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Posted by on Aug 1, 2012 in Mapping, What's new | 0 comments

Balloons, Drones and Satellite Images

Balloons, Drones and Satellite Images

Essential for getting an overview in the field – now in Do It Yourself format

Technologies to capture a Bird’s Eyes view have been around and used in the humanitarian sector for a while. Be it for getting an overview of the situation on the ground pre and post emergency to assess the changes, for monitoring crops or for population and camp mapping, the benefits of using airborne images have been widely demonstrated.  However, whereas Satellite Images and Remote Sensing techniques or aerial photographs and photogrammetry show great results when applied by experts, there are certain challenges when planning to use them as a layman.

First of all, this is not a budget solution, despite the fact that there are initiatives like SAFER, now GMES Initial Operations, or GIO, which allow dissemination of images and remote sensing products at a reduced cost or even for free. Second, tasking the satellite, e.g.  pointing it to the area of interest at the time the satellite passes, or organizing a helicopter flight-over with a professional aerial camera on board can be logistically challenging or even impossible depending on the situation.

However, new solutions with a Do It Your Self and Suit Your budget Touch have entered the market in the last few years. Some of them require more efforts from the user but are more economical than others. An example for a user friendly tool which requires little setup but is more costly would be the usage of high-tech small scale drones like designed by SenseFly, a Swiss company. Formerly known as tools for military purposes, they have increasingly been used for civil applications as well, especially in the area of natural disasters, but also for agricultural applications like the monitoring of irrigation schemes for crops. One of their products has been successfully piloted by UNOSAT in Haiti in 2012. UNOSAT issued a press release on their intention to increasingly rely on Unmanned Aerial Vehicles or UAV, the abbreviation commonly used for drones.

Another new technology is based on mounting balloons and blimps with cameras. The main difference between balloons and drones is that the balloons are stationary unless you walk with them on the ground, keeping them on a leash. The drones follow a flight path which is either programmed before takeoff or is communicated remotely through a transmitter while in flight. Both options have advantages and disadvantages.

Whereas the balloons are often referred to as being less intrusive and in many situations won’t need a permission to get launched, they require helium and take pictures with a wider range of angles than the drones. The latter can be a decided advantage when mapping in 3D since it allows creating spherical models. However, if your only objective is covering a wide area with near vertical pictures to create orthophotos then it will be easier to achieve this with a drone.

There is a Spanish NGO, APDER, working on balloons and blimps and they have compiled resources on the technology and showcase some of the products on their webpage. You can peruse their spherical models created in their 2012 Haiti pilot.

However, if you are just interested in using the DIY option, you can purchase a kit from Grassroots mappers. They have also assembled resources and tutorials for DIY Helium balloons and kites. A set goes for less than a 100 USD (without camera) and the funds are used towards making the technology available to grassroots organizations anywhere in the world. So you get to play around with your own kit and at the same time you are supporting a good cause.

CartONG has tested the kit.

Balloon Mapping

 

Whereas it looks easy to assemble, we run into difficulties of getting the balloon really airtight and holding the helium for long enough. And then another issue is getting a simple digital camera securely attached and taking continuous pictures while being focused. Wind can pose a problem as well. We decidedly let it rise with too much wind and did not pay close attention to set the auto focus to infinity. The helium was easy to obtain but the costs are not trivial, one balloon fill was around 43 EUR. Ordering over the internet can cut the costs, though delivery of the heavy gas bottles needs to be thought of as well. However, next time we make sure that we get the balloon to hold the gas longer so that several areas can be photographed and explored from above over a weekend. That will reduce the costs considerably. A new set of lessons learnt. We hope we will be able to post real focused bird’s view pictures after our next attempt. :-)

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Figure 1: Balloon already a few meters up, camera starting to un-focus :-(

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This article has originally been posted in CartONG’s July 2013 newsletter.

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A propos de l'auteur :

Sandra Sudhoff

Sandra joined CartONG in 2007 and is now technical director of the NGO. Originally a Landscape Planner with a Specialization in GIS and Remote Sensing, she worked on a wide range of topics and tools and gain a thorough understanding of the humanitarian sector.