Some details from the GPS-generated line drawings coming out of the work described in the previous post.
The length of the lines correspond to how much discrepancy there is in where the two GPS units I’m carrying think I am. The longer the line, the more they disagree.
In the above screenshot you can see how the big, crowded-together buildings of the Bull Ring (bottom left corner and running up the left-hand side) scatter the GPS signal around a lot, resulting in a completely different type of mark-making compared to the relatively open terrain of the ring road on the right hand side.
The dense cluster of lines about a third down from the top on the left-hand side is where my route takes me between the Fire Service Headquarters and the flyover of St Chad’s Queensway. Subways and railway lines cause interesting effects in other locations.