wkt syntax (howto)

Geometry types and their text representations

Geometry type	WKT representation	Comment
point	POINT EMPTY	empty point
point	POINT ( 10.05 10.28 )	point
point	POINT Z( 10.05 10.28 2.51 )	point with Z coordinate
point	POINT M( 10.05 10.28 4.72 )	point with M coordinate
point	POINT ZM( 10.05 10.28 2.51 4.72 )	point with Z coordinate and M coordinate
linestring	LINESTRING EMPTY	empty linestring
polygon	POLYGON (( 10 10, 10 20,20 20, 20 15, 10 10))	polygon
multipoint	MULTIPOINT Z(10 10 2, 20 20 3)	multipoint with Z coordinates
multilinestring	MULTILINESTRING M(( 310 30 1, 40 30 20, 50 20 10 )( 10 10 0, 20 20 1))	multilinestring with M coordinates
multipolygon	MULTIPOLYGON ZM((( 1 1 1 1, 1 2 3 4, 2 2 5 6, 2 1 7 8, 1 1 1 1 )))	multipolygon with Z coordinates and M coordinates

Advanced drawing in chameleon

Today i noticed the guys at http://www.uwaterloo.ca have been working on some really advanced javascript drawing techniques for chameleon. They used walter zorn's drawing library to create dynamic circle and polyline drawing tools.

opensource gis desktop clients

Recently some opensource (free) desktop GIS clients came to my attention.

• uDig (http://udig.refractions.net/confluence/display/UDIG/Home ) is a java-eclipse based environment for viewing maps (.shp,tiff,wms,wfs,postgis). The eclipse environment offers you ease of configuration to build your own gis-cleint.
• gvSig is a free multi langual gis-client in java by a spanish firm (wms, wfs). (http://www.gvsig.gva.es )

Basic clients

openEv is a basic gis-viewer by frank warmerdam (http://fwtools.maptools.org/ )

development environments

Lots of groups offer platfoms in which you can easily build your own desktop gis client.

http://www.geovistastudio.psu.edu

http://www.vividsolutions.com/jts/jtshome.htm

http://openmap.bbn.com

Free clients
- the guys at http://www.tatukgis.com created a Delphi.net environment in wich you can build your own viewer with a few clicks. But they also offer e simple viewer for free. Tatuk manages to put all gis-functionality in just a tiny 10mb application.

soon to come
- At http://fmaps.sourceforge.net they are coding to bring a decent gis-client to the linux-platform. They use postgis to store data.

sql-flavours

when talking to lots of databases you notice there are many flavours of sql. Once in a while it drives me crazy to get for example the syntax for a limit in db2 and so on. Recently i found a nice overview of the different flavours: http://troels.arvin.dk/db/rdbms/ So now we all know that a limit in db2 sql = 'FETCH FIRST n ROWS ONLY'

bbbike.de (open source navigation)

We recently discoverded an open source navigation tool (to calculate shortest distance between points of interest) at www.bbbike.de It can be used as a standalone perl desktop application or in combination with mapserver as a server based navigation tool on the web. Good work, as far as we know, the first open source navigation map.