A view on Ghent
First of all, ceci n'est pas une carte. This is not a map. Observant viewers will notice it is lacking a scale, a legend, an indication of the north.
It is merely an image. A bird's eye view of the beautiful city of Ghent. Unlike maps, it is not intended for navigation, education or transferring information. Its sole purpuse is admiration.
So what are we looking at then? You're (mostly) looking at the 1 meter resolution digital surface model (DMHVII), made available by Agentschap Informatie Vlaanderen based on airborne LiDAR measurements of the surface.
By using GDAL's sloping algorithm, I transformed the DSM pixels from absolute height values in meters to sloping angles between 0 and 90 degrees (based on adjacent pixels). By coloring the image from light (0 degree slope, a.k.a. flat) to dark (90 degree slope), you get a stunning view from the sky.
Then I added the water bodies. Because water surfaces reflect the LiDAR beams in various directions, water surfaces are not very beautiful in the resulting DSM. So I cut out the water from the OpenStreetMap dataset and overlayed it onto the image.
Gravensteen on the left, Museum voor Schone Kunsten on the right.
To have it absolutely perfect I had to perform one last task: because the water in OSM covers the whole area, I had to cut out the bridges (since they obviously should be over the water). I used the bridge surfaces from the GRB dataset (again from Agentschap Informatie Vlaanderen) for this task, because they contain the actual bridge surface instead of a line, where I would have to guess the width, which wouldn't have been nearly so perfect.
Sint-Pieters church and abbey on the left, Leopoldskazerne on the right.
The result is a bird's eye view on Ghent with a level of detail you've probably never seen before. Since we now know what we're looking at we can cleary see the differences between the different kinds of roofs: buildings with a flat roof are white with a dark border, saddle roofs also have a dark border but are grey (45° angle) with a white line separating both sides of the roof (rooftop line is flat). Can you spot the dome roof of the Wintercircus or the characterisic roof of the Van Eyck swimming pool?
The level of detail is amazing: you can cleary identify churches, museums, railroads and parks. You can identify individual trees marking the Coupure. Did you spot the hill that can be found in the Arbed park?
You can see the trains parked at the Dampoort bundle and the signs above the motorway indicating you should take the exit to visit Ghent. Any idea what the parallel dotted lines might be going north-east near Dok Noord?
I'll leave you exploring and admiring some more ;)
— Roel