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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41 views

How to find the best location to put a facility within network so that all points are near a facility?

Suppose I have many points distributed in a network. I want to place three facilities in the best way so that all points are near a facility. How can I do it? Any solution and software should be fine ...
2
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2answers
67 views

Maximizing Code Performance for Shapely

I've written this code in order to calculate the percent cover of grassland within a national park, within 20km^2 of points of recorded occurrences for a species. It is designed to only consider the ...
3
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0answers
51 views

Postgis database query optimisation

I have a set of rasters in DTED format which I load into postgis database using raster2pgsql command line tool. Each of rasters is simply stored in a row and described by rid and a value of raster ...
3
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3answers
254 views

How does Jenks optimisation method assist in ESRI mapping?

Why would someone use the Jenks optimisation method in ESRI mapping? What would be easily located or discovered with this analysis?
3
votes
1answer
269 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 ...
6
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4answers
737 views

How to optimise and speed up Python code? [closed]

Again my lines of surface runoff... I made a script, solving the issue when lines cross other lines. Something like generalization. Like on the picture below. The problem is that I have to solve 30 ...
2
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1answer
80 views

Maximize clusters of points from coordinate data

So I am definitely new to the GIS world, so bear with me if I don't know the best way to articulate my problem. That said, I am ready to learn, I would definitely welcome any direction that you all ...
0
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1answer
42 views

Improving speed on pgRouting on table update with many rows: faster to loop on each row than a table update call?

I am updating thousands of rows in a survey table finding shortest path from each place a survey respondent visits. My code below is the query I use to update the blank route column. The function ...
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0answers
20 views

How to build an optimization model? [duplicate]

I want to make a model using QGIS. Is it possible? Then how can I develop a model. can anyone help me?
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6answers
7k 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 ...
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5answers
2k 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 ...
8
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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 ...
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0answers
280 views

Shortest distance from pgrouting with cost not being length: optimal solution

I'm using pgrouting shortest_path_astar with a complicated cost function. It gives back the edges, vertices and costs. I would like to get the total distance of this shortest path (i.e., the sum of ...
0
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0answers
82 views

I could use some help with a bit of code optimization

See edit below. I posted here a couple weeks ago looking for some advice on the best way to iterate through data. You can find that post here. I have since done some tweaking to the code, and ...
0
votes
2answers
52 views

How can I optimize this point-linking query?

I have the following query, and am wondering how it could be optimised to run faster: WITH gps_nodes_1 AS ( SELECT "NODE_ID", "geog" FROM gps_nodes WHERE ST_Distance("geog",ST_GeogFromText('POINT( ...
1
vote
1answer
89 views

Wind turbine placement optimization and loss on surrounding house value

I am doing a geostatistical placement optimization study on where would be the optimal placement of a wind turbine in a Danish region. One of the variables taken into account is the cost on the value ...
14
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1answer
165 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 ...
5
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1answer
141 views

Optimize the locations of 2 additional restrooms on a trail (ArcGIS 10.2)

In the image below, the line is a trail and the point is an existing restroom. I would like to find the rough locations of 2 additional restrooms that minimize the maximum distance along trail from ...
5
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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 ( ...
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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 ...
3
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0answers
90 views

District heating expansion design with ArcGIS [closed]

I am quite new at GIS but I have some experience of the basic concepts involved in a workflow of them. What I currently want to do is to calculate the cost of expanding an existing district heating ...
2
votes
2answers
526 views

How to draw one rectangle in ArcObjects?

Is there button in ArcObjects "draw rectangle" such as in openlayers? Update Well, I use this code for drawing: ESRI.ArcGIS.Display.IScreenDisplay screenDisplay = Map1.ActiveView.ScreenDisplay; ...
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 ...
4
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1answer
148 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
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1answer
340 views

meeting point minimizing travel distance for participants?

The problem is to find the point minimizing the travel distance for around 100 persons in different regions who want to meet in the same place. Travel is by car not by plane. Assuming that I get ...
2
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1answer
367 views

Find nearest neighbours faster in PostGIS

I currently have a query that calculates the number of useful amenities within a certain radius of each town, using OSM data: create table places as select town.name, place, town.way, ( select ...
3
votes
2answers
484 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) ...
4
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3answers
477 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
0answers
130 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 ...
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3answers
3k 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 ...
36
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3answers
7k 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 ...
5
votes
1answer
532 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 ...
4
votes
2answers
392 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 ...
2
votes
1answer
594 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 ...
8
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2answers
192 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 ...
6
votes
1answer
2k 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 ...
8
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2answers
579 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 ...
12
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2answers
1k 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 ...
2
votes
3answers
223 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 ...
5
votes
3answers
3k 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 ...
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0answers
24 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)' ), ...
11
votes
1answer
365 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 ...
5
votes
2answers
3k 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.
3
votes
0answers
136 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
4answers
2k 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 ...
2
votes
2answers
1k 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 ...
7
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1answer
208 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. ...
6
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1answer
570 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 ...
20
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2answers
6k 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
1answer
261 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 ...