Timesliding canvas maplayer
After someone saw my BAG building data movie 
he asked if it would be possible to create an interactive map of the entire Netherlands. This made me think, since creating the movie was a very time consuming action. The problem is that there are about 6 million buildings in the BAG database. This makes the data a bit unwieldy to use directly in the browser. The old fashioned way to do time series on maps involves creating a new layer for each time-moment (year in this case). This would mean that there would be over 150 layers to be loaded on the map and switching between those for the ‘time sliding’ effect. Apart from the hideous task to set up 150 almost the same layers, it would end up with too much images for a browser to handle.
Dymaxion Map
I’ve been thinking a while about creating a nice SVG map in the Dymaxion projection to hang on my wall – being a GIS expert I need to have a map on my wall 
However Dymaxion is not like most projections and standard GIS software doesn’t support it. Luckily there are some tools available, most important the Perl module Geo::Dymaxion, written by Schuyler Erle. This module transforms lat/long coordinates to dymaxion coordinates relative to an image size. This means it is easy, given an existing dymaxion map to plot point s on top of them, as shown in his book mapping hacks, code here.
kõik – drawing menu
The first short movie in the kõik on the MS Surface series; the drawing menu:
TileSeeder
Design for a python based GUI program for tile management.
(Image taken from the presentation I’m giving at foss4g 2010)
Visualizing OpenStreetMap history – part 2
Thanks to the hard work of Vincent we now have a database with the average version and average age of nodes per grid cell. Now we can start to get a feeling of the data. I’ve rendered both datasets for Amsterdam on a 10x10m grid. In general the idea is that red is bad and green is good. The younger a node is, the more likely it reflects the current situation in the real world. Also the higher the version number, the more people have been looking at that node and corrected it.
At least that is the theory Martijn tries to work with.
The age in days for OpenStreetMap nodes
Visualizing OpenStreetMap history
I’m working with Martijn and Vincent on a way to visualize the history of OpenStreetmap data for their analysis of the ‘crowd-quality’ of the data. I used my favorite visualization tool Processing to visualize the history of one node:
Creating a timelapse movie with ubuntu
It has been a while since I made my last timelapse movie and I figured that today was a good day to check the status of linux and timelapsing. A quick google gave me gTimelapse which should allow my to use my dSLR as a timelapse camera. This would give me two advantages over my old set-up (and one disadvantage). My old set-up was a Nikon S4 with a power adapter and a reasonably big SD card. Having a power adapter meant that I could leave it running for months, which gave me for instance:
Visualizing gps tracks with Processing
At work we got an i-gotU (a GPS logger) as a Christmas present. To show what one can do with it I decided to ask a few people to use their i-gotU to record their travels for two weeks. This resulted in over 42000 locations done by 8 different persons. Each person got his/her own color in the visualization to be able to see when people were near one another. Since the office is in Amsterdam and most people live in (different parts of) Amsterdam you can quickly see the contours of Amsterdam’s city-plan appear. Also interestingly is to note that people have their own specific areas where they spend most of their time.
Perceived WCS inaccuracy
Working with WCS I discovered a small but noticable shift of data in all three major OSS WCS applications:
- Geoserver 2.0 (SNAPSHOT downloaded 8 december 10.19UTC)
- Mapserver 5.6.0 (MS4W Base installer v3.0 Beta 7 + MapServer 5.6.0 release Upgrade)
- Deegree 2.3rc1 (Apache Tomcat 5.5.28)
To find out what the problem exactly was I’ve done some testing. I’ve taken a GeoTiff and configured all three the WCS applications to serve it. Gdalinfo gives us the following information, basically it is a GeoTIFF in epsg:3035 with a native resolution of 100m/pixel.