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Balloon Mapping Summer Fun

Posted by Ed Roworth on Jul 22, 2013

While many of the Critigen team were headed for the Esri International User Conference in San Diego, Critigen Innovator Ed Roworth was exploring DIY balloon-based aerial imagery acquisition, and training the next generation of geo geek at the same time

Balloon MappingWith summer in full swing it’s a good time to get outside and do something fun with the family. How about flying a really big balloon with a camera underneath and mapping your favorite park?

Aerial photography and photogrammetry have always been an integral part of GIS. In fact, high quality aerial photography or satellite imagery is likely to be the base of all subsequent planimetric features that enhances a map’s context. Our maps really can’t do without current road centerlines, building footprints, or other related features. The downside to this reliance is the need to collect imagery on a frequent basis to keep these layers up to date. It would be perfect if we could rely on our favorite web mapping providers for this. However, it could be a long wait and it might not be the resolution we need especially if we just need to update a small area the size of a park or new construction area.

Balloon MappingThe Public Laboratory for Open Technology and Science (Public Lab) is now selling a balloon mapping kit. This kit, along with your own store bought digital camera and a tank full of helium will get you started. Public Labs’ provides plenty of documentation and additional help from their YouTube videos. With a little bit of prep work to setup the kit and your camera you’ll be ready for launch in no time. If you have an old Canon camera lying around, you can hack it to take pictures at defined intervals. Perfect for taking pictures that overlap and don’t use up your entire memory card. The hardest part of the whole setup is finding a helium tank with at least 30-35 ft3 of gas for one flight of the big balloon (I got mine from Praxair).

Balloon MappingWith balloon, helium and an assistant in tow, I headed for the park to launch. Ideally, I would have liked to let the balloon up 500-1000 feet in altitude (any higher than 1000 feet and you need to contact your local airport). With a nice breeze in the air I had to keep it to a lower altitude (~350 ft) since the camera would swing back and forth resulting in blurred or nice oblique photos.

Balloon MappingAfter walking the full park and battling the slight breeze to guess about coverage and overlap, I had collected over 250 photos in a few hours. For post processing I selected and georeferenced the best of the bunch resulting in the final mosaic of 30 images with almost complete coverage. There were some gaps where I missed overlaps, but for my first time out I’m pleased with the results. Certainly good enough to do feature extraction of the parks planimetrics.

Balloon MappingFor the georeferencing workflow I elected to use Esri ArcGIS for Desktop since I had done this many times in the past with true aerial photography. The 2nd order polynomials proved helpful with some of the obliqueness when the camera was swinging. I highly recommend checking out Esri’s home use program if you want a great professional package at little cost and are doing this for fun.

The idea of collecting your own DIY aerial photography without sophisticated and expensive equipment is hard to pass up. The real world accuracy is likely 3-10+ feet in most places. I say likely because obviously this is not professionally flown at a controlled altitude, 2/3rds overlapped, orthorectified and quality controlled with a 3 inch accuracy report. But in certain circumstances where precision is less important and professional aerial imaging is cost prohibitive, this could be a viable solution. In any case, it’s a great way to teach the kids a bit about GIS and a great excuse to spend some quality time outdoors.

Of course, if you’re working environmental remediation, civil infrastructure or other serious projects, Critigen’s Geomatics, Survey and Mapping team have licensed and certified professional who collect, control and map your project sites with resource or survey-grade equipment and deliver a professional product.

Author Info

Ed Roworth, Municipal GIS Solutions, NYC GIS
Ed Roworth
Local Government Solutions
+1 610.873.1941

With decades of experience implementing GIS systems and solutions for clients, Ed's keen insights at the intersection of technology and business applications shed light on the impact new technologies and approaches can have on the GIS industry and the industries using GIS.