At least that is the theory Martijn tries to work with.

The age in days for OpenStreetMap nodes

You can see a clear pattern emerging here, apparently there are areas which get mapped in a short period of time and never touched again. The white squares just didn’t have any nodes in it, so they contain no data.

The version of OSM nodes

It is more difficult to see patterns here. Whereas with age in days the number gives you an instant grasp of the meaning, the version number is less obvious. We probably need to do a statistical analysis of version numbers in OSM. This way we can attach some (relative) meaning to the average version number.

The red circle is the final location of the node and the path is the order of changes. You can see that the first changes were much more rough than the last ones.

I also did the same for an entire way, where the way itself is shown in blue and the versions of the nodes are shown next to the nodes.

The trouble is that it is currently quite difficult to get the full (spatial) history of an area in OpenStreetMap. Once we find a way to do so I hope to generate more and play a bit with different visualization styles and methods.

To visualize these tracks I used Processing, ‘an open source programming language and environment for people who want to program images, animation, and interactions.’  There are lots of plugins to read different data formats, an interesting one for this project is the gpx library. The plan was to render the tracks of each person in a different color, tracks which happened at the same time should be drawn at the same time. This way you can see which people are at the same time at the same location. Each track would fade out in time, leaving a thin line for past tracks.

To do this on a track-basis however turned out to be quite difficult for my limited knowledge of Processing and the time I had available. So instead of using the gpx module I created a flat table with all locations sorted by time. Each row of the table contains lon,lat,color-id,time. The program iterates through all 42000+ rows and draws the locations as a dot. The size of the dot depends on how ‘old’ the point is. The last 200 points are drawn with a diminishing size, creating the worm-like effect in the animation. Note that it doesn’t take into account the actual time between points, just if it is next in line.

A few tweaks were added: Holland in unprojected lat-lon looks odd to dutch people, so I implemented a simple projection library to reproject the points to a semi-RD (dutch projection). Also I wanted to dynamically zoom to the action (not everything was happening in Amsterdam). I did this by calculating the minimum and maximum X and Y for the last 200 points. I wanted the location of our office building to be in view all the time, to provide a point of reference.

The source code can be found here if you are really interested. There are three files: Table.pde as written by Ben Fry for his book Visualizing Data, Soprojection.pde, written by Steven Fruijtier at my request and Drawing.pde is hacked together by me. This is a very crude and brute-force approach to render a series of tracks, so please use it with care. Since it needs to recalculate each point for each frame it tends to become slower as it advances through the table.

Click here to view the embedded video.

BruTile @ the Surface

Once we got the basics running I tried to edit the XAML to make it look better. This turned out to be harder than expected. The surface has once again its own default designs, which in my opinion are worse than the WPF standard designs. The default look is grey and square. So I wanted to change it to something more akin to our other touchtable applications: white and round. However Paul used a ScatterView component to display the layerlist and the geodan logo. He had read that one can just drop components in a ScatterView, without the need to embed them in ScatterViewItems. This is true, but it is a nightmare for the (non-initiated) designer. What happens is that the grey-square design of the ScatterViewItem is drawn beneath any layout you come up with for your own item. This is a very puzzling behaviour, although not entirely unexpected once you know that the ScatterViewItem exists.

Once I solved this issue I could seriously try to change the layout of the ScatterViewItems. Here however real glitches appeared. We use rounded borders and dropshadows for our items. As you can see below there are (at least) two issues:

Rounded border on the Surface don't work

The dark rectangle in the top of the image is actually a shadow of  a ScatterViewItem which for some reason doesn’t start below it. However this makes it easy to see the first glitch in the rendering. As you can see there is a thin dark line near the edge, which makes a weird square corner at the corner. This shouldn’t be there and when you resize the ScatterViewItem down, the shadow becomes darker (as it should have been in the first place) and the line is not visible anymore. If you don’t use rounded corners on the shadow the line is still there, but harder to notice because it is exactly following the edge of the shadow.

The second annoying glitch I’ve found is the gap between the border and the content. If we zoom in a bit on the layercontrol you can see there is a pixel space between the border and the content:

A gap between border and content

So far I haven’t been able to eliminate the pixel wide gap. It doesn’t look bad in our application right now, but in general it is bad that there is such an uncontrollable gap. So I have the feeling that the Surface people are not a big fan of borders in general and rounded border specifically.