2

I'm attempting to map cell phone towers and their range in QGIS. I'm wondering if it's possible to create buffers which change color intensity according to their distance from a central point. The buffer color is most intense at the center and gradually becomes lighter as one moves away from the center.

I speculate that I must copy the range of each tower to the buffer layer attribute table and then select "Graduated" in the style menu of the buffer. Unfortunately, the buffer layer has only 1 row in its attribute table.

Are there other solutions?

PolyGeo
  • 65,136
  • 29
  • 109
  • 338
user35310
  • 23
  • 3
  • Are you doing "buffer by a field" in QGIS? Meaning each of your input points (towers) has a value for their range or distance? If so, when you create those buffers, they should all carry the input distance value used to create the individual buffers. From there, all you have to do is symbolize the buffer polygons by that distance value, choose the colours you want to use, and voila... – DPSSpatial_BoycottingGISSE Aug 01 '14 at 17:29
  • This was my initial thought. However, the buffer layer has only 1 row with all fields set to "NULL". – user35310 Aug 01 '14 at 17:36
  • I just tested using 'buffer by field' using QGIS 2.4 and the attributes are there for each of the input points... – DPSSpatial_BoycottingGISSE Aug 01 '14 at 18:32

1 Answers1

0

It sounds like you are just trying to simulate the effect of the signal intensity or coverage right?

For a visual effect, you can use the "shapeburst" type of fill on the buffer.

Shapeburst does a kind of euclidean distance that respects the shape of the feature it's being applied to.

Open up the properties window for the buffer, then select the Symbology tab. It should be set to Single Symbol at the top pull down menu. Then you can click the feature below Fill, and then you should see a pull down menu in the top right of the window that you can change to Shapeburst Fill.

There are lots of options for the Shapeburst Fill that allow you to shade the entire feature or a set distance. There is even a nice blurring feature that makes it look really nice.

But you'll need to upgrade to QGIS 2.4 which is where this feature was introduced.

There is a blog entry by Nyall Dawson exploring some of the options for Shapeburst Fill styles in QGIS 2.4.

SaultDon
  • 10,389
  • 1
  • 43
  • 78