Real Technology, Real Benefits,
part 3: image quality

Real Technology, Real Benefits is a series of articles that explores the connection between satellite imaging technology and real-world applications and benefits. Read Part 1: pointing agility and Part 2: revisit rate & collection capacity.

In parts 1 and 2 of this series, we discussed the various technical factors that determine whether a satellite constellation can collect the imagery that you need, when you need it. Now let’s focus on what you can do with that imagery once it’s acquired.

A few millennia ago, Socrates said, “Man must rise above the Earth, to the top of the atmosphere and beyond, for only thus will he fully understand the world in which he lives.” We know now those words were incredibly prescient. Data provided by space-based instruments play a meaningful role in our everyday lives, from predicting the weather, to enabling our navigation, to monitoring agricultural crops and giving our military forces an information advantage.

The satellite constellations that have endured over time, evolving with successive generations of technology, are those built to meet specific needs, such as weather observation, communications, positioning, and high-resolution imaging. The image below was captured by Himawari 8, a Japanese weather satellite built to continuously monitor weather phenomena across the entire Pacific Ocean region.

Earth
Courtesy of the Japan Meteorological Agency

One of your first reactions to that image may be simply how much of the earth is covered by water and clouds. This may be obvious, if you know that land accounts for roughly 30% of the earth’s surface area, and nearly 60% of land is covered by clouds at any given time.

If water and clouds are among your primary interests, like Himawari 8, that’s no problem at all. For high-resolution imaging satellites like those operated by DigitalGlobe, water and clouds are of very little interest to customers. As discussed in the previous blog posts, that’s one of the reasons our satellites were built with large telescopes and high agility — to photograph cloud-free land areas as much as possible and show what might otherwise be hidden.

So let’s consider the optimal scenario for satellite imagery users: your commercial provider of choice gets a cloud-free image of the area you need at the time you need it. For the following comparisons, we’ll use a Planet Labs image of Sydney, Australia, taken on the same day as the image of Sydney that we shared in our last blog post. At a city-level view, the Planet Labs image (left) and the DigitalGlobe image (right) are both spectacular – after all, Sydney is one of the world’s most photogenic cities.

Image on left: © 2016 Planet Labs Inc., downloaded from the Planet Labs gallery and licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

But city-level views of earth have been around for decades and are freely available from government satellite programs such as the United States’ Landsat and Europe’s Sentinel-2. For commercial satellite imagery to have value to paying customers, it needs to contain a level of detail that allows for decisions to be made. The concept of imaging every place on earth every day with microsatellites is certainly compelling, but it starts to shift once the realities of economics and physics come into play. Specifically, things that can be seen at 3-5 meter resolution, like corn fields and buildings, don’t typically change every day; and things that do change every day, such as the size of a crowd in a plaza, the number of vehicles on a road, and the amount and type of cargo in a port or harbor, can’t be seen at that resolution, and moreover often change much more frequently than daily.

When we zoom in to the docks of Woolloomooloo Bay, the real differences between high- and low-resolution commercial imagery become apparent. On the left, it’s hard to tell how many ships are present, or if they’re even ships; on the right, the types and configurations of the military vessels can be determined, with radar domes, antenna arrays, helicopter landing pads, and armaments clearly visible. Having this information is essential for military and intelligence users who need to decide whether and how to deploy resources, particularly when lives are on the line.

Image on left: © 2016 Planet Labs Inc., downloaded from the Planet Labs gallery and licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Heading over to Bondi Beach, the DigitalGlobe image on the right reveals all sorts of information not contained in the other image, such as the presence of people on the beach, the number of cars in the parking lots, and the level of commercial activity at Bondi Pavilion. These types of information are useful for organizations such as financial institutions and global development organizations that need to understand demographic and economic trends, from the local to the global scale.

Image on left: © 2016 Planet Labs Inc., downloaded from the Planet Labs gallery and licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Now let’s check in on the Darling Harbour redevelopment project. In the DigitalGlobe image on the right, the fine details allow progress to be monitored on the construction of a new convention center and expansion of a city park. City managers leverage high-resolution imagery to develop resiliency programs, assess tax burdens, and inform budget projections.

Image on left: © 2016 Planet Labs Inc., downloaded from the Planet Labs gallery and licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Finally, we’ll tour the attractions around Cockle Bay. Imagine viewing the scene below on your phone’s mapping app. Is there parking in that area? Where is the Ferris wheel that someone told you about? Is that an animal zoo with a glass roof in the top right of the image, or an empty lot? For consumer applications, these are essential details that only DigitalGlobe can provide.

Image on left: © 2016 Planet Labs Inc., downloaded from the Planet Labs gallery and licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Spend some time exploring other areas of Sydney with this interactive comparison tool.

The examples above show how lower resolution imagery is generally less optimal for most national, enterprise, and consumer-based applications, particularly those that need to make decisions with confidence. However, stand by for the fourth and final blog post in this series to learn how multiple sources of data can be synergistic, when you pick the right tool for the job.

Dr. Walter Scott is DigitalGlobe’s Founder and Chief Technical Officer.