Implementing Point-based Costs in pgRouting pgRouting is a great tool but it does have certain limitations. One limitation is that one cannot have costs at specific nodes. All costs have to be edge based. Discussion on Node/Edge Costs in pgModeler For example, suppose a network has a stop valve between two pipes. Normally the stopRead More
BIT (Before Internet Time) it was probably true that we had a very small circle of friends or acquaintances. These people, whether family, friends and colleagues, were people we had actually (physically) met. As part of meeting people, one comes to some sort of estimation as to quality of their friendship, their character and reliability.Read More
There has been some discussion over on the PostGIS email list about the use of primary keys on tables by GIS client software such as uDig, QGis, MapInfo etc. It is a discussion that comes up now and again (perennial, I suppose) especially when new users of PostGIS (or Oracle on the Oracle forum etc)Read More
In my consulting travels I, like many other database-loving specialists, find databases with little (a Primary Key, perhaps) or no constraints being applied to the data model managed by a relational database (which may be Oracle, SQL Server, PostgreSQL, MySQL etc). I finalised a report for a Government Department here in Australia recently where thisRead More
Over at Alex Willmer’s Misspelled nemesis club there has been a (now-closed) discussion on the successor to the ubiquitous shapefile. Alex points out a lot of the benefits of the shapefile (and there certainly have been many). Before we discuss its “successor”, we should reflect on our business needs and the problems we had withRead More
I came across the Maps Of War website today – isn’t it amazing that you can Google all you like but completely missing interesting websites. On the site is a cool shock wave flash (SWF) “movie” showing the various empires that have conquered part or all of the middle east since recorded history. It isRead More
Yesterday, Tuesday 20th January 2009, I gave a flawed, imperfect, rather long talk called Free And Open GeoData – From Shadows to Reality at the March South Together, linux.conf.au 2009 Conference at the University of Tasmania. If one wants to get a message across, and perhaps be entertaining, one has to sprinkle one’s talk withRead More
On Tuesday November 11th 2008 I gave a 1 hour presentation on spatial databases entitled An Introduction to Spatial Databases to the Boader and District Spatial Information Group (BADSIG) at Albury NSW. The presentation was rather long as, generally, GIS practitioners are usually unfamiliar with database technology (no fault of their own) and so IRead More
I gave two presentations at the Australian Oracle Spatial Forum held at the Novotel Hotel, Sydney Olympic Park on Thursday 28th August 2008. My two papers were: Automated Layer Management – Experiences At Mid Coast Water Gridding vs Simplification in Extracting Performance from High Density Data The first was co-authored with Mr Brendan Soustal thoughRead More
There is a useful exchange going on over on the Microsoft Forums in relation to the paucity of information on geographic objects (as against planar objects) in the OGC SQL standard: this is in the context of SQL Server 2008 “Katmai” Spatial implementation. This exchange occured over Microsoft’s reading of the OGC standards in respectRead More