OSM coverage of Berlin over time

I was asked to design a cover for the thesis of our intern working on crowd quality in OSM. This image is a modification of the nice animations GeoFabrik produce on demand, in this case Berlin. Since it needs to be printed I couldn’t use the animation itself. Time moves within the image from left to right. You see that early in OSM-history there was just one highway and over time the data becomes more complete and hopefully more accurate.

Click here to view the embedded video.

The Surface has been hanging around in our office for a while and we’ve done lots of interesting small and big projects for it. However they’ve been pretty fragmented and to show what we could do with the Surface you had to use several applications which had many similarities, which was confusing. So we decided that it was time to create an application which would show all our new ideas and developments. Looking for a nice name we came across ‘kõik‘ which both means everyone and every(thing), which is pretty much sums up what we want to achieve: an application which can be used by everyone and shows everything we do.

It was originally designed for landuse planning. Planners need to be able to move and zoom a map, but also annotate on it. The trouble with touch devices is that there is no difference between drawing and dragging, unlike keyboard/mouse (drawing is left mousebutton and dragging middle for instance). Having to press a button somewhere on the Surface to enable/disable drawing was too confusing, people tend to forget that they pressed them and in what modus they are now.

Having a physical object on the table turned out to be much easier to use and remember. If there was ‘the’ object on the table, you could draw and if you want to move the map, you just lift the object and move the map. Having established the object as the drawing-toggle, I then moved all drawing related interaction to a menu activated and related to the object. Currently you can choose the color and line thickness and whether you want to draw a line or polygon or you want to edit existing features, undo/redo actions and add new drawing layers.

(Image taken from the presentation I’m giving at foss4g 2010)

I’m involved in EduGIS and one of the nice things about this project is that we have hundreds of map layers. However that begins to pose a problem for us; to produce a decent speed for classes full of schoolkids using it at the same time we are using tiling.

We currently use TileCache; a very nice and quick open source tilecaching program. However we keep adding layers and we need those to be quick when students are using them, but we don’t have the capacity to prerender (seed) everything, nor to do this on the fly. Since we mostly have dutch data, served at dutch students, we figured that we only need to seed a certain set of tiles; the entire country for the higher levels and the rural areas a bit deeper and the urban areas even deeper.

So I came up with the idea to create a desktop application to make it easier to create a complex seed that does more zoomlevels for certain areas and less for others.

Thanks to generous development time invested by Christian there is a first alpha available around foss4g at googlecode

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.

Click here to view the embedded video.

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.

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.

Basic animation of hiding a card from view

After watching the Secondlight demo from Microsoft, Johan came up with an idea to show ‘private’ information on a touchtable. For instance during a board game on the table a player wants to view his private stack of cards. In a traditional game he would have his cards turned upside down and would view them behind his hand. This behaviour can be mimiced on the table as well. If the user puts the side of his hand on the table the table can show the card within the confines of his hand.

Click here to view the embedded video.

The movie, voiced over by Geodans own Barry White