Optimisation is the act of making things as good as possible with regard to some criterion, eg. more efficient, faster or slimmer.
2
votes
2answers
36 views
PostGIS - ST_Collect but only include POLYGONs not POINTs?
In PostGSI, is there anyway to turn a GEOMETRYCOLLECTION into a MULTIPOLYGON by dropping all non-POLYGONs/non-MULTIPOLYGONs?
I'm doing a query that cuts a bunch of geometries (using ST_Intersection) ...
1
vote
0answers
48 views
Covering a Polygon with Minimum number of circles with fixed locations
In QGIS, I have a vector polygon of a fixed size and shape. I also have a set of circles of a fixed radius and fixed location, which cover part of the polygon. What I would like to do is remove as ...
3
votes
1answer
181 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 ...
4
votes
2answers
138 views
How do I reduce the number of drawn polygons on an Android Map?
We're using spatialite-android and Nutiteq to render Archaeological datasets. One of our sample data sets has 7000 polygons that turn into 400,000 objects in our renderer.
Is there a common GIS ...
6
votes
2answers
112 views
Algorithms for optimally locating points
I am trying to compare locations of where several thousand facilities have been actually built to where they would be optimally located to minimize travel times of the population (represented by ...
11
votes
2answers
348 views
How to equalise colour, brightness and contrast across several scanned paper maps
I am a vectors guy mostly, but for a current project I need to work with a bunch of old scanned paper maps (ww2 bomb damage maps for London, if your interested!)
We scanned and georeferenced the ...
15
votes
5answers
2k views
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 ...
5
votes
3answers
1k views
Slow IE8 responsiveness with OpenLayers and many features
Background
Adding about 700 sites to an OpenLayers Map. Firefox 11 and Google Chrome display the sites just fine. IE8, which is the organization's standard and will not be upgraded for the ...
1
vote
0answers
20 views
How to make some constraint to be evaluated first in mysql?
SELECT BusinessID
FROM
tableauxiliary
WHERE
MBRContains(
GeomFromText (
'MULTIPOINT(-6.1928749092968 106.7651250907,-6.1771250907032 106.7808749093)'
),
...
10
votes
1answer
228 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 ...
8
votes
0answers
54 views
Alternative indexing methods for point set operations
It is common to use a bounding box spatial index to improve performance when working with a large number of features. Where operations are performed against individual geometries with a large number ...
2
votes
3answers
159 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 ...
2
votes
1answer
303 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 ...
6
votes
1answer
332 views
PostGIS query vs QGIS filter
I have a PostGIS dataset with around 3 million shapes. I only need to view about 1,500 of these shapes at any given time, but the shapes I need to see depends on which feature is selected in a ...
7
votes
3answers
1k 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 ...
0
votes
1answer
600 views
CQL Filter in Geoserver very slow?
I am experimenting with CQL filtering in Geoserver. I have two layers, one (A) has 8000 features, the other one (B) has 3000 features or so.
I would like to search of layer A for intersection with ...
3
votes
0answers
122 views
how to increase request feature speed?
I use Geoserver with Oracle DB.
Amount of records in DB is less than 4000, but feature request takes 5-6 seconds. How can I speed up this?
P.S. Native JAI is false in my Geoserver
UPDATE:
I have ...
8
votes
2answers
379 views
How to speed up space partitioning in postgis?
I've a bunch of overlapping polygons and I'm trying to partition the space to avoid having overlapping ones. I think my problem is fairly simple.
Using some ESRI product and ...
13
votes
2answers
3k 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 ...
4
votes
2answers
200 views
Fastest way to remove matched points
Hoping someone can see a faster way of doing this, because at the moment I'm averaging 9 hours per run for what I'm trying to do and well basically getting my behind chewed off by the boss :-)
The ...
5
votes
1answer
446 views
Speed up pgRouting point_to_id using new <-> operator in PostGIS 2.0.0
The point_to_id function, which assigns a node id to a point based on existing nodes and tolerance, is using a query as follows:
SELECT
id, the_geom
FROM vertices_tmp WHERE
...
5
votes
1answer
442 views
How to Optimize Openstreetmap Tile Rendering?
I am currently trying to render Water (3,198,333 records) and detailed world borders (processed_p) for the world. I am successful in rendering both layers, but I am not happy with performance.
My ...
3
votes
1answer
150 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 ...
5
votes
2answers
1k views
Geoserver WMS tile rendering is too slow
I have following geoserver status. I have installed JAI but memory used by jai is 0 and image rendering for wms is very slow.
Is it issue with memory allocation? I am using Sql server 2008.
1
vote
1answer
332 views
Enhance performance of a join query for mapnik using postgis
I use mapnik to render map with datasources from a postgis database. One query is a join on two table, one with a geometry (a polygon) and the other one with some fields I want to use for rendering. ...
3
votes
3answers
2k 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 ( ...
5
votes
1answer
270 views
What is the best way to prepare digital orthophotos for the web?
My system: Linux Ubuntu 10.04 server (100gb: 4gb RAM: 32bit) /tomcat6/geoserver/geowebcache/FWTools
My Objective: Create Aerial Photo coverage in ETRS89 N32
My Data: 1300 3 band Orthophotos in Tif ...
4
votes
3answers
341 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 ...
2
votes
2answers
909 views
How to optimize a WMS request by limiting number of tiles?
I want to display the layer using WMS and meanwhile I want to limit the number of tiles with their respecive BBox when map is loaded. At the backend I am using geoserver.
I can limit the number of ...
13
votes
7answers
1k views
Fastest way to spatially join a point CSV with a polygon Shapefile
I have a 1 billion point CSV file and a shapefile with around 5,000 polygons. What would be the fastest way to spatially join points and polygons? For each point, I need to get the containing polygon ...
6
votes
1answer
743 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 ...
3
votes
1answer
363 views
Shorter Version of this SpatiaLite Query
I've been doing some spatial queries using spatialite, and they're large enough that a spatial index becomes a must. An example of using an index is given in the tutorial
spatialite> SELECT ...
6
votes
1answer
155 views
Optimize GEOSGeometry's spatial operations by avoiding thread-safety checks
A ranking algorithm I'm developing for a Django webapp requires performing spatial operations (within, intersections, sym_difference, etc.) using a query against large number of geometry objects.
...
10
votes
3answers
889 views
optimize nearest neighbor query on 70 million extremely high density spatial point cloud on SQL Server 2008
I have about 75 million records in a SQL Server 2008 R2 Express database. Each is a lat long corresponding to some value. The table has geography column. I am trying to find one nearest neighbor for a ...
8
votes
4answers
674 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 ...
31
votes
3answers
4k views
Are there newer routing algorithms (than Dijkstra, A*) in GIS databases?
There are works like Reach for A* from Microsoft researchers and Highway Hierarchies by Sanders and Schtolz (if I spell the name correctly) from Karlsruhe Uni. Both of them reduce the calculations ...
3
votes
2answers
558 views
Generate cache tiles for EPSG:27700 for use with OpenSpace
I am using GeoServer 2.1.0 (windows jetty local install for dev), open layers and Ordnance Survey openspace api and have a set of shape data that I am using as an overlay.
Everything is working as ...
4
votes
2answers
684 views
Qgis is slow with complex 'postgis query' layer. How to speed up?
I have a postgis layer in Qgis that is a result of a complex query. Every screen update, Qgis runs the Query again and that's slow.
Any suggestion on how to speed up?
EDIT - Here is the query:
...
5
votes
3answers
2k 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 ...
7
votes
3answers
722 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 ...
11
votes
4answers
1k views
Speeding up OpenStreetMap PostGIS querying
I have OpenStreetMap data for the Netherlands loaded into a PostGIS database (PostgreSQL 8.3 / PostGIS 1.3.3) using the osmosis schema. This means all tags are stored in a hstore field. In addition to ...
19
votes
5answers
5k 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 ...
7
votes
3answers
2k views
Poor Performance when using Spatial Indexes in MySQL
Re-post of a question asked on Stack Overflow when it was suggested this would be a better forum.
I'm trying a little experiment at pushing a data set which is not geo-spatial but fits it quite well ...
2
votes
2answers
1k views
Postgres/PostGIS Spatial Query Performance Problem
I have a query in Postgres/PostGIS that I am a bit confused about. The spatial intersection happens very fast, ~ 2 seconds for 10,000, but the update takes > 15 seconds for the same number of points.
...
8
votes
4answers
1k views
Best way to find the polygons crossed by a line
I'm trying to find all the polygons crossed by a single line (a GPS track).
I'm using the OGR library (from python) for computing this, but it's currently a bit 'brute-force' (and slow). For every ...
6
votes
5answers
854 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 ...
6
votes
1answer
529 views
Is there anyway to make GPModels with python scripts execute faster?
I do not know if anyone else has this problem but my GPModels that include simple python scripts seem to take way too long to execute. One example is a model I built which is a simple select feature ...
