At critical mass events bicylists meet and drive through a city as a convoy. This creates awareness for cycling as a mode of transport. The following animated map shows the Critical Mass tour through Essen in december.
Based on the previous animation for november, I identified some patterns of how such a convoy might typically move. Some of the identified behavioral pattern are again visible in this december tour. A preference for wide main roads can again be seen. Though with the background map showing only building polygons this is not as well visible. Even though there is no prefixed tour, the convoy seems to move in a partially destination-oriented way. The tour to the north-east circled around the Zeche Zollverein site and back. The small loop in the south served to retrieve a bicyle grill from a participant’s garage. The tour ended at a location in the south for an end-of-year get-together. The supposed preference for right hand turns resulting in clockwise loops cannot be observed in the december tour. The two visible loops are both counter-clockwise. Though the legal basis for these events is fairly clear, the tour was held up by ill-informed police officers. The tour continued after some lengthy explantions.
The map also reveals some of the hidden beauties of Essen. The Zeche Zollverein in the north-east is a historic coal mine. It is Essen’s trademark and an Unesco World Heritage site. Large free spaces are visible between the building polygons. Due to the many parks and forests in the city, Essen was the European Green Capital 2017.
The animation was constructed using the open source tools QGIS with the Time Manager plugin, Gimp and the GPSLogger app. The background shows building polygons from Open Streetmap data.
The general wokflow was as follows. I logged the tour at a 5 second interval using the GPSLogger app. I wrote a python script that converted the individual points logged in a CSV file to lines in a geojson file with time as an attribute. This geojson file I opened in QGIS and converted it to a shapefile for use with the Time Manager. I set up the Time Manager with a time interval of 51 seconds. This leads to a nice counting up of seconds in the time display. I added a manually constructed point layer with the labels and associated times when the tour passes those points. The resulting time animation I exported as individual frames in PNG format. These files I loaded as layers in gimp. I applied the gif optimization filter and adjusted the color palette to 255 colors in order to get a clean white background. Finally I exported the animation as a gif.