It took some time, but friday the GPS data logger arrived. It is a Columbus V-990, produced by http://cbgps.com. It comes with some software written in Java, so the most important parts are compatible with Linux, too. The first test failed, because I tried it in motion tracker mode, which does not seem to work very well at walking speeds. Got a track file with about 6 dara points for an afternoon’s worth of walking. Luckily I also had my phone’s GPS tracking in parallel, so I got some useful data from that. Yesterday I did another experiment, this time going to the Sants quarter’s alternative summer party near Barcelona Sants station. There I did not move very much between fetching beers, which helped with collecting variations in sampled position over a couple of hours. I am currently still evaluating that. The thing is, the device produces a CSV formatted log file with values filled up with null characters. This is extremely stupid, since this way it needs processing to be imported in spreadsheet programs as OpenOffice Calc or Gnumeric. If I quit the null characters, their own processing software for exporting to standard formats TimeAlbum can’t read the file anymore. So I am currently working on a small tool to filter out all the points with low accuracy (PDOP >= 2.0, perhaps) while keeping their silly format to use their GPX export afterwards.

Well, my first impression is that under urban conditions it does not make much sense to try and collect precision data with GPS, even in sparsely built areas.

Today I went around the block to collect the housenumbers for the building outlines I put into the map the last couple of weeks. I hope this will help with the reverse geocoding of street addresses. I also hope I worked out correctly how to do this. Basically I added the addr:housenumber tag to the buildings and then added the buildings to an Associated Street relation linked with the street. Now, things like postal code areas etc. are still missing, and I only managed 6 blocks in the neighbourhood, but its a start…

I did a walk today along Carrer de Marina from start to end, and added a few more details to the map where possible without recording too much (much to hot out there…). When I look at the Historial view, all I see in the area are my own editings and some more or less global changes from entirely elsewhere. Does that mean that I am the only one currently mapping in Barcelona? Strange… there still is a LOT of details missing…

I have been trying out a Samsung Galaxy Y Duos with Google Mytrack the last days. The accuracy of the recorded aGPS data changes somewhere between 3m and 20m radius of the actual position in mid-town area, which is pretty useless for finegrained recording, I would say. I guess open terrain data would not be much better in areas with large phone cells for the network assist. I just ordered a dedicated Visiontac VGPS-900 data logger for further track recordings, so next week I will do some track recording with both devices to compare accuracy.

I tried out the aGPS tracking with a Samsung Android phone yesterday in preparation for an excursion to the Montjuic cementary to record the labyrinthine street layout there, which would be most helpful to record how to get to specific monuments there. Unfortunately, the recorded track seem to have a large variety in the margin of error, probably depending on the correction available from the network at any given point in time. It look salright to record a few additional details in an area already heavily documented, but out in the field with a small number of large mobile cells it probably will be worse. I would not want to waste whole days meandering through the pathways only to discover afterwards that I got some sort of spaghetti artwork out of this… So… any recommendations on a sufficiently cheap but accurate GPS tracking device?

Sooo. The right building type for urban residential blocks with shops in the basement and the occasional business is building=apartments, if I understand that right. And to set the number of storeys, there is building:levels. Now: If I have a building with basement, intermediate plant, 6 storeys, attic and superattic, what do I put into levels? 6? 10? I think that might need some more detailed clarification…

Still working on details NE of Sagrada Familia, taking in a few bits and pieces every day walking the streets.

Added a few historic monuments around montjuic cemetary the other day. It would be most helpful to go there and track the streets within the cemetary with GPS, since it is very easy to get lost there and that is exactly where a detailed map would be useful… From the last visit, I’d estimate the overall effort at about three days, with some recording.