Linked Questions

0 votes
1 answer
139 views

Measuring roundness using buffers around centroids [duplicate]

I'm trying to measure the compactness (roundness) of some 800 polygons of different shape and size. I created the centroids and what I want to do now is to buffer those centroids with the exact same ...
1buzz's user avatar
  • 145
14 votes
7 answers
11k views

Calculating maximum distance within polygon in x-direction (east-west direction) in PostGIS?

I am interested in the maximum width of a polygon e.g. a lake, in east-west direction. Bounding boxes will help only in simple polygons but not in complex concave polygons.
cardiopteris's user avatar
8 votes
6 answers
5k views

Creating polygons as % of original area using ArcGIS Desktop?

I have a polygon shapefile and need to create new polygons, within the originals, as % of original area. I used buffer by field (Field= new area as %) but the buffers are created in circles around ...
A_Y's user avatar
  • 81
6 votes
5 answers
409 views

Is there any way to differentiate and select polygons according to their shape on SpatiaLite/PostGIS?

I have this small SpatiaLite database and it looks like the following: It's made of polygons and I'd like to find a way of excluding all polygons that look more like a line. Something like excluding ...
raylight's user avatar
  • 1,241
14 votes
2 answers
1k views

Detecting branched polygon shape?

I have a vector layer with millions of polygons making continuous coverage. I need to classify them according to their shape. I am already using several shape indexes from landscape ecology like ...
nadya's user avatar
  • 2,481
11 votes
1 answer
1k views

Determine roundness of polygon in QGIS

Suppose a polygon layer in QGIS with differently shaped polygons (no multi-geometries, let's keep it simple). Is there a way to calculate some kind of roundness characteristic of the individual ...
thymaro's user avatar
  • 505
3 votes
1 answer
1k views

Decreasing polygon size based on percentage using ArcPy?

I would like to decrease the size of polygons by percentage and not by distance in order to implement this into ModelBuilder to loop over a number of polygons. To my knowledge this tool is available ...
Daniel's user avatar
  • 67
2 votes
3 answers
322 views

Georeferencing a large set of points

I have a static image of a map: And I would like to obtain the coordinates of each blue point. I am very new to QGIS but I have done a very similar task but for a much smaller set of point. My ...
BenBernke's user avatar
1 vote
1 answer
126 views

Create polygon of fixed area based on cost/friction surface [closed]

I am using ArcGIS Desktop 10.4 and have all extensions. I have a shapefile of 494 points. I also have a cost surface/friction surface raster. I want to create a polygon of 13.4 hectares around each ...
user131981's user avatar
0 votes
0 answers
64 views

Filter long shaped polygons

I have a PostGIS database with a layer of 60k polygons, some of them erroneous. These erroneous polygons are extremely narrow, long shaped. Maybe I can best describe them as 'Needle' shaped polygons. ...
GIStrees's user avatar
  • 119