2
votes
4answers
116 views

Best way to 'join' polygons

I'm looking for the best ways to 'group' a budge of block polygons in a new polygon that should be the town. My block layer is something like this: Or zoomed: And I'm looking to get something ...
1
vote
0answers
193 views

Convex Hull issue in QGIS 1.8

When creating convex hulls based on input field in qgis 1.8, there seems to be always one less convex hull created for the unique values in the input field. For example; I have a point vector file, ...
2
votes
2answers
148 views

Is there a way to visualize a convexhull in qgis 1.8 lisboa?

There is no way to visualize a convexhull in qgis 1.8 lisboa? I have tried following views in Postgis 1.5 I was told to use an id column to publish it in Qgis. If you not use an id column, u cannot ...
9
votes
2answers
414 views

How to build a minimum convex hull crossing the 180 degrees line?

I've been building convex hulls for species that inhabit the Indo-Pacific (~ from 20 to -65 degrees of longitude). The problem I've encountered is that for the species that can be found on both sides ...
6
votes
2answers
3k views

Converting point sets to polygon boundaries

I'm trying to convert sets of points to their respective polygon boundaries. I think this is something like a Voronoi diagram or Convex Hull, but not quite. I'm sure there's a technical term for it, ...
4
votes
2answers
461 views

Invalid Geometry Error after ST_ConvexHull

I've a Postgis table of around 80,000 points and want to be able to populate a second table summarizing the data with convex hulls based on points with a common attribute. For example, the data ...