viewshed | Calculates the the viewshed given a location | Continuous Deployment library

---- Update with what I got so far and what's left to resolve can be found in point 3 below ----

Using Octave I want to create 30 horizontal box and whisker plots without spread (x-axis) from 30 different GeoTIFF's. This is a sketch of how I would like the plot to look like:

Ideally the best solution for me would be an Octave code (workflow) that would allow me to place multiple GeoTIFFs in one directory and then with one click create a box and whisker plot for all GeotIFFs at once - just like the sketch above.

A GeoTIFF-sample with 3 GeoTIFF's can be downloaded here. The file looks like this in QGIS:

It holds elevation values on band 1 (the ones that each box and whisker plot should be based on, and no data values (-999), the no-data values should be excluded from the plot.

Right now this is what I got:

1. Using img = imread ("filname.tif") gets the file into Octave. Using hist (img(:), 200); shows that all cells are concentrated around 65300. imagesc (img, [65100 65600]) follwed by colorbar displays the image extent but's it's clear that this way simply doesn't import the real cell values. I can't find a working solution to import GeoTIFF's with cell values, therefor my current work-around is exporting the GeoTIFF from QGIS with gdal_translate -of aaigrid which creates a .asc-file that I manually edit to remove header rows, rename to .csv and load into Octave. That .csv can be found here.

2. To load it and create a box plot I'm currently using this code (thanks to @Andy and @Cris Luengo):

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