geospatial

What would a minimal example for a choropleth map in Mathematica look like? I can read in a ESRI Shapefile using Import , but do not know how to work with the imported result. Graphics[ { ColorData["ThermometerColors"][ Rescale[CountryData[#, "GDPPerCapita"], {100, 50000}] ] /. HoldPattern[Blend[___]] -> Yellow, CountryData[#, "Polygon"] } & /@ CountryData[] ] And why the replacement? If there are no data of the required type for a given country CountryData returns Missing["NotAvailable"], causing ColorData , and its underlying Blend function not to return a specific RGB value. I replace this

Using geoDjango, what is the difference between myObj.objects.filter(point__dwithin(...etc.)) and myObj.objects.filter(point__distance_lt(...etc.)) ? Are they the same thing, or are they doing subtly different things? Ok, I did some research but I don't know if the results are of any use ;) I looked at the unit tests that they use to test the DB queries but they don't give real hints (to me). I tried to compare the generated SQL: I have already a geo application using a PostgreSQL databse. When I perform this query with __distance_lt : Place.objects.filter(location__distance_lt=(p.location, D

Is there a recommended way to make a custom query to mongodb using django nonrel? I have an entire site set up and running well, now I am just adding in some geospatial indexing and queries, and wanted to know if for geospatial queries there is already support or if there is a best practice way to do it using a custom made query? I found one answer to this question, let me now if there is a better one. As documented here assign your objects to the MongoDBManager - http://django-mongodb-engine.github.com/mongodb-engine/cool-stuff.html#included-mongodb-batteries from django_mongodb_engine

I'm trying to save the longitude/latitude of a location in my user Model and query it with $geoNear . I've looked at almost any page I could find on that topic, but still I'm not sure how to 1) create the model appropriately and how to query it. here's the part of my model: loc: { //type: 'Point', // see 1 //type: String, // see 2 coordinates: [Number], index: '2dsphere' // see 3 }, @1: According the documentation the type must be 'Point' if I want to store a point, but it throws TypeError: Undefined type `Point` at `loc` Did you try nesting Schemas? You can only nest using refs or arrays.

Has anyone implemented this, or know if it would be difficult to implement this/have any pointers? public static SpatialRelationCriterion IsWithinDistance(string propertyName, object anotherGeometry, double distance) { // TODO: Implement throw new NotImplementedException(); } from NHibernate.Spatial.Criterion.SpatialRestrictions I can use "where NHSP.Distance(PROPERTY, :point)" in hql. But want to combine this query with my existing Criteria query. for the moment I'm creating a rough polygon, and using criteria.Add(SpatialRestrictions.Intersects("PROPERTY", myPolygon)); EDIT Got a prototype

I have the following query: select distance(GeomFromText('POINT(8 49)',4326),GeomFromText('LINESTRING(8.329969 49.919323,8.330181 49.919468)',4326)) this gives me 0.97 degrees. But I need it in meters and do not know which SRID to transform to. Can somebody give me an example how to get the result in meters for spatialite? The positions are all in Europe. Just multiply the value in degrees by 111195 - this value is (Earth mean radius)*PI/180 - that is 'mean length of one great circle degree in meters on Earth's surface'. The result obtained using this method is within 1% of the geodesic

I have a collection of stores with a geospacial index on the location propery. What I am trying to do is given the user's latitude, latitude and a search radius (mi), I want to return the list of stores that are within those parameters. I saw the following example on the MongoDB documentation ( http://www.mongodb.org/display/DOCS/Geospatial+Indexing ), but it looks like the distance is in radians. center = [50, 50] radius = 10 db.places.find({"loc" : {"$within" : {"$center" : [center, radius]}}}) So, what is the formula to convert miles to radians? Solution The awesome people at mongodb-user

I have a table called 'flags' in a MySQL database with 400,000 rows. This table is made up of geospatial points that represent different positions around the UK. The application I'm creating uses Google Maps. On the map is a button that should toggle the flags visibility on the map. It's my job now to create an API that when passed a bounding box all flags inside the bounding box are returned (so that they can then be displayed on the map). The passed parameters are the North East latitude/longitude and the South West latitude/longitude of the viewport's current position. I now need to perform