3

I have a QGIS project with a shapefile (CRS:WGS84) overlayed on a googlemaps satellite layer. My shapefile consists of many GPS coordinate points measured in decimal degrees, and another field for accuracy of the GPS reading, measured in meters. I want to create a variable distance buffer around the points so that each point has a buffer the size of the respective accuracy reading. For example if a specific point has an accuracy reading of 6.0 meters, I want a 6.0 meter buffer around that point.

I've tried creating a variable distance buffer normally but it renders totally off. I think this is probably due to the lat/long an CRS being set for decimal degrees, but the accuracy measurement in meters. However I have no easy way of transforming that accuracy into decimal degrees without transforming the entire map.

Is there a way to create a variable distance buffer in meters around points in decimal degrees?

PolyGeo
  • 65,136
  • 29
  • 109
  • 338
Liz
  • 31
  • 2
  • Can you describe a little more about the spatial extent of the dataset? Is it global or local for example? – SaultDon Mar 29 '17 at 18:29
  • The extent is global, otherwise I think I would just reproject to a different CRS. – Liz Mar 29 '17 at 18:43
  • There's an answer to another question that has a couple options you can consider - have a peek at http://gis.stackexchange.com/a/107009/1297 – SaultDon Mar 29 '17 at 18:45
  • What if you split the point file into multiple shapefiles based on buffer size categories and create a fixed-distance buffer for each one? – csk Mar 29 '17 at 19:34
  • @SaultDon, thanks, I saw that response and tried to use pseudo mercator EPSG:3857 for the whole project like suggested but that put my points way off of the googlemaps satellite image. – Liz Mar 29 '17 at 20:08
  • @csk that would probably work, but I have thousands of points, and more coming in everyday so I would rather not have to sort through them all and create hundreds of shapefiles for groupings, and have to repeat as new ones come in. Thanks though! – Liz Mar 29 '17 at 20:10
  • Also, when I tried just using a UTM CRS for a local portion to test, it looks like the buffer created around the entire shapefile (points at the center of several concentric circles), not around individual points. Am I just doing something super obvious wrong? – Liz Mar 29 '17 at 20:13
  • Try adding a screenshot of the settings you're using in the buffer tool. If you're making an obvious mistake, maybe someone here will be able to spot it. – csk Mar 31 '17 at 19:31

0 Answers0