Tagged Questions

7
votes
1answer
137 views

Is there a significantly faster way to buffer than arcmap?

I hope this question is appropriate here and I apologize if it is more of a discussion question than a specific technical problem. I have to buffer 150,000 polygons for a real estate project. While ...
2
votes
1answer
52 views

point of intersection issues

I have a table containing a set of points of intersections. Most of the roads intersects whith just one road BUT i have some roads which intersects with two, therefore three different point of ...
4
votes
1answer
691 views

Performing Geoprocessing SQL Queries in QGIS from a PostGIS Database

This may be a dumb question, but is there way to run a PostGIS geoprocessing SQL query in QGIS? Specifically, I am thinking of running SQLs such as ST_Union, ST_Split etc etc. I have tried the ...
5
votes
2answers
323 views

Reduce Tracking Data Set

I'm building an application that uses data from GPS units on board vehicles and displays it on a map. A lat/long is recorded every .5 seconds and a session can be many hours... this can add up to be a ...
11
votes
4answers
1k views

PostGIS: Select features that do NOT intersect

This seems to me like such a simple question (and it probably is) yet I cannot seem to find an example that gives me the answer. Using PostGIS, I just want to select points that fall outside of ...
5
votes
1answer
267 views

Postgres/postgis cursors

I have a road network with StreetName and min/max address ranges for each segment (ie- StreetName = 'Main St', Min = 100, Max = 199). I also have individual address points with similar information ...
8
votes
6answers
405 views

PostGIS: Assign ID of point in layer A to closest point in Layer B

This should have been an obvious precursor (that I didn't ask) to my other question: PostGIS function to create spider diagrams? If I do not know the relationship between a point in layer A (stores) ...
5
votes
3answers
917 views

How to create spider diagrams (hub lines) in PostGIS?

I'm rather new to PostGIS but I have done a lot of reading. One thing that I have been searching for is a function that allows users to create a "spider diagram" (also called "desire lines" or "hub ...
9
votes
2answers
2k views

How to import esri Personal Geodatabase (.mdb) to PostGIS on Linux

We have esri Personal Geodatabases that we need to import into PostGIS. Ultimately, we'd like to allow people to upload an MDB on a web server, and have it import the layers into PostGIS. On ...
11
votes
4answers
2k views

Simplifying adjacent polygons

I encountered a problem simplifying set of polygons that are adjacent. If I simplify each polygon separately with the Douglas–Peucker algorithm (which is used by many open source tools), the resulting ...
10
votes
4answers
2k views

Simplifying polygons to linestring

I would like to simplify some polygons that represent rivers into linestrings. I assume that holes in polygons can be omitted. Anybody has some good idea how to simply do it? It would be nice, if it ...