Optimisation is the act of making things as good as possible with regard to some criterion, eg. more efficient, faster or slimmer.

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17
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6answers
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Ways to Speed Up Python Scripts Running As ArcGIS Tools

This is a pretty general question. I just wondering what tips and tricks GIS programmers have used to speed up arcpy scripts that you import into the toolbox and run. I work most everyday writing ...
7
votes
3answers
2k views

how to find 20 closest points efficiently

Say I want to find 20 closest business near me. My table structure is like this: BusinessID varchar(250) utf8_unicode_ci No None Browse distinct values Change Drop ...
19
votes
2answers
5k views

Looking for fastest solution for Point in Polygon analysis of 200 million points

Apologies for asking a question that has been asked before -- I've read through answers, and I'm left wondering how to implement the recommendations. I've never used SQL, Python, C, and have only ...
8
votes
2answers
2k views

How can I more efficiently select related records?

Below is the code I'm using to replicate the "related tables" button in ArcMap. In ArcMap that button selects features in one feature class or table based on the selection of features in another ...
6
votes
5answers
1k views

Effectively displaying a large amount of data on Google Maps APi

I have about 20 layers that I'd like to put on a Google maps API. I assume I'll need some form of a tile cache server and perhaps under mapserver or geoserver. These layers amount to about 400mb so ...
4
votes
3answers
453 views

How to efficiently find points within an elliptical area?

Using PostGIS 2.0.0 I need to filter the results of a function, which returns many POINTs, to find the ones that lie within an elliptical area defined by two points and a distance (all parameters ...
22
votes
5answers
8k views

Optimizing osm2pgsql imports for OSM data

I'm currently building an instance on EC2 on which to import the entire Planet.osm snapshot of the whole Earth's worth of data for some projects we're working on. I've spun up a large Ubuntu x64 ...
8
votes
4answers
1k views

Fastest spatial storage format?

I am wondering what storage method will result in the fastest reading of the map vectors for rendering. SHP? PostGres? SQLite? (They do not change often and I do not need spatial functions for these ...
6
votes
4answers
3k views

ST_Intersection slow query

I am trying to perform an intersection between two layers: Polyline layer representing some roads (~5500 rows) Polygon layer representing irregularly shaped buffers around various points of interest ...
8
votes
4answers
1k views

Performance of google map tile creation processes

I know that question is rather vague but please bear w/me. I'm trying to get an idea of what sort of product performance - specifically timing - people have seen for various methodologies they have ...
10
votes
1answer
331 views

Are there any intelligent travelling salesmen?

Jokes aside, I have had a routing problem that is almost a travelling salesman problem (TSP): the starting point is defined the end point coincides with the starting point each node has to be ...
6
votes
1answer
1k views

Performance Gain Through GIST Index for Point in Polygon Query

I have two tables: locations(id,region_id,the_geom) and regions(id,the_geom). For each location point I want to determine the region it is located in: UPDATE locations SET region_id = (SELECT id ...
4
votes
1answer
124 views

Which spatial bundling or grouping algorithm optimally groups elements by attribute?

As I delve deeper into GIS, I find myself trying to improve efficiencies of certain procedures and processes. The one process I'm working on now is spatially scheduling construction projects. For ...
4
votes
1answer
243 views

geodjango slowness and debugging

I'm using geodjango + postgres to display polygons from tigerline on a map. Pretty simple stuff so far. My issue is that when I use the GPolygon object: django.contrib.gis.maps.google.GPolygon there ...
4
votes
3answers
4k views

How to fix performance problem in PostGIS ST_Intersects?

I'm a newbie in postgis and I have a problem in query performance. This my query: SELECT DISTINCT ON (userid) userid ,ST_AsText(position), timestamp FROM table1 WHERE ST_Intersects ( ...
3
votes
1answer
50 views

Coordinate conversion (EPSG:3857 to EPSG:4326) using OpenGIS/JTS too slow

I am using the Java based libraries of OpenGIS and JTS to convert coordinates from EPSG:3857 to EPSG:4326 to proceed to compute the distance using the Haversine formula. The distance features in a ...
2
votes
1answer
539 views

How to speed up this simple MySQL points in the box query

MySQL doesn't have nearest neighbor search so. So I try to come up with a "distance" that's reasonable so the number of returned query is around 20-200. That way innodb doesn't have to compute ...
2
votes
3answers
208 views

Looking for TSP with Target different from Source

I know the TSP (traveling sales person) in osm2po is beta but it works quite well. Is there a way to designate a final target location that is different from the initial source location. In other ...