Strabo is a program that generates textured images and 3D models starting from
digital elevation maps (DEMs) in HGT format, as provided for free by the
U.S. Geological Survey.
The program takes in input a set of HGT files, and generates a TIF or VRML file as output. It has no graphical interface, and works using the command line interface. It is easy to compile with most ANSI C compilers, and was used with success with Linux, Windows and OSX.
The project was started in 2008 by Ester Cavalcanti (my wife) with my (Salvatore Sanfilippo) help in the coding side, while Ester was graduating in architecture at the University of Florence. During the years many students at the University of Florence used this tool in order to greate 3D models and textures of the Italian territory.
The code is released under the BSD license.
No update of the code is planned, but merging of pull requests will be performed. Forking the project in order to improve it is encouraged.
- 2D maps and textures generations.
- UTM projection with interpolation.
- 2D contour lines maps creation.
- Heatmap style contour graph.
- Coastline detection.
- 3D VRML output.
- HGT errors and noise fixing via interpolation.
- Cropping.
- Experimental labeling of specific points.
The following example generates images of the Sicily region of Italy.
To start you need to download the HGT files using the getsquare.sh shell script:
./getsquare.sh N36E014
In order to cover the whole Sicily, you need the following squares:
- N36E014.hgt
- N36E015.hgt
- N37E012.hgt
- N37E013.hgt
- N37E014.hgt
- N37E015.hgt
- N38E012.hgt
- N38E013.hgt
- N38E014.hgt
- N38E015.hgt
In order to generate a 2D image with texture and UTM project use the following command line:
./strabo n38e012.hgt-n36e015.hgt utm fix texture prescaling 4
The program will generate a file called output.tif that will look like the following image:
The following command line will generate an image showing contour lines:
./strabo n38e012.hgt-n36e015.hgt utm fix curves curvestep 250 prescaling 4
To generate a VRML 3D mesh, just use the vrml option.
The program generates the full list of options when called without arguments. Certain options and modes are obvious, others may need some more experimentation or reading the source code. Unfortunately we can't provide better documentation than that at the momoment, since we don't use the project anymore for years.