A geometric element defined by a pair of x,y coordinates.

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8
votes
7answers
6k views

Extract raster values at points

How can I extract values from a raster by points. I prefer not in Arcgis. I prefer in Qgis or Mapwindow or other open source gis.
11
votes
7answers
398 views

Public reprojection services

Are there any free public services where I can send one point in a coordsystem and it returns the point reprojected in a specified coordinate system? I will not be doing many requests, for now it is ...
3
votes
3answers
1k views

Is there a way to “disperse markers” across multiple point layers?

I have a bunch of point layers which often have overlapping features. The disperse markers geoprocessing tool works within a layer but is there a way to do it across more than one layer, so none of ...
2
votes
3answers
324 views

UK National Grid references and GeoDjango

Newbie question. I'm trying to insert some UK National Grid references into a Django PointField defined as follows: oscode = models.PointField(srid=27700, null=True, blank=True) My question is ...
17
votes
2answers
5k views

How can I find a point inside a polygon in PostGIS?

How can I find a point that is guaranteed to be within a given polygon in PostGIS? I am aware of the ST_Centroid function. However, the centroid is not always within a polygon, see below: ...
17
votes
9answers
10k views

How can I convert an excel file with x, y columns to a shapefile?

How can I convert an excel file with x, y columns to a point shapefile? There are some somewhat optional requirements in addition to the correct creation of a shapefile: Column types (as per ...
10
votes
4answers
763 views

Point Pattern Analysis Algorithms

I'm looking for point pattern analysis algorithms and literature on point pattern analysis, online resources and book titles welcome. The topics may range from general descriptions of algorithms to ...