Watching the average Hollywood action-espionage-thriller, you’d be forgiven for thinking that governments can use vast constellations of spy satellites capable of infinitesimal resolution to track your every movement, identify your car numberplate and read the newspaper from right over your shoulder... all in glorious Technicolour. Unfortunately, science fiction sells more movie tickets than science fact, so these films owe more to Star Trek than Silicone Valley.
Nevertheless, the resolution of these kinds of sensors are improving. In June 2014, the US Government relaxed resolution restrictions on the sale of satellite imagery, enabling satellite operators to provide 30cm GSD imagery to the commercial market for the first time. This means that pixels from some satellites will cover an area on the ground measuring 30cm x 30cm, or 900cm2.
How does that compare with 5cm aerial imagery? Well, for a start, the difference is not linear, it's exponential - 5cm resolution is not six times ‘better’ than 30cm resolution. Each 5cm pixel covers a ground area of 25cm2, so the improvement in clarity is actually 36 times, not six. That kind of improvement is the critical difference between guessing and knowing.
Of course, satellites have advantages that make them important for certain applications, like mineral exploration, disaster response and large-scale environmental monitoring. They’re capable of capturing images from an orbit hundreds of kilometres above the earth while travelling at 7 kilometres a second, delivering an imagery footprint that is 10-15km wide, which can be revisited daily but is inaccurate compared with aerial platforms. Current generation satellites can also capture using multispectral sensors that collect imagery in the visible, Near Infrared and Short Wave Infrared areas of the spectrum. Some satellites can also render imagery using ‘superspectral’ sensors that correct images for atmospheric interference from cloud cover, ice and snow, water vapour and aerosol.
It’s an impressive capability, but you’d expect “impressive” when you’re spending upwards of US$650 million to design, develop and deploy a commercial satellite. More recently, lower orbiting satellites have been deployed at about 5% of that cost. While the imagery output may only have a resolution of just under 100cm, these satellites capture black and white 1080p video, which can be made available in clips of up to 90 seconds long, ideal for the realtime analytics sector. These kinds of innovations are bringing welcome disruption to a sector that has been dominated by a small number of incumbents with deep pockets, multi-year development cycles and legacy technologies.
Will satellites ever replace aerial photography? Unlikely, as the cost of the 15cm resolution KH-11 military satellites as used by the US National Reconnaissance Office is estimated at US$2.9 billion, simply far too expensive for a commercial operator to achieve a return in competition with much cheaper, significantly higher resolution aerial imaging technologies.
The ultimate winner is, of course, you. As a consumer, you have more choices than ever when it comes to geospatial imagery. At Spookfish, we’re confident that our technology offering occupies a unique space and satisfies a significant number of market sector applications:
- large-scale acquisition of accurate 2D and 3D data at high resolution;
- captured, processed and published in days;
- frequently and reliably updated; and
- made available at a cost that is within reach of organisations large and small.