May 17th, 2012Top StoryHow to Balloon Map Your Neighborhood, Google Maps StyleBy Thorin Klosowski
Balloon mapping is a means to create low-cost and high-resolution aerial maps. Essentially, you fill a large balloon with helium, attach a camera to it, and then let it fly over the area you want to see. When you're finished you can stitch the images together to create a large aerial map. You can take it a step further by submitting to the open source community Public Laboratory so others can see and even add to the maps you create, and if you do a good enough job, your images might even make it into Google Earth. At a glance balloon mapping might seem a little eccentric, but on top of being a fun way to spend an afternoon, it has its uses. On one hand it's a bit of counter-cartography to rival Google Maps so you can map and explore your own environment. It's also a great way to document big changes in the landscape that satellites simply can't do. Balloon mapping has been used to document the BP oil spill, the Occupy Movement, and to provide an aerial view for environmental campaigns. I ran through the whole process myself and launched a balloon off my roof. It's pretty simple and the process is split into three essential parts: gathering supplies, launching the balloon, and stitching together the images your camera gathers. You can watch a quick overview in the video at the top of this post, but let's walk through each step in detail below. The Supplies You Need
In addition to what you get in the kit you'll also need:
All of the materials besides the helium are reusable, so once you buy the kit (or make your own) you'll be able to continue using it for as long as you like. With all that in tow let's launch the balloon into the sky and get a view of the neighborhood. Set Up and Launch the BalloonLaunching the balloon is surprisingly easy, but you do need to make a few preparations ahead of time and keep yourself safe throughout the process. Before you start, be sure to read all the official guides and print out a checklist so you don't miss any details. Step 0: Preflight Preparations
Once you decide on a location, make sure it's not within five miles of an airport and brush up on the FAA regulations in your area. In most cases you can launch without too much worry, but it's still good to know the rules. Finally, make sure your camera's battery is charged and your SD card is empty. Check the weather for your flight day to make sure it won't be too windy (over 5 MPH) or rainy. I had to delay my flight twice due to thunderstorms, so plan ahead. When you've got everything organized it's time to fly your balloon. Step 1: Prepare Your Camera RigClick to view You don't want to launch an unprotected camera into the sky. The best option? The top half of a 2-liter bottle is a great camera shield. For larger cameras you might need to experiment to get the right size—I found a slightly larger apple juice container worked for a Nikon P80. Once you have a container that your camera fits in you need to find a way to force the trigger down. I did this by finding a small pebble and securing it to the trigger with a couple of rubber bands. This makes it so your camera will automatically take pictures when flying through the air. Finally, you need to secure the camera inside the container. If your camera has a strap you can do this by pulling the strap through the top and you're done. If you don't have one you need to wrap string around the camera and pull it up through the top of the bottle. This is the part you'll connect to the balloon so make sure the camera is secure. Step 2: Fill Your Balloon with Helium
When the balloon is full and has enough lift, fold the tip of the balloon in half with the ring in the middle and use a couple zip ties to secure it shut. Finally, tie the string spool to the balloon with a good knot and then tie the end of the string to something secure on the ground. This process is a lot easier with two people, so grab a buddy if you can. Step 3: Attach Your Rig, Start Your Camera, and Launch
You should now have a balloon that's about 1.2 meters in width floating above your head with a camera attached to it and the ring on the balloon attached to your spool of string. Give everything a once-over to make sure your knots are secure and then turn your camera on. Double-check to make sure the camera is taking pictures and you're ready to launch. Put on your protective gloves (seriously, you'll get a wicked rope burn if you don't) and grab the spool. Release the balloon from whatever you've attached it to on the ground and let the balloon rise quickly. Now just let the balloon float to a desired height while the camera takes pictures. If the balloon gets up to around 1000 meters then it's taking pictures of about 1000 meters of the ground. If you can (and I couldn't do this part unfortunately), walk around with the balloon so you can map a larger area. For the most part you won't find a "right" or "wrong" way to capture images. You can keep the balloon closer to the ground and get very high resolution shots of your location or you can let it drift up high to get a wider view. Step 4: Reel the Balloon Back In
Once the balloon and camera are back in your hands, tie the balloon to the ground again, take the camera off the balloon, and then check and make sure it was taking pictures the whole time. If it did, you're done. You can either slowly let the air out of the balloon by removing the zip ties or save the balloon for another flight tomorrow. Now it's time to head inside with your SD card and start stitching you pictures together. Stitch Your Images Together with MapKnitterClick to view Now comes the not-so-fun but necessary part: stitching all your photos together to make one large map. This is done with the free webapp MapKnitter that compiles your photos together on top of a Google Map satellite image to create a seamless, high resolution photo. On your SD card you probably have upwards of 4000 aerial photos and a number of them will be identical. With that in mind, grab yourself a nice beverage and start going through all of the photos to pick out the ones that have a clear, straight-down shot. You only need one shot per area, but make sure it's a good one. The video to the left guides you through the whole process, and although it's time-consuming, it's not difficult. It will take a lot of trial and error, so start small and take it slow. When you're done you'll have a high resolution aerial image of where you mapped. You can get a look at my still-in-progress map over on MapKnitter (and embedded below). My stitching skills still need some work and I'm waiting for a day with a good northeast wind to get the other side of the neighborhood, but you can get an idea of how it works from my images. For a more detailed look at every step, check out the Public Laboratory's consistently updated collection of guides, videos, and methods. How you use balloon mapping is of course up to you, so if you have any ideas, thoughts, or questions be sure to share them in the comments. Title video music by Symfoniorkestern.  |
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