Tiles: Mapbox.com Aerial
Example #33 - Displaying an FAA chart in the BA3 Altus Mapping Engine
It is easy to download GeoTiffs and GeoPDFs from the web and display them on the sphere in Altus.
This example demonstrates how to do it with an FAA chart downloaded from the FAA's Web site.
This is the chart for the Dallas area. If you zoom in, the clarity is gorgeous, and the
registration is perfect with ground features.
Take these steps if you want to try it yourself:
- Go to the FAA site and download the geo-tiff of an FAA VFR sectional chart. Currently the URL for these charts is: http://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/vfr/
- The geoTiff comes in a zip file. Extract the .tif file from the zip file you have downloaded.
- Find yourself a Linux machine. If you are creating it yourself, the latest version of Ubuntu is easy to install, and will even run from a USB drive or a CD if you do not want to dedicate a machine to Linux. Any CentOS7 compatible flavor of Linux is fine.
- Install GDAL on your Linux machine if it is not already there (if the command gdalinfo will not run, then you don't have gdal). Type something like "install gdal ubuntu" into a search engine to get instructions.
- Install AltusRaster on your machine. AltusRaster will be used to convert the geo-tiff into a form that Altus can use. You can download AltusRaster by: a) going to http://builds.ba3.us, b) click on the latest build, c) download the binary RPMs for CentOS7. If you type "install an rpm on ubuntu" into a search engine, you will find that it takes just a couple of commands to install AltusRaster.
- The geo-tiff from the FAA is in indexed single-band color-space. AltusRaster needs the data in a 4-channel color space (RGBA). You can run this command to produce the file in the needed format:
gdal_translate -expand rgba -co COMPRESS=LZW Charlotte\ SEC\ 99.tif CharlotteRGBA.tif
This will convert the Charlotte chart. Change the name for whatever chart you want to convert.
- Now you can run AltusRaster. Create a new directory called CharlotteTiles (or whatever you wish to call it) and use this command to run AltusRaster (AltusRaster -h will describe all of these options):
AltusRaster -ml 12 -fa lanczos -i CharlotteRGBA.tif -of CharlotteTiles
When you run AltusRaster, note the coordinates of the map's bounding box so you can use them in the code.
- The CharlotteTiles directory contains the tiles for the FAA chart. Move them to a web server. Now they are available for downloading to an Altus app or web application, as demoinstrated in this example.
Maps: © Mapbox © OpenStreetMap