Pathfinder is a flight path and image acquisition visualization package for a near-space balloon.
HackPittsburgh has launched several high-altitude balloon projects. Most launches carry a camera that takes photographs at a defined interval, and all launches carry position-tracking hardware and software that communicates with ground-based stations such that the balloon's flight path is recorded.
This software package, written in Processing with some supporting Python scripts, attempts to visualize the balloon's flight by presenting the recorded images together with a rendering of the balloon's flight path in synchronized, accelerated time.
Previous balloon launch photos are available at the HackPittsburgh Flickr Pool. My favorites, plus my ground photos, are at my Flickr page.
- Processing 1.2.1 or higher (http://processing.org)
I've tested Pathfinder with Processing 1.2.1 on Mac OS X 10.6.4 and 10.7.2 and with Processing 2.0.2 on Mac OS X 10.8.4 and on nothing else.
- Python (http://www.python.org)
- EXIF.py (http://sourceforge.net/projects/exif-py)
I've tested the tools with Python 2.6 and EXIF.py 1.1.0 on Mac OS X 10.6.4 and on nothing else.
No installation is specifically required to run this app short of placing the
source files and the contents of the data and helper subdirectories in a
subdirectory of the Processing sketchbook named Pathfinder.
To use the helper scripts, Python must be installed following the instructions at the download link. In addition, the required Python dependencies listed above must be downloaded and placed into the Python module search path. The use of the helper scripts is not required to run Pathfinder. More information regarding their function is provided below.
The images used and displayed by the app are not part of the git repository due to their size. Therefore, they must be downloaded and the input image catalog may need to be regenerated.
The pre-built image catalog and balloon path data that are a part of this git repository come from LEAD Balloon A2. The balloon path data is not preserved on the tracking site forever, but it has been post-processed and checked in to this git repository. So, as written, this particular program will only work for visualizing LEAD Balloon A2's path.
To obtain A2's images, they may be downloaded from my Dropbox archive.
Place the images into the data/images subdirectory. The balloon's path data
is already present in the data directory, as is a catalog file containing the
timestamps and filenames of the images contained within the archive above.
- Open Processing
- Open the Pathfinder sketch from the sketchbook
- Press play
There are no real controls for the app, it should simply play through the balloon's still frames while rendering the specific point in the balloon's flight path corresponding to the balloon's position at the time the frame was taken.
Using this application for other balloon flights may be possible but will require a capture of the balloon path data as well as regeneration of the CSV files that give timeline, location, and image data to the application.
Ensure that the required dependencies are installed as identified in the Requirements section.
Find the callsign of the balloon to visualize. The callsign may be found at the balloon's flight page on the HackPittsburgh wiki's LEAD Balloon Project Page.
Once the callsign is determined, visit the aprs.fi website
and select the Data Export Tool. Enter the balloon's callsign and flight
window, then download the balloon's flight path data in Excel/CSV format. Place
this file in the data subdirectory of the Processing sketch, and ensure that
the name of the file to load in the code and the actual filename on disk match.
Obtain the balloon images to be included in the visualization. Typically this will be via the LEAD Balloon Project Page or the HackPittsburgh Flickr Pool.
Place the images in the data/images directory. Use the exif2csv.py script
provided in the helpers directory to generate a CSV file containing the
timestamps and names of each of the image files. The script has instructions
for use embedded within it. The resulting CSV file should be placed in the
data directory.
The CSV file will contain EXIF timestamp data extracted from the photos in the
data/images directory. This timestamp data is used to synchronize the display
of the photos with the display of the balloon path in the app.
It is possible that there will be a mismatch in time zone between the balloon
flight path data timestamps and the camera EXIF data timestamps. The
dezulu.py script can be used to adjust the timezones by a fixed offset.
No unit tests are provided with the source distribution at this time.
To uninstall Pathfinder, simply remove the Pathfinder directory,
subdirectories, and files from the Processing sketchbook.
For the helper scripts, the Python dependencies may be removed from the Python installation's module search path, and Python itself may be uninstalled.
There are a few things I'd like to do but will never get around to:
- Make the orientation of the path rendering prettier
- Overlay the rendered flight path on an actual map of the location
- Add controls to rotate the flight path in three-dimensional space
- Add controls to change the speed, pause, restart
Jon Speicher (jon.speicher@gmail.com)
The exif2csv helper script depends on EXIF.py by Gene Cash, Thierry Bousch, and Ianaré Sévi.
The MIT License
Copyright (c) 2010 Jonathan Speicher
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
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copies of the Software, and to permit persons to whom the Software is
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The above copyright notice and this permission notice shall be included in
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