Ever felt like Google Maps doesn't provide enough detail of the aerial view of your neighbourhood? Ever wanted to make your own maps or participate in a little homegrown science? Balloon mapping is a cheap way to take aerial pictures for all sorts of purposes -- even events like weddings, graduations or parties -- and it's dead simple to do it yourself. Here's how it works.
Title video music by Symfoniorkestern.
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. 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
Balloon mapping is an old-fashioned and simple approach to aerial mapping, so your materials list isn't very complicated. You can put together your own DIY kit for around $US70, or purchase the official Public Laboratory recommended kit for $US115. To keep things on the up and up, we chose the official kit. Here's what you get in the kit:
• 1.67m reusable balloon • 1000m of unbreakable string • Protective gloves • Swivel clips for attaching the camera • Carabiner • Rubber bands for the camera • Zip ties • One 1-inch ring for attaching the balloon
In addition to what you get in the kit you'll also need:
• Any point-and-shoot camera with a continuous or "sport" mode where you can hold down the trigger and it will take pictures until the memory is full • One SD card (4GB recommended) • One 2L soft drink bottle (or some plastic enclosure) • 2.26cubic metre canister of helium
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 neighbourhood.
Set Up and Launch the Balloon
Launching 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
Before you launch the balloon, you have to decide on a safe place to do it. In my case, that meant launching it off the roof of my apartment so it wouldn't get tangled in power lines. This meant I couldn't walk around with it, and that narrowed the amount of ground I could cover.
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 8km/h) or rainy. I had to delay my flight twice due to thunderstorms, so plan ahead. When you've got everything organised, it's time to fly your balloon.
Step 1: Prepare Your Camera Rig
You don't want to launch an unprotected camera into the sky. The best option? The top half of a two-litre 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. 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
With the camera ready to go it's time to fill the balloon with helium. Start by placing the one-inch ring over the tip of the balloon. Next, wrap the balloon tip over the helium container, tie it down with a zip tie, and then fill it up. When the balloon gets to about 1.2m wide attach the camera and see if the balloon can lift it. If it does, you're done; if it doesn't, reconnect the balloon and keep on filling. It took me around 15 minutes to fill the balloon.
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 of 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
Now it's time to send your balloon mapping kit into the air. Grab your camera rig and tie it to the string or directly to the balloon (I attached my camera to the balloon because I didn't trust my knots, but ended up with the string in most of the aerial pictures). Pull down on the rig to make sure it's secure and the camera isn't going to fall.
You should now have a balloon that's about 1.2m 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 metres, then it's taking pictures of about 1000 metres 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
When you're happy with the amount of ground you've covered, start reeling the balloon back in by wrapping the spool back up. This took me around 15 minutes to get it all the way back, so be prepared to wrap for a while. However, if you plan on reusing the string, take the time to reel it in right to avoid tangles.
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 to see if 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 your pictures together.
Stitch Your Images Together with MapKnitter
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 web app 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 drink 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 neighbourhood, 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.