Webrings - Maps - Trolleys and More
Wednesday, November 20, 2013
Some Grass 6.4.1 Visibility Experiments using the Kolumna Zygmunta at Castle Square Warsaw
Please ignore the scale bar, it is incorrect and I cannot remove it.
In this experiment, the using the raster visibility option, the height of the column was raised to 541 meters, which is the height of the World Trade Center. Not taking into consideration the curvature of the earth, the column would be observable throughout Poland except in the white areas. I do not know the reason for this. In the south, it would be visible at selected high elevations. The range is set to 90,000 meters.
In this map above, I brought in a shape file (vector) of important roads in Warsaw. The red square is the location of the column. The yellow coloring shows where in Warsaw a 1776 foot Kolumna Zygmunta would be visible. It would be visible of course, throughout Warsaw, but I cannot give a reason for the few white gaps in the map. These white gaps do not correspond to high elevations.
In the map above, I set the Kolumna Zymunta height to 22 meters, its actual height. If no buildings were blocking the view, or if you were looking down a wide boulevard, there would be gaps in Warsaw were the monument would not be visible. The red areas are higher elevations outside of Central Warsaw. Range is 30,000 meters.
In the map below, I used the option in GRASS to correct for the curvature of the earth for the visibility scenario at the Kolumna Zygmunta with the incredible height of 1776 feet.
The central Warsaw area is indicated by the rectangle.
In the map below, I used an option to create a map based on elevations that are based on a density function:
The Central area of Warsaw is indicated in red.