spatial-index

While working on the simulation of particle interactions, I stumbled across grid indexing in Morton-order (Z-order)( Wikipedia link ) which is regarded to provide an efficient nearest neighbor cell search. The main reason that I've read is the almost sequential ordering of spatially close cells in memory. Being in the middle of a first implementation, I can not wrap my head around how to efficiently implement the algorithm for the nearest neighbors, especially in comparison to a basic uniform grid. Given a cell (x,y) it is trivial to obtain the 8 neighbor cell indices and compute the

I am new to the whole 'spatial index' thing, but it seems to be the best solution for filtering based on latitude/longitude. So I added a column to my table: So I created a geometry field: ALTER TABLE `addresses` ADD `point` POINT NOT NULL And then I tried to add an index: ALTER TABLE `addresses` ADD SPATIAL INDEX ( `point` ) But I get an error: #1416 - Cannot get geometry object from data you send to the GEOMETRY field What am I doing wrong here? jisaacstone OK I found the solution: Can't create a spatial index if some of the column fields contain no data. After running UPDATE `addresses` SET

I have +10k points (latitude, longitude) and I'm building an app that shows you the k nearest points to a user's location. I think this is a very common problem and I don't want to reinvent the wheel. I'm learning about Quadtrees. It seems to be a good approach to solve this spatial problem. I'm using these tools: Python 2.5 MySQL MongoDb Building the Quadtree is not that hard: http://donar.umiacs.umd.edu/quadtree/points/pointquad.html But once I've created the tree and saved it to a db (MySQL or MongoDb), how I run the query? I need to run queries like these: Find all points within 10 km of

Like most of the average PHP web developers I use MySql as a RDBMS. MySql (as other RDBMS also) offers SPATIAL INDEX features, but I'm don't get it very well. I have googled for it but didn't find clear real world examples to clarify my bad knowledge about it. Could someone explain me a little bit what is a SPATIAL INDEX and when should I use it? You can use a spatial index for indexing geo-objects - shapes. The spatial index makes it possible to efficiently search for objects that overlap in space Spatial Index is like an ordinary index with this difference that Spatial objects are not 1D

Here's my code: SET @poly = 'Polygon((-98.07697478272888 30.123832577126326, -98.07697478272888 30.535734310413392, -97.48302581787107 30.535734310413392, -97.48302581787107 30.123832577126326))'; SELECT name FROM county_shapes WHERE MBRContains(ST_GeomFromText(@poly), SHAPE); Whenever I run that I get a "MySQL: Invalid GIS data provided to function st_geometryfromtext" error. This returns the same error: SELECT name FROM county_shapes WHERE MBRContains(ST_GeomFromText('Polygon((-98.07697478272888 30.123832577126326, -98.07697478272888 30.535734310413392, -97.48302581787107 30.535734310413392,

Well, the question is clear enough. Is it possible to create spatial indexes using Entity Framework 6.1 fluent API? Short answer- No, it is not. I have seen this tangentially referenced throughout blogs and have found no concrete examples of implementation. It seems to be related to the fact that spatial indexes are filtered indexes, which are not supported in Entity Framework. As support for my answer I constructed a POC console app with the most recent version of Entity Framework (6.1). I took the following steps Created a model that had a property of the type DbGeography Enabled automatic

I found some open source R-Tree implementations in C#, but none with documentation nor signs of being used by someone else than the developer. Jader Dias The NetTopologySuite is a JTS port to C# and it contains a STRtree class which is a read-only R-Tree I know of none, but I would point out that libraries like this tend to: Get written (normally with some bugs). Bugs get ironed out though use. All active bugs are fixed Optional 'Latent' bugs which could never happen due to previous semantics of the platform on which the library operates crop up if the platform changes in some way. Thus lack