Remote Sensing 101
Airborne Remote Sensing describes a suite of technologies that use overhead photography, sensors, and satellites to create detailed maps and measurements. There are two types of remote sensing technology: Passive Remote Sensing (or Photogrammetric remote sensing) - The collection of reflected light in the form of color or RGB (red/green/blue) pixels that form photographs. Active Remote Sensing - Emits energy that measures the time it takes for that energy to reflect, creating a 3-dimensional dot that is recorded as a node in a point cloud.
Let's start by addressing the big question - what is Remote Sensing?
Remote Sensing and Photogrammetry first started with the use of flights and balloons taking early images of the ground below. The remote sensing service that we know today started back during WWII evolving throughout the Korean and Vietnam War, for military planning and operations. The first Photogrammetrists started their careers out of the military, where they were trained to identify military assets and facilities through Remote Sensing. Individuals would draw out the contours of a site, trace with a pencil, draft in ink and/or scribe the contours of the location to make a map. Creating a map could take weeks to complete and was a very time-consuming and expensive process. Fast forward a few years and technology started to grow out of the military and into the private sector. Not all who worked in photogrammetry came from a military background, however.
How did Photogrammetry/Remote Sensing originate?
As we know, technology is always changing. So, do we use the same process for remote sensing now that we did over 50 years ago? Absolutely not! We’re using faster technologies, computer software, drones, and even piloted airplanes. What was once taking weeks to complete, can now be done in ~8 hours or less depending on the project site. The great thing about technology is that there is always something new, better, and faster around the corner. However, that doesn’t always mean that we have access to it. For example, drones are driving the future, but there are significant airspace restrictions. Did you know that you can’t operate a drone outside of line of sight? This is known as beyond visual line of sight (BVLOS) restriction. You can’t fly over people or moving cars, making the option to fly a drone a great choice for an underdeveloped plot of land, but not so much for an area with lots of people and traffic. For populated areas and everything in between, a site can be flown with a fixed wing airplane. A manned airplane with a pilot and a camera-man can be flown anywhere with less restrictions when compared to a drone for great photogrammetry results. Thousands of acres can be shot in a day by using a manned airplane.
How has technology played a role in Remote Sensing?
Remote Sensing can be used on any job site, really coming in handy with very large project sites. An area that could take a field crew multiple hours and days to complete a traditional survey can be flown in just a few hours. Not to mention, the cost of remote sensing is cheaper than traditional survey because of the processing and time savings.
What makes Remote Sensing such a great service option?
UAV (Drones)
Low cost, very high resolution, detailed access to hard to reach areas, perfect for surveying mining, landfill, and construction sites. Drones are a great fit for small sites with limited vegetation.
Manned Aircraft
Great for large areas, use if you need to fly over people or moving cars.
Library of Images
A repository of images of sites flown in years past. Useful if there have not been many updates to the job site since the original imagery was processed.