Combining On The Ground Science With Satellite Remote Sensing

PlanetWatchers
Mar 5, 2018 · 5 min read

It Really Is the Little Things

I grew up spending all of my free time outdoors, whether it was working at botanical gardens in New England (before I knew the differences between the plants), planning renewable energy projects in California or building hiking trails in Utah, the central facet of these experience was my hands were dirty and my boots were muddy. Being on the ground in front of something has a powerful impact on seeing the details. It’s like going to a new city and exploring by walking instead of by car, you will invariably find that hole in the wall restaurant on foot and drive right past it in the car.

Liriodendron tulipifera, more commonly known as the tulip tree, is my favorite tree and has been since I learned how to identify trees. I appreciate the intricate subtleties required to practice this skill and become an expert of tree identification, namely the examination of minute details only seen from a close up inspection. For the tulip tree, the defining characteristics for me are the bright yellow buds, the seeds (which resemble miniature surfboards) and the leaves. I find these leaves fascinating. They are unlike any other leaf in my opinion due to the irregular shape of four swooping points connected by symmetrical curves.

(Left) The leaf of the tulip tree and (Right) location where the author worked on restoring public trails.

Knowing these details about trees and seeing them up-close and in person definitely helps to identify numerous species as well as to identify disease or pest damage. To scale up this direct examination across an entire forest or ecosystem is highly impractical in terms of time and cost. Even drones, which are increasingly popular in many sectors, can cover only a few square kilometers of forest in a day.

On the other hand, one can survey an entire forest quickly and accurately using remote sensing technologies such as satellite-based optical and radar imaging. Satellites cannot make out the shape of leaves but they can provide valuable data such as the growth rate and the health of a stand of trees. While both on-the-ground and from-the-sky data collection methods are useful, to get the most robust picture of forest health, requires a combination of the two viewpoints.

A Crash Course in Radar Remote Sensing

Radar as a remote sensing tool is referred to as ‘active’ sensing in that electromagnetic microwaves are sent out from the satellite and the returning signal is measured. This is in comparison to ‘passive’ sensing where the energy naturally reflected from a source is analyzed, such as sunlight in an optical image.

Due to the long wavelength of the electromagnetic microwaves that are sent out and returned, radar is not reliant on clear atmospheric conditions it can see through clouds or haze, and can be reliably collected at regular points in time. Because radar is not reliant on reflected sunlight, it can operate at night. Radar allows PlanetWatchers to plan out when new information will be collected and not be hindered by night or clouds, as with many other companies attempting to do the same analyses.

This is where remote sensing, and more specifically radar imaging, can monitor vast geographic scales while still detecting changes or disturbances that are important for conservation efforts, carbon storage and land management operations. At PlanetWatchers, we utilize multiple sources of satellite imagery including optical (think Google Earth) and radar.

I will now briefly explain the merits of using radar as a tool for combining on the ground science with remote sensing. For remote sensing, it is important to incorporate on the ground science in order to calibrate and train our algorithms as well as to validate our results. By validating our results, PlanetWatchers continuously trains the algorithms it develops to ‘learn’ how to identify and categorize various items. Over time, the system becomes more accurate and efficient in monitoring natural assets.

At PlanetWatchers, we are developing algorithms and analytics platform to track changes in anything from forests and crops to pipeline failures and insurance risk. I knew that these fronts would be on a massive scale, but I did not realize that 100,000 acres and up would be an everyday target. I fully understood the impact we are making at PlanetWatchers when I performed my first field visit to one of our monitored forests and realized the potential when precise changes were detected in growth.

(Left) An example optical image and (right) a radar image of the same area. Radar has the ability to see through the clouds and at night, this radar image was captured at around 9 pm.

It was incredible to validate what our remote sensing technology was capable of detecting over time. We could use our system to pinpoint exactly where we expected certain changes to be located, walk to that spot and bingo, just as we suspected. I appreciate the up close and personal ecology that I had grown up with more now that I know its possibilities when combined with macro-scale remote sensing analytics.

What Happens When the Little Details Are Actually the Big Details?

Now that we know the importance of the little details in natural resource management and the technical abilities of radar, what happens when you combine the two? When you are able to analyze the little details across the large scales, you are no longer reliant on models but rather, the data itself. With more and more data available surrounding natural resources, the benefit of making decisions based on actual measured information far outweighs the previous method of scarce sampling. These benefits will only become more important as our climate continues to change as a result of anthropogenic factors.

I enjoy the fact that I can still analyze the small details of the trees I have come to appreciate so much, and now on a scale I could only imagine before. This combination of on the ground science with satellite remote sensing is opening up a world of possibilities for monitoring the natural resources that we all share. I hope that more and more entities come to understand the value of not having to sacrifice the little things for the big things because when you think about it, what are the big things really made of but a lot of little things?

About the Author

David Markowitz works at PlanetWatchers, a radar-based analytics startup in the world of remote sensing and natural resource management aiming to disrupt traditional satellite uses. He is responsible for analyzing the science behind various avenues for applying this novel technology and acquiring new users. David holds a B.S. in biology from Carnegie Mellon University and an M.S. from the University of Michigan. When he is not writing about remote sensing, David can be found hiking and stopping to look at every tree along the way.

PlanetWatchers Monitoring Blog

Last mile of analytics for companies that manage and protect natural resources.

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PlanetWatchers Monitoring Blog

Last mile of analytics for companies that manage and protect natural resources.