if anyone has a place in the manual or tutorial to
>point me to.
>Thanks again!
>Chuck
>
>On Mon, Aug 1, 2016 at 4:53 PM, James Keener wrote:
>
>> Beyond just PostGIS, postgresql is a much better database on most
>fronts
>> than mysql.
>>
>> If you have two tables, one with geometries and one with densities,
>they
>> both need to have the same id somewhere. Once you have the join key,
>you
>> can perform a join , not a union, to get a result set containing both
>the
>> geometry and the density. You can use raw SQL in qgis, but I tend to
>create
>> a view in the database based on the query and the qgis will treat
>that as a
>> table, more or less.
>>
>> Jim
>>
>> On August 1, 2016 7:35:18 PM EDT, Chuck Young
>wrote:
>>
>>> I have been using databases for years and have used QGIS since 1.8
>for
>>> general mapping. I know it can use additional data attached to the
>>> geographic data via a union query to display lots of different
>things. I
>>> have map areas where population density would be nice to display
>using
>>> different background fill colors bases on that density. I just need
>a bit
>>> of a boost getting the idea as to how to start and which way to go.
>>>
>>> I have been using the program with SpatiaLite database. Do I need
>to go
>>> tto the PostGis db? Most of my other data is currently in MySQL.
>>>
>>> Thanks for amy advice / guidance!!
>>>
>>> Chuck
>>>
>>> --
>>>
>>> Qgis-user mailing list
>>> Qgis-user@lists.osgeo.org
>>> List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
>>> Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
>>>
>>>
>> --
>> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>>
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.___
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
