0
votes
0answers
21 views

How do I break up a shape file into contiguous area?

I've got a shapefile which is a union of non-contiguous shapes. I'd like to be able to break them up into individual groups. For example, suppose I have a polygon of the entire US, currently only ...
7
votes
2answers
252 views

How to check if points are within a circular sector using PostGIS?

I want to get the stars within the black region as shown above. To find this I have the centre of circle (lat, long), radius and the angle of region (45 degree). I am new to postgres. I worked on ...
3
votes
2answers
155 views

geospatial libraries like postgis

I'm pretty comfortable with postgis, but I realized that for part of my application, having a database is pretty heavy. I'd like to be able to take a stream of Point objects and check against an in ...
2
votes
3answers
205 views

Best Approach to display charts on a web map?

I have a very basic understanding of GIS through some basic work with openlayers in Drupal CMS. I am trying to understand what is the best approach to display a chart on a map (like the one below)? I ...
1
vote
2answers
324 views

Function for Selecting Points in a Polygon

I've been banging on this for a few hours, but since I'm relatively new to PostgreSQL and PostGIS, I can't find the solution. I'm trying to create a stored procedure (function) which will return all ...
0
votes
1answer
290 views

How to get points in bounding box by degrees for map

I have some concerns about working of BOX3D PostGIS function. I tried to find places in square -158.721365889063 66.09275164148659, 154.608712235937 52.56807548751039(degrees). But this where ...
6
votes
4answers
2k views

Point in polygon algorithm for multiple polygons

I've a Google map with bunch of polygons on it. Here is a problem I'm interested in: Given a lat,lng point, what's the best way to determine all the polygons that this point lies in? The obvious way ...
4
votes
1answer
2k views

Why is my PostGIS query not using a spatial index?

I am having an issue with a spatial query that is not making use of indexes. My schema is: CREATE TABLE geoplanet_place ( woeid integer NOT NULL, "name" character varying(300) NOT NULL, ...