Tagged Questions
3
votes
2answers
67 views
How to computational efficiently check if there are any overlapping polygons in a group of polygons?
I need to do some processing with groups of polygons. If any of the polygons in the group overlaps other polygon the result is unpredictable and don't throw any error. So, I need to detect if there is ...
0
votes
0answers
54 views
Fill polygon with colour depending on the value in MS SQL Server table
I'm using QGIS 1.8. Windows 7. I have a table in MS SQL Server 2008 R2 database with two fields: id and density(int). There are several polygons in QGIS. How can I set color of polygion depending on ...
0
votes
0answers
30 views
Slicing / Cutting a Polygon / Polygon List based on another geometry
I currently use GeoDjango (GEOS, GDAL, PROJ4), I have rather medium set of polygon data (buildings).
To streamline them to a client efficiently (client has a limited viewport) I only want to send the ...
2
votes
1answer
145 views
Create a square grid polygon shapefile with python
i have the following coordinates
minx,maxx,miny,maxy = 448262.080078, 450360.750122, 6262492.020081, 6262938.950073
i wish to create a square grid of size 1 m using python.
import math
...
6
votes
1answer
175 views
Efficiently identifying overlapping polygons with Python
I'm parsing the NOAA severe weather alert feed and using it as a datasource for a weather alerting system.
In the feed, I occasionally find a polygon entry for an alert. Unfortunately, counties that ...
3
votes
3answers
289 views
Python OGR: convert a point geometry into polygon
I'm writing a routine for creating the convex hull envelop around shapefiles of islands.
I could read the data, extract polygons vertices into a geometry and then compute the convex hull.
Now I need ...
0
votes
0answers
82 views
Regional statistics from a dataset (point inside a polygon aka region)
I am relatively new to GIS and I am trying to do some geographical analysis on same data I've collected. The dataset I have consists essentially in a file with the following format:
...
3
votes
2answers
122 views
How to filter out multipart polygons and then buffer?
I've written a small script trying to accomplish the task described in the question title. It basically looks like:
in_fc = '...' # Some shapefile goes here
# Get the fields (column names) of the ...
4
votes
1answer
279 views
Dissolving specific polygons inside SearchCursor with Python in Arcmap
I have a layer with catchment polygons. For those that are smaller than a certain size, I want to merge with an adjoining polygon (namely the one downstream). In the attribute table I have a GridID, ...
4
votes
5answers
284 views
Python loop Polygon to raster not working
I want to convert a large number of different shp polygons to raster in ArcGIS 10.1, using an existing field column "class" for the new raster classes. I am not very fluent in python but I thought ...
1
vote
0answers
78 views
How to construct a line from points in pyshp?
I am reading a shapefile for a pipeline and what I've noticed is that if I just draw a line from one point to the next (in the order I read them), there will be points where the line terminates, and ...
6
votes
1answer
193 views
How to draw shapes with highest possible decimal accuracy
I am trying to read input of lat and long to draw the shape based on condition.The input is standard array of lat and long with 15 decimal accuracy. I am realizing - I am loosing some decimal accuracy ...
5
votes
0answers
123 views
How to rotate polygon to find best fit in Mapnik? [closed]
I have a quite simple problem but somehow I just fail to solve it.
There is a polygon and a range xsize and ysize. The x and y size determines the mapnik generated image.
The polygon should now be ...
0
votes
0answers
93 views
python error when using polygon centroid tool [closed]
When I use the "Polygon Centroid" tool -- to fix labeling features on a shapefile...i get this "Python Error" with a bunch of coding I do not understand in a text box. Afterward QGIS 1.7 shuts down on ...
3
votes
1answer
277 views
how do I get the “outer mantle” of a polygon shape file? (without joining all the polygons)
I am interested in finding all the vertices of all polygons which are not on the inside the most outer polygoin that can be formed in a shape file:
Here is how I get all the vertices:
def ...
