If you are using QGIS to work with aviation data you may have noticed that by default there are no aviation fonts, no aeronautical charting symbology and there are no providers that I am aware of for this type of data. I have started out an online repository about 3 years ago in github called aeronautical_charting with the idea of filling this gap, there are some svg icons loaded and can be used free of charge as you wish.
Recently I have come across the fact that I can also share styles and with that in mind I am extending the repository to also include styles that you can apply to lines and polygons and not restrict it to only icons. The first style I want to share is the one for Prohibited, Restricted and Dangerous Area.
In QGIS there is a way in which you can modify the geometry for display without actually modifying the geometry itself (pretty neat right?) for this style what I did was get the polygon, apply a buffer to “erase” a portion of the inner area to just have a band around to which I applied the hatching technique.
This is the end result in QGIS.
To use the style you can just visit the github page and download either the complete zip file or just the individual style.
Once you have download it and save it to a location on your computer, let’s add it to QGIS.
Open QGIS and go to Settings > Style Manager
Style Manager is now open, we can click on the Import item option
Click on the browse option as we need to go fetch the file that has the styles we want to import
Search for where you have downloaded the style and click open
The following import window will be displayed, just click the item you want to import (in this case it is an individual style but that could change in the future) and eliminate the additional tag(s) unless you want to add your own. By default it has a tag aviation embedded. Once you are happy with how everything looks click Import
Now you can click the aviation tag in your Style Manager and see the new symbol added and available for use and we can close this window
To apply the style to a polygon just double click on the layer and go to the symbol selector, change the filter to aviation and click on the right symbology to use
The style has been created to work with EPSG:4326 (WGS84) but depending on the scale or if you are using a projected coordinate system there one additional thing you will need to do to be able to see correctly the style and it is to modify the buffer distance to a value appropriate for your scale in WGS84 or use meters that make sense in a projected coordinate system by doing the following
Double click the symbol so the Symbol Selector shows up, notice how the style is composed of a few Geometry Generators (remember we are not modifying the geometry just the display of it)
Now click on the Geometry Generator containing the hash and you will be able to see how the style was created in the first place, it is a buffer going inside to eliminate an area an using a difference function to just get the portion that we need (In simple terms a geospatial cookie cutter)
The distance shown there is in decimal degrees because I used WGS 84 (EPSG:4326) at a large scale if you are using a smaller scale or a projected coordinate systems in meters you will need to change this value. eg. -2000 for meters in UTM projection. The value is negative since we need to go towards the inside of the area.
Hope this works for you and enjoy the style, will be uploading more in 2021! In the future I will try to update this style to be based on a scale and if possible to detect if it is a projected or unprojected coordinate system