I need to display a map of the U.S. with states shown in different colors according to underlying data. I'd also like to have this map contain some facility for subscribing to hover/click events on each state in javascript, presumably using an imagemap. The data won't be changing in any kind of AJAX-y way, so ideally this component would...
I've always been intrigued by Map Routing, but I've never found any good introductory (or even advanced!) level writeups talking about it. Does anybody have any pointers, hints, etc? update: I'm primarily looking for pointer as to how a map system is implemented, data structures, algorithms, etc. ...
Given a latitude and longitude, what is the easiest way to find the name of the city and the US zip code of that location. (This is similar to http://stackoverflow.com/questions/23572/latitude-longitude-database, except I want to convert in the opposite direction.) Related question: http://stackoverflow.com/questions/158557/get-stree...
In postgis, is the "ST_GeomFromText" call very expensive? I ask mostly because I have a frequently called query that attempts to find the point that is nearest another point that matches some criteria, and which is also within a certain distance of that other point, and the way I currently wrote it, it's doing the same ST_GeomFromText t...
I need to convert latitude/longitude coordinates into Easting/Northing coordinates in the Alberta 10 TM Projection. The 10 TM projection is similar to UTM, but it is a custom projection for the province of Alberta, Canada. I think (with some effort) I could code it myself but would rather not reinvent the wheel if it's been done alread...
I have the situation where i use GIS software which stores the information about GIS objects into separate database table for each type/class of GIS object (road, river, building, sea, ...) and keeps the metadata table in which it stores info about the class name and its DB table. Those GIS objects of different classes share some parame...
How do I take a set of polygons which contain arbitrary values and create a corresponding bitmap where each pixel contains the value of the polygon at that location? To put the question into context, my polygons contain information about the average number of people per square kilometre within the polygon. I need to create a raster/bitm...
I have a number of tracks recorded by a GPS, which more formally can be described as a number of line strings. Now, some of the recorded tracks might be recordings of the same route, but because of inaccurasies in the GPS system, the fact that the recordings were made on separate occasions and that they might have been recorded travelli...
Has anybody created a nice wrapper around Yahoo's geo webservice "GeoPlanet" yet? ...
I'm looking for a webpage or some other resource that provides a very basic introduction to SQL queries. I'm teaching a class on Geographic Information Systems and I'd like to go into a bit more depth on SQL than the textbook does, but I still want a written resource that I can point the students to. Most of the class are not computer ...
Having a set of (2D) points from a GIS file (a city map), I need to generate the polygon that defines the 'contour' for that map (its boundary). Its input parameters would be the points set and a 'maximum edge length'. It would then output the corresponding (probably non-convex) polygon. The best solution I found so far was to generate ...
Hi, I have 1 red polygon say and 50 randomly placed blue polygons - they are situated in geographical 2D space. What is the quickest/speediest algorithim to find the the shortest distance between a red polygon and its nearest blue polygon? Bear in mind that it is not a simple case of taking the points that make up the vertices of the ...
I'm thinking about making a simple map control in WPF, and am thinking about the design of the basic map interface and am wondering if anyone has some good advice for this. What I'm thinking of is using a ScrollViewer (sans scroll bars) as my "view port" and then stacking everything up on top of a canvas. From Z-Index=0 up, I'm think...
I've got a CSV file containing latitude and longitude values, such as: "25°36'55.57""E","45°39'12.52""N" Anyone have a quick and simple piece of C# code to convert this to double values? Thanks ...
I know of the US GIS TIGER file format from years ago, but have never used it. I'm very shortly going to need to very quickly implement simple geocoding and vector graphics of roads and other features. Where do I go for information - are there tutorials, example queries, etc? Are there other ways to include geocoding and basic mappi...
I'm using a lat/long SRID in my PostGIS database (-4326). I would like to find the nearest points to a given point in an efficient manner. I tried doing an ORDER BY ST_Distance(point, ST_GeomFromText(?,-4326)) which gives me ok results in the lower 48 states, but up in Alaska it gives me garbage. Is there a way to do real distan...
I'm look for a GIS/Mapping tool that will give me easy SERVER-SIDE access to route information (specifically, trip time and distance) in an ASP.NET web application. From what I can tell, Google and Yahoo maps do everything client-side in javascript, but neither provide services to retrieve just the route information. I'm interested in b...
If I have a series of points as longitude and latitude, how would I calculate the center of all of those points? ...
When I download the zip file from the website it contains files with the following extensions: .dbf .prj .sbn .sbx .shp .shp.xml .shx Is this is a common data file format that I download or purchase a converter? I think this is some kind of mapping data file but I all need are the addresses it contains to push into our existing databas...
I've seen that it's possible to get the latitude and longitude (geocoding, like in Google Maps API) from a street address, but is it possible to do the reverse and get the street address when you know what the lat/long already is? The application would be an iPhone app (and why the app already knows lat/long), so anything from a web ser...