The MacAlba

I’ve had a healthy relationship with maps since I was a teenager. Living in Scotland at the time, I used to purchase Ordnance Survey maps of the local area and pore over the paper – just looking at this and that. Then, in my early 20′s, I’d go hill walking and learn the names of the hills, find old and ancient ruins, monuments and stone circles, then use the maps to find my way home.

So how does this translate to the digital age?

I’ve been collecting tracks with my GPS receiver for some years now. Initially I didn’t know what I’d end up doing with the tracks though I did submit a set of Outback Australia tracks to the Tracks4Australia project. Tracks4Australia, being essentially a one-man operation, and having a slow turn-around, didn’t give me the outcome that I was interested in which was to see the result of my efforts appear on a map.

Some time passed and I became acquainted with the OpenStreetMap project. OpenStreetMap is a community-driven venture to create a set of geographic data from scratch that can then be used for any purpose without restriction.

The outcome is a global map. It will continue to evolve as further contributions are made to it. New streets, new housing developments, changes in land-use, and points-of-interest are examples of data that are being, and will continue to be, added.

A key restriction to what can be contributed is that new data may not itself be taken from copyrighted data or data which cannot be re-used for any other reason (eg it doesn’t permit derived works).

For my own part, over the past year or more, I have generated data that I have uploaded and annotated to create a map of the city of Armidale, bush-walking tracks in and around many National Parks in the area, and major and rural roads around the region.

The map of Armidale, for example, can be viewed at:

http://www.openstreetmap.org/?lat=-30.5146&lon=151.6711&zoom=14&layers=B000FTF

It may take a while to load initially; after it loads try zooming in to see street detail (click-and-drag the map too), then zoom out to see how Armidale relates geographically to the rest of the region.

To generate the data used to create the map of Armidale I drove, over a period of months, every street in the city. I initially just varied my way to and from work, and to and from the CDB. Then, at lunchtimes, towards the end of the mapping period, I would just go for drives around the remaining streets.

As an example of the type of use to which such maps can be put, if the local newspaper wanted to include a map of part of the local area to illustrate a story, they’d be free to generate it from OpenStreetMap and not incur licensing costs that may normally be associated with using third-party maps.

Another way in which this data can be used is to generate an image file that can be displayed on a Garmin GPSr. More on this later.

I previously wrote about my first attempt at a Google Earth (GE) “mashup” where I’d overlaid a Bureau of Meteorology rain radar image over a panel from Google Earth.

I’ve now modified the mashup to overlay two rain radar images side-by-side. I’ve taken the Grafton and Moree images and overlaid them over their respective ground areas. Writing the KML code was trivial; most of the time required to do this was in manually registering (aligning) the radar image over the ground area. while it’s not perfect, it’s adequate for my purposes.

To view and manipulate my mashup, download the KML file, save it to disk, then double-click it (or “open� it directly from GE).

Here’s what it should look like:

It might take a while to actually see some rain on this image – we don’t get all that much at this time of year.

I’ve only recently begun exploring Google Earth (GE). The Google Gods haven’t yet blessed the pane in which we live, it’s still in low-res, but the panes around us are in magnificent hi-res detail. I can even see a few graves in the neighbouring Hillgrove Cemetery now.

I’ve also been reading about people creating “mashupsâ€? – the combining of information, maps in this case, from more than one source.

My first attempt at creating a mashup involved mixing the Bureau of Meteorology‘s (BoM) rain radar image for this area with Google Earth’s view of New England and surrounding area. My mashup updates the radar image every 10 minutes. Unfortunately, it doesn’t rain around here that much at this time of year so it might take a while to view the results at their glorious best.

One benefit of overlaying the rain radar image on GE is that the viewer can take advantage of the 3D and pan, tilt, and zoom features to look at the rain from every conceivable angle

To view and manipulate my mashup, download the KML file, save it to disk, then double-click it (or “open� it directly from GE).

This is what you can expect, rain permitting: