Sunday 14 February 2010

Driffield and renders

Today we went out to look at the town of Driffield. It's a market town which is advertised as the Capital to the Wolds, though I'd expect it to be in the Wolds to be the capital, not perched outside the edge. It went well enough, almost all of what we mapped was new.  There is a substantial chunk of the town which looks mapped at first sight, but I suspect will need going over again.  The roads look traced from NPE, they have tags like highway=unclassified when I think they are residential and they have no names. So, we'll check them out on the ground and get the real picture.

I have also added some streams from NPE.  I saw the stream flowing under the road bridge and the only real way to add it was from the old maps. Yahoo is very low-res and there's a cloud in the way.

Driffield will take many visits to complete, but it should be a pleasant place to wander around.

I have been experimenting with rendering my own maps lately.  I started to look at Java 6 (1.6?) over the winter and now it's turned into a project to render maps.  I have started with a tile-based drawing because it is easy to compare it with a Mapnik-rendered tile.  In due course I do want to render a map that is a single png file of a chosen resolution and of a chosen area. It's mainly an exercise to force me to get results from writing Java and, as yet, it is a command-line program.  I've looked at Swing a bit and it could form the GUI for selecting the area to map.

The latest, almost solved, problem is how to draw the coastline.  They are drawn as open-ended ways so the sea is not a closed polygon to simply draw filled.  I have resorted to creating a flood-fill routine (based on the work of others of course) to flood-fill the sea once the coast is drawn.  It may also be useful with drawing multipolygons too.

The next issue to address is how to manage the style sheet. I've looked at MapCSS.  It's interesting, flexible and extendable. It would make a degree of compatibility with Richard's work too. Parsing MapCSS looks to be a real problem to me. I could just create an XML format for the style sheet, but who in their right mind wants to hand-edit an XML style sheet to get a map to render? So I'm still thinking.  Any ideas would be welcome.

1 comment:

Richard Fairhurst said...

Very happy to help with the parser. I don't know Java but there are certainly similarities between it and ActionScript 3; and besides, I suspect the hardest thing is actually the data model for the parser, which is all working.