How About Letting Your Raspberry Pi Take Pictures of the Earth?
Many many years ago, before cameras came to be associated with lenses, people captured images on film using a pinhole on the camera. This technique is still in use today. It’s called heliography and it requires long to very long exposure times – sometimes as much as 24 hours to six months. The results are rather stunning, as you can see.
Unless you have photography as a hobby, you may not be able to spare much time and may not have equipment suitable for heliography. However, taking pictures of the earth is quite an exciting project, and since you have Raspberry Pi, why not let the tiny Linux computer do it?
That is exactly what Dave Akeman planned to do. He created the Raspberry Eye-in-the-Sky project that sent Raspberry Pi and a bunch of components out into the atmosphere where the weather balloons go and burst themselves. The payload consisted of a Raspberry Pi, a camera and a tracker, powered by a few AA batteries. The pictures, taken while the camera was in the sky, are spectacular and amazingly crisp.
Dave changed the regulator on the Raspberry Pi and modified it so the computer could work on 3V instead of 5V, to allow the batteries to last longer. He embedded the entire electronics in a foam replica of the Raspberry Pi logo, with the camera peeping out from the bottom. The foam was for softening the landing of the package when it hit the ground after the balloon burst. Dave also put in a parachute so the package would come down smoothly.
Dave had to take permission from the CAA for the Hydrogen balloon that would carry his Raspberry Pi camera payload into the atmosphere. He used the latest Pi camera software and changed the code to make it take three types of images each at about one minute interval. One small image is taken for the first radio channel, one medium image for the second radio channel and one hi-resolution image is stored on the SD Card onboard. Additionally, Dave configured the camera to work in matrix-metering mode instead of spot metering, as this gave better resolution images.
The balloon and its camera payload went up one sunny morning, near Tetbury, UK. People from France, Holland and Northern Ireland monitored the Raspberry Eye-in-the-Sky broadcast. The image quality throughout the 3-hour flight time was excellent. The flight path, with the wind guiding it, had quite a few changes of direction and some loops. The package went up to about 24.5 miles in height finally landed near the city of Swindon about 22 miles away from Tetbury.
As the launch was delayed by more than 2 hours, the Raspberry Pi package missed the original predicted landing spot, since the wind pattern had changed in the meantime. In addition, a resident of Swindon found the package as it landed near him, and took it home. He then called up Dave after finding his telephone number on the package. That solved the initial mystery as to how the Raspberry Pi package travelled to another location after it had landed.