Open Street Map into QGIS.

From Open Street Map. CC BY SA 2.0 license.

Getting and using Open Street Maps in QGIS. 

Some of you have asked if there was possible to get maps into QGIS. Besides inputing files from other maps services, the Open Street Maps database is a good source for maps, even if sometimes they may be incomplete. Open Street Maps is a collaborative project to create a free editable map of the world, with a database available through the Creative Commons Attribution-ShareAlike 2.0 license . It is under development, so not all areas are covered with the same amount of detail, but many parts of Europe are quite reliable, and you can even get data from other areas in the world. The best thing is that it is free and that all material is provided with a very liberal license (CC BY-SA 2.0). You can also download images of maps, etc (Google Maps seem to have a much more restrictive license, check point 10.1.3).

There are two ways we have found to get the data into QGIS:

A. The easy one, but limited data:

1-Download shape files of Open Street Maps from cloud mate ( http://downloads.cloudmade.com/europe/northern_europe/sweden#downloads_breadcrumbs). You can download many parts of Sweden (Stockholm among others), the whole Sweden, and many other parts of the world (http://downloads.cloudmade.com) so this may be useful for future projects. Remember to download the files that are called shapefiles, like this one for Stockholm http://downloads.cloudmade.com/europe/northern_europe/sweden/stockholm/stockholm.shapefiles.zip 

2- Unzip them, and you can open them in QGIS (either by clicking the files with ".shp" extension or directly from QGIS, with "Layer > New > New Shapefile Layer" in the menu bar, for example). They will come up distorted, because of the coordinate system of the file. If you wonder what the coordinate system is, and how important is the history of representation, check this http://en.wikipedia.org/wiki/Map_projection).

3- You can change the coordinate system to any other you want, for example "Google Mercator", which is the same that Google Maps uses. You can do this by going to "Settings > Project Properties" and selecting the "Coordinate Reference System (CRS)" tab. There "Google Mercator" is under "Projected Coordinate Systems > Mercator > Google Mercator". Check also the box that says "Enable 'on the fly' CRS transformation", and press OK.

That was that.

You can go now and "Open Attribute Table" on the layer (by right clicking on it) and select data according to the table. As you can see the amount of data is limited, though substantial (if you include all the shapefiles), and it will allow you to match any data with the map of Stockholm.

B The proper way, though complicated.

For having access to all Open Street MAp information you will need to install a database in your computer, that you will access through QGIS. This involves installing some software and using the command line. I had a bit of trouble doing this, but I finally managed. Here is a tutorial for MAC:

We had problems installing PostGIS (if you try to create a database as explained in the tutorial  and "template_postgis" does not show as an option in "Template" , you have the same problem). To fix the problem, You can try to find where the installation zip for PostGIS is in your computer, or download it from here:

and run it. Then follow the steps as indicated in the rest of the tutorial (download osm2pgsql … etc). You also have to enable to save your password when you start the server in pgAd­min III.

You can fins another tutorial with even more advanced style editing explanations here.

Heights Applet update.

We have updated the heights applet for those of you that may want to use it in the project (or in the future). The new applet works exactly as it did before, with a couple of added features:

1.  Smoothing:

Now the applet has a smoothing spinner, set by default to 0 (no smoothing, as before). If you move the slider to a number larger than 0, you will see how the heights even out (with a very large number the surface will  become basically flat). The Smoothing is a bit similar to that used in the google ngram viewer   that we have shown as an example in the course.  As you may see in that example, the smoothing gets rid of "noise" (big differences in the samples) at the expense of detail. The more you smooth, the easier it is to see general trends, but the more difficult it is to see specific events. The smoothing, both in the Ngram Viewer and in our applet works by averaging the value of each sample point with those around it. One can select how many samples around are going to be used in the averaging (this is the number that appears in the smoothing spinner box). 

For the smoothing (http://en.wikipedia.org/wiki/Smoothing) the applet uses a formula for adding up and averaging the values of adjacent squares which is called a "Gaussian Convolution Filter"  . This is basically the same Gaussian Filter that you may have used in Photoshop, to reduce noise in images. What the smoothing spinner does is to specify the amount of neighbor  to each square cell that are going to be used to average values: 2, for example, means that it will average all the squares around each cell that are within 2 squares to the right and left and 2 squares up and down (2 square distance in x and y), using the gaussian formula.

If you do horizontal sections now (height curves or isolines, as they are also called) you will get much nicer looking curves also.

2. Frame:

By default the applet calculates the bounding box for the data (the smallest rectangle in which the data fits), and then it scales the grid accordingly. If one uses different sample data it may be difficult to compare them, since they will produce grids that are placed and scaled differently, even if they overlap . To solve this it is possible  now to have a layer called "FRAME" (or "frame", capitals don't matter ) that the program will use for making the bounding box. It will ignore otherwise the data in that layer (it won't count any polygon in the layer when calculating areas, for example), so don't put any data that you want to use on that layer! (see the examples included).

Here is the applet:

HeightsApplet03

We have put some sample data with the "frame" layer on also:

Sample Data (HeightsApplet 03, framed)

The applets are also under the Applets column on the right.

Spacematrix, Meta Berhauser Pont.

Spacematrix, Meta Berghauser Pont and Per Haupt.

I hope everyone enjoyed Meta Berghauser's lecture as much as we did!

Meta has kindly given us a copy of her presentation so you can have another look at it, here. We have also ordered the Spacematrix book at the library.  And here are also a couple of links to her work, that she showed during the lecture (we have added the links also to the software list on the right):

Spacemate

Gisdro
The co-researchers of the Rotterdam project that is presented by Meta Berghauser Pont should be mentioned in the presentation. The co-researchers are Akkelies van Nes (assistant professor, TU Delft) and Bardia Mashhoodi (PhD candidate, TU Delft). Furthermore, Per Haupt should be mentioned as the co-author and co-researcher of Spacematrix.