Headwall Photonics Blog

Hyperspec SWIR Gets UAV Wings!

Posted by Christopher Van Veen on Thu, Sep 14, 2017

Remote sensing with hyperspectral sensors is  a combination of several elements: an imaging spectrometer and a fast data processing system to acquire and analyze spectral and spatial data. For remote sensing missions such as crop disease or invasive species detection, the spectral range of most interest is the visible-near-infrared (VNIR) from 400-1000nm.

Geologic exploration requires a different spectral region as spectral signatures of interest are evident in the shortwave-infrared (SWIR) range of 900-2500nm. Each type of mineral has its own unique spectral signature reflecting its chemical composition. Since certain minerals reflect light slightly differently, it's important to have many contiguous spectral bands.  

Given the sensor requirements for generating SWIR hyperspectral data, spectral imaging sensor systems require efficient consideration of size, weight, and power requirements for deployment on UAVs. Headwall has worked strategically to 'lightweight' its Hyperspec sensors for field deployment. One of the main design aspects is that Headwall uses an 'all-reflective' approach which allows for a very small instrument size and form factor. The Hyperspec sensors are smaller and lighter but also more robust in airborne situations, particularly for UAV deployment. 

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Headwall's Micro-Hyperspec SWIR is being successfully deployed on the multi-rotor UAVs with excellent stability and imaging results. What's more, the entire payload also includes a high-performance GPS/IMU and Headwall's HyperCore data-fusion hub that synthesizes the data streams coming from complementary instruments. For example, LiDAR can also be integrated to the payload and handled by HyperCore.  

There are several aspects of Headwall’s spectral imaging sensor design that are advantageous for geological research. “When you’re using a UAV, flight time is crucial,” said Peter Clemens, Director of Engineering at Headwall. “Efficiently capturing wide swaths of valuable image data on each flight is therefore a huge advantage.” Headwall has built ortho-rectification into its Hyperspec spectral software allowing users to generate highly accurate geospatial data. “We give our customers the technology to identify not only what they see within the scene but a precise location as to where it is on the ground,” continued Clemens. Headwall has developed solution bundles that package both hardware and software systems necessary so that customers can quickly acquire spectral data but also efficiently process this data and view spectral maps.

Tags: hyperspectral imaging, Airborne, Remote Sensing, geology

The Eyes Have It...But Not Always

Posted by Christopher Van Veen on Thu, Apr 13, 2017

Humans have a marvelous ability to see and identify objects within what is called the visible range of the electromagnetic spectrum. That starts at roughly 380 nanometers and goes up to around 700 nanometers or so.

But there are things that researchers and scientists might wish to 'see' that fall below (ultraviolet) or above (infrared) this 'visible' portion of the spectrum. If you were a bumblebee, you could see into the UV range; a rattlesnake, you could see into the infrared range. Obviously (and thankfully) we're neither, but to see into these other ranges we need help. And why would we care about anything our eyes cannot see? Well, to take just precision agriculture as a key example, there are vegetative indices (VI's) that depend on seeing into the infrared ranges where the spectral signatures of chlorophyll fluorescence are detectable. Chlorophyll fluorescence is predictive of crop stress and vigor, so being able to see and quantify its effects can tell crop scientists much more than their own eyes can. 

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Since we aren't bumblebees or snakes, we need tools to see into the nether regions of the spectral range. Hyperspectral and multispectral sensors do the work our eyes can't, and they do it very well. They collect, in the case of hyperspectral, a full spectrum of image data for every pixel within the field of view. Dozens of vegetative indices exist, with each using spectral data to discern answers to questions: Are there diseases on my crops I cannot see? Is my soil nutrient-rich? Are there invasive species I need to worry about? In the end, scientists concern themselves with finding answers to these and other questions rather than poring over complicated hyperspectral data cubes. In layman terms, you go to Home Depot not to buy a drill; you go there to buy a hole.

Hyperspectral and multispectral differ with respect to the amount of image data being collected. Hyperspectral is to multispectral what hundreds of bands are to a handful. With multispectral, you also may have gaps between the rather wide bands and what you want to detect with the sensor might not register. But hyperspectral represents hundreds of narrow and contiguous spectral bands, so if a certain spectral signature is there you'll see it. There are places for both multispectral and hyperspectral; if you know the spectral signature of the vegetative indices of interest and you're sure the multispectral sensor can capture it, you're all set. But much more common is the case where scientists do not exactly know where along the electromagnetic spectrum a key VI exists. Is it somewhere between 400 and 1000 nanometers (nm), which we call the visible-near-infrared VNIR range? Or is it in further up, between 900-2500nm (the shortwave-infrared SWIR range)? Indeed, missions may change over the course of the instrument's life, which means that scientists would opt for a combined VNIR-SWIR sensor capturing image data from 400 nm all the way up to 2500 nm.

Hyperspectral and multispectral imaging sensors are often 'line-scan' instruments, basically meaning they capture image data a slice at a time. The composition of all these slices (or frames) is a hyperspectral data cube, which can be several gigabytes in size. Post-processing software is very good at unscrambling this complex cube of data into meaningful answers, but just as important is aircraft stability. Since UAVs are quickly becoming the 'go-to' platform for crop scientists and others, making sure the craft is stable in the air is fundamental to making sure the data is orthorectified. In other words, not a casualty of a wobbling UAV. Fortunately, stabilized gimbals are outstanding nowadays, having the immediate ability to keep the sensor in its desired position no matter what the craft does.

Obviously, a UAV-based remote sensing system is a function of optics, electrics, and aerodynamics. Integration is an overlooked task, because many users assume that they can buy a UAV and a sensor and bolt the two together. Unfortunately, experience shows that such a piecemeal a-la-carte endeavor is likely to fail. Battery life comes into play, balance rears its head, and understanding the relationship between frame rate and ground speed can flummox anyone. Fortunately, though, companies like Headwall Photonics exist to manage this integration process. They understand a thing or two because they've seen a thing or two. They can recommend the right kind of UAV, take size/weight/power (SWaP) into consideration, integrate spectral sensors with other instruments such as LiDAR, and deliver turnkey, flight-ready packages that even bumblebees and snakes would have to admire. 

Tags: hyperspectral imaging, Airborne, Remote Sensing, Nano-Hyperspec

A Hyperspectral View of Western Australia's Ningaloo Reef

Posted by Christopher Van Veen on Wed, Feb 15, 2017

Headwall's hyperspectral imaging sensors are used around the globe for a wide variety of remote sensing missions. Hyperspectral sensors can see well beyond the limits of human vision, which runs to about 700 nanometers (nm). Many of the scientific research projects demand the ability to see into the infrared ranges, often up to and beyond 2500nm.

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What can you see beyond the limits of human vision? Most importantly, the early signs of stress and disease on plants and vegetation becomes visible with enough time to mitigate the problem. Crops can be saved, which itself holds enormous financial benefit to industry and regional economies. Scientific learning about geological deposits and climatology is also improved through the use of hyperspectral imaging in the infrared ranges. The sensors can collect literally hundreds of spectral bands per pixel, meaning the amount of useful data is enormous. The telltale sign of a disease condition on a crop tree would be missed by human vision but is easily seen through the lens of a hyperspectral sensor. That's because light reflects differently based on the chemical composition of a diseased leaf versus a non-diseased one.

In Australia, Headwall's hyperspectral sensors are hard at work examining the Ningaloo Reef. The small size and weight of the Hyperspec® sensor allows them to be carried aboard today's newer multi-rotor and fixed-wing UAVs. The UAV is a preferred platform for mounting scientific sensing instruments because they are more affordable and tactically efficient for these kinds of missions.

The overall health of the reef coral can be seen with a tremendous amount of clarity, allowing scientists to spot unwanted environmental trends long before they become a problem.

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Spreading Holiday Cheer at Headwall

Posted by Christopher Van Veen on Wed, Dec 21, 2016

In 2016 Headwall embarked on a mission of volunteerism. The small, 50-person technology company headquartered in Fitchburg understood that the community it called home was also home to disadvantaged families in need. So beginning with a variety of projects throughout the area, Headwall employees embraced the opportunity to ‘give back’ by partnering with a local charitable organization called Our Father’s House.

“Our goals were twofold,” said Robin Jacobs of Headwall. “We wanted to help out wherever the need arose and we wanted to have broad employee participation,” she said. In addition to sprucing up neighborhoods and planting trees, Headwall and its employees purchased and assembled hundreds of ‘personal care kits’ for disadvantaged people in the area. “It really was a fun experience each time we assembled these kits,” said Robin. “We all knew we were putting a smile on someone’s face and making their difficult life a little less difficult.”

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Headwall had almost 100% employee participation in purchasing new gifts for area children. 

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Headwall employees carrying gift bags to Our Father’s House transport truck

Just before Thanksgiving, Headwall assembled all the makings for complete feasts to be distributed to area families through Our Father’s House. “We thought of everything,” said Robin. “Right down to the cooking pan for the turkey!” The partnership with Our Father’s House works well because they handle the distribution and organizational logistics to make sure that everything that Headwall donates fills a need.

Right after Thanksgiving, Our Father’s House pulled together a list of 41 children living at the Devens Transitional Center. These children, some as young as two, were in desperate need of new winter clothing such as hats, coats, and mittens. Almost immediately all 41 children had been spoken for, with gift bags containing brand-new outfits crowding the Headwall lobby. “We really captured the spirit once again,” said Robin. “Taking care of 41 children across a company our size meant we had just about full employee participation.”

Seeing a smile on the face of each child as they unwrap their gift is a very rewarding experience. “Many of these kids have never been given brand-new gifts before, and it was fun for each employee to pick a name off the tree here at Headwall and know that we were making that child happy.”

 

Tags: Fitchburg, Our Father's House, Charity, Giving, Christmas

The Spirit of Giving at Headwall

Posted by Christopher Van Veen on Fri, Nov 18, 2016

The corporate environment is always a bustling one: Getting and shipping orders, building sensors, designing new products, and maneuvering through a seemingly endless stream of meetings. But at Headwall, we take the opportunity to ‘give back’ to several central Massachusetts communities with families in need. This can range from assembling ‘personal care kits’ to cleaning and beautifying neighborhoods. This happens several times during the year, and is a part of Headwall's ongoing pledge to donate and contribute wherever possible to those less fortunate.

Today, Headwall employees gathered all the fixings for full Thanksgiving dinners to be distributed to dozens of area families during the upcoming week. This was done in coordination with ‘Our Father’s House, Inc. of Fitchburg, Massachusetts, which is a nonprofit focused on assisting the homeless in Northern Worcester County. Everything from the turkey and stuffing right down to the baking pan was included and boxed, before being carefully loaded aboard a truck at Headwall’s facility.

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“This is something we take a tremendous amount of pride in doing,” said Robin Jacobs of Headwall. “We have partnered with Our Father’s House consistently and we know our help and assistance is so appreciated.” In addition to the turkey dinners and personal accessory kits, Headwall had a company ‘coat drive’ so that as many homeless people as possible could have warm outerwear before the winter chill sets in. "Our entire employee base rallies around these projects whenever they arise," said Robin. "It's a collective sense of joy to be involved with charitable work like this, and our relationship with Our Father's House is a very rewarding one."

“I can’t express enough how grateful we are to Headwall for their continued assistance,” said Kevin MacLean, Director of Homeless Services at Our Father’s House. His organization has evolved into much more than just a shelter for the homeless and now offers comprehensive case management. Our Father's House works with other local agencies to make sure that the needs of the homeless are dealt with proactively rather than reactively. “That’s why our partnership with Headwall is so valued,” said Kevin. “There are families and individuals who will now have a nourishing meal on Thanksgiving and warm coats for the winter.” 

Tags: Fitchburg, Our Father's House, Charity, Giving, Thanksgiving

Almond Inspection Goes High-Tech

Posted by Christopher Van Veen on Fri, Nov 18, 2016

In Manteca, CA about 90 minutes south of Sacramento sits Travaille and Phippen, a family-run business focused on processing the world's finest almonds. Manteca sits at the heart of California's agricultural valley, which is ripe with growers and processing companies of everything from avocados to nuts. Chances are, the produce that you pick up at your local grocery store comes from this fertile part of California that stretches hundreds of miles from north to south.

Almonds are increasingly America's favorite variety of nut, with consumption rate increases that are far surpassing those of even peanuts. And this preference is not limited to America; most other parts of the world share this craze for almonds. Indeed, the acknowledged health properties of almonds make them a favorite, guilt-free snack.

Sitting between growing and eating almonds sits an important phase of the operation: Processing and inspection. At Travaille and Phippen, there is a recognition that diligent inspection protocols can result in a rapid payback: Consumers see a higher-quality product and government regulators appreciate their proactive approach to quality and safety. Scott Phippen is CEO of Travaille and Phippen, and he has made this connection while many of his competitors have not. "Our success comes from delivering pristine quality almonds globally," he said. "Whether it's Japan, the Middle East, or here in America, there are differing preferences for what consumers like to see. But what doesn't differ is a need for highest quality."

 

 

One of the approaches Phippen embraced was to adopt spectral imaging technology near the end of the inspection process. The normal 'upstream' processes are designed to take out foreign material such as twigs, rocks and bits of shell. As 'good' product moves through to the final inspection stages, spectral imaging takes over to deliver a more granular look at the almonds. "Coloration is a huge grading factor," said Phippen. "You can have two or three really good-looking almonds in your inspection stream, with each having a slightly different tone or color. Spectral imaging allows us to segregate these 'good but different' almonds better than we ever could."

Getting Travaille and Phippen to this stage was a classic exercise in integration between Headwall and Bratney Companies (Des Moines, IA). Bratney provided several fully integrated inspection lines that featured conveyors, sensors, vacuum robots, and software control that allowed Travaille and Phippen to significantly boost its inspection quality while using 60% fewer people. For Peter Bratney, CEO of Bratney Companies, the overall marriage between varying but complimentary technologies is paying dividends. "Travaille and Phippen is just one example of our integration expertise delivering a demonstrable return on investment," said Peter. "Headwall's hyperspectral imaging sensors can 'see' with a resolution and clarity that allows any food processing company to grade or distinguish its product better than ever."

As almonds enter the final inspection stream, small hyperspectral sensors silently scan from above. The sensors are armed with spectral libraries (basically algorithms) that represent 'instruction sets' for the downstream robotic arms a few feet down the line. Almonds that match a pre-determined spectral signature are allowed to pass while ones that don't are vacuumed away. These might be cracked almonds, or even bits of foreign material not captured during earlier inspection phases. But color uniformity is important in the almond business, and the Bratney solution allows Travaille and Phippen to distinguish between almonds with miniscule coloration differences. “This is where advanced machine vision is headed,” said Bratney. “The key is in identifying cutting-edge technologies and then integrating them for the common good.”

The food-processing industry understands imaging technology to a degree. RGB (red, green, blue) cameras are familiar. But today, with product quality and safety on everyone's mind, a finer net is needed. The push toward 'Advanced Machine Vision' is gathering momentum as food processing companies recognize that new types of spectral imaging technologies are needed. "Travaille and Phippen is capturing attention in the competitive global almond market because of their proactive approach to technology,” said Bratney. “This allows them to deliver a level of quality that’s hard for others to match.” 

Tags: hyperspectral, Almonds, almond inspection, Manteca, CA, Travaille and Phippen, Bratney Companies, advanced machine vision

Nano-Hyperspec, PrecisionHawk Impress!

Posted by Christopher Van Veen on Wed, Jul 06, 2016

Steven Sexton is Technical Consultant at Aerial Imaging Services, LLC (Ephrata, WA). With broad availability of new UAVs and high-performance hyperspectral imaging sensors, Steven's business is a good one. 'Remote sensing' is the study of agriculture, climatology, geology, and infrastructure from airborne platforms. The amount and quality of image data the sensors collect is amazing, allowing scientists to make important decisions about crops, plant health, mineral deposits, and environmental trends.

Recently, Steven teamed up with Precision Hawk (Raleigh, NC) and Headwall Photonics to put one of these 'flying laboratories' into the air. Because the combination of UAVs and specialized sensing instruments is still 'new' to many users, ease of integration and great customer support from Precision Hawk and Headwall allowed Steven to get into the air collecting data-rich images of the ground below. Precision Hawk took care of many of the airborne issues while Headwall addressed the hyperspectral side of the application. Together, both companies helped Aerial Imaging Services reach a very impressive level of differentiation in a still-emerging business. The myriad of mechanical, electrical, optical, and aerodynamic considerations can be daunting, and Steven took to LinkedIn on June 28, 2016 to tell his story:

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I am going to shift focus to sensors today. I recently acquired a Nano-Hyperspec Sensor from Headwall Photonics and PrecisionHawk. This sensor is absolutely amazing, and is configured to just plug right onto the Lancaster Rev 4 and the Lancaster 5. This Plug and Play setup is how all of the sensors PrecisionHawk sells. Making it extremely easy to do a visual scan, land, change to a  BGNIR sensor and fly. They sensors scan at much higher resolutions then most multispectral sensors. Around here being at a higher altitude means not running into the trees lining fields, silos, buildings etc. I get 1.5cm per pixel at 100m or 329 feet AGL. I go lower for Lidar and thermal to 60m or 196 feet AGL.

Now this may seem a little high but with the higher resolution sensors I got from PrecisionHawk, it just made sense, less worry and more time to just watch the Lancaster do its thing. It also means I don't have to make as many passes over a field like I would at lower altitudes. Now I haven't heard anyone say the resolution of some of the newer multispectral sensors that recently have come out or those that I may not know of. If you use one of these, and it gets as high of resolution, please, either leave a comment and share your results or message me so I can add that information to this article. I want to give everyone a fair shake here.

steve_sexton.jpgNow back to the Headwall Photonics Nano-Hyperspec® sensor. This unit is a little heavier than most of my other sensors, The LiDaR is about as heavy. The reason for the extra weight is a 500gb SSD drive attached to it. It also has a network cable interface to hook to your computer or laptop. Please read the manuals that come with it, it will save you a lot of headaches trying to figure out how to access the SSD on the sensor. You can find general information at the Headwall site here.

The customer service from Headwall is absolutely amazing. I decided to update the Nano driver software and missed one step and wound up not being able to access the data. Now this was totally my fault, I kind of went in blind to do the update.

Greg Chenevert from Headwall was extremely helpful and had me try a few things. These didn't work, but Greg spent time trying to help me get things going and guaranteed that they would get it back up. He put me in contact with one of the companies programmers, I gave him remote access to my system with the Nano hooked up and running and he had it all set up, reconfigured and doing imaging within probably 15 minutes at the most. Now I don't know about the rest of you, but most companies don't even come close to the customer service of Headwall and PrecisionHawk. They went way above and beyond to get the sensor working so I could do my job.

The unit itself is not that big, it is the bracket and connectors for the plug and play that make it seem larger. On average I can swap out a sensor and battery in about 30 to 45 seconds. The battery only lasts for about 35 minutes with the heavier load, but I get some pretty amazing images with it.

Headwall has software that accompanies the sensor that are very useful and allow you to transfer the files to a local drive on your computer or laptop. You could even transfer it to a USB drive if you have one that can hold the amount of data you get. There is also an option to view the data in NDVI, now this can be done in the field if you so desire. I usually just bring it back to the office and process it there and add it to other data sets I have gathered on that particular job. It does make the farmer happier if you can show it in the field.

Lancaster.jpgWhen I first started I was unsure of which sensors I should purchase. I imagine several of you have or had the same issue. I determined that if I only get the sensors for agriculture then I am going to be very poor during the winter months. I decided to add the LiDaR, thermal, and the HeadWall Nano-Hyperspectral sensor. This gives me the ability to do other types of work during the non growing season. I also don't mind travelling to a location or even going to another area for several weeks at a time so this also opened up income opportunities.

The data is only as good as your sensors are. Sure the higher quality imagery costs a bit more, but, it also means the data is going to be more precise. Combined with the DataMapper Algorithms you get a very complete package from one source.  

Tags: Remote Sensing, UAV, precision agriculture, Nano-Hyperspec, PrecisionHawk

Hyperspectral Imaging & Processing Takes Hold in Turkey

Posted by Kevin Lynch on Mon, Jun 06, 2016

Hyperspectral imaging is a very valuable scientific technique for a wide range of applications that extend far beyond the defence and military uses the technology was originally conceived for. These include airborne precision agriculture, advanced machine vision, forensics, medical science, cultural preservation, and a range of others. For scientists in these application areas, hyperspectral imaging is often a new tool where the need for education is quite common. As a leader in the field of hyperspectral imaging, Headwall partners with its international resellers to sponsor workshops and events that are geared toward promoting an understanding of hyperspectral imaging and how best to use the rich data coming from the sensors.

Headwall and its valued partner in Turkey (Visratek) recently sponsored a "Workshop on Image and signal Processing" organized by IEEE GRSS Turkey Chapter under the "24th Signal Processing and Communications Applications" (the abbreviated Turkish name is SIU).  Held annually since 1993, SIU has organized in various cities throughout Turkey. In 2016, the location was in Zonguldak, sponsored by Bulent Ecevit University. The events are very well attended with the 2015 SIU attracting more than 700 submitted scientific papers written in Turkish with an abstract in English. A technical program committee of more than 600 experts provided more than 1,500 paper reviews. Attendence is roughly 600 leading scientists, researchers, and industry practitioners from Turkey. Says Visratek head Fatih Ömrüuzun, "This is the event where visibility is very important; our linkage with Headwall and our sporsorship of SIU puts us in a very good position as expert in this field."

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The IEEE SIU Conference is therefore the most significant scientific event of the signal processing and communications community in Turkey. The conference is four-day event. The first three days are dedicated to keynote talks from distinguished lecturers from worldwide universities. Also, tutorials and technical sessions include oral or poster presentations of scientific papers. 24th IEEE SIU conference also featured an industry forum and exhibition program where Headwall and Visratek were prominent. The fourth day of the conference was dedicated to the social programs including day trips to beautiful and historical towns such as Amasra, Safranbolu and Kdz. Ereğli) at the coast of the West Black Sea Region in Turkey.

Tags: hyperspectral, signal processing, Visratek, IEEE, Turkey

Community Partnership in Action!

Posted by David Bannon on Thu, Apr 28, 2016

Great companies can serve not only as an economic engine for customers, employees, suppliers, and business partners but also as a strong community partner based on how that company integrates itself into the communities in which it operates.

So many times, employees follow the same morning routines to get to work – a cup of coffee on the go, a 25 minute commute to work, pull into the parking lot, and do your thing every day. But picking your head up and looking at the community and the surrounding neighborhood as you go to work every day reveals a lot and helps to define where we can have a positive social impact as a company and as an individual.   This perspective helps us to understand our community’s strengths, resources, cultural diversity, as well as a heightened awareness of community need.

community_partnership.jpgA cornerstone of strong, thriving companies is to establish a brand as a good community partner; defining a commitment to social responsibility and community philanthropy needs to be more engrained in the cultural fabric and strategies of companies.

As an element of our FY16 success plan, Headwall has undertaken a new community service initiative with our employees. A group of employees conducted site visits to a number of community service organizations. As a result, Headwall is working to support Our Father’s House, a local non-profit organization based in Fitchburg that is providing shelter and transitional services to homeless men, women, and children in the community.

VOLUNTEER_PROJECT.jpgAdditionally, a group of five volunteers from Headwall went to a work project for Growing Places, a local organization that runs community gardens and teaches gardening classes to residents of Fitchburg and Leominster. The group met at the Growing Places warehouse in Leominster, where the first project involved power-washing three tanks to be used for storing water at the community gardens. One tank had been full of black dye, another contained glue, and a third one held corn syrup. 

Everyone involved got stained with the black dye, and were ultimately unsuccessful in cleaning that tank. In the end, two tanks were cleaned and delivered to the Sundial Community Garden, and the Cleghorn Community Garden, both in Fitchburg. You can read more about the projects here.

The work was challenging, but much of the danger was mitigated by putting the most dangerous engineer in a cage. The two cleansed tanks were loaded into a truck and delivered to the community gardens. The first garden was surrounded by a fence that the volunteers had to lift the tank over. After both tanks had been installed at the community gardens, the group moved on to a third site, adjacent to the Cleghorn Garden, to plant two large apple trees that had wintered over but were lying on their sides.

The trees were removed from the shallow holes in which they had spent the winter, the burlap and wire baskets were removed from the root balls, and two large holes were dug. A full group effort, led by Kevin Didona, successfully placed the trees upright in their new homes. The dirt was replaced, and the community now has two lovely apple trees.

The staff at Growing Places was very pleased with all we were able to accomplish, and there will be opportunities for more cooperation between that group and Headwall Photonics in the future. We have discussed the possibility of a project at the Headwall facility where volunteers can build frames for raised beds at the community gardens.

 

Tags: Fitchburg, community partnership, Volunteering, employee activities

Landmine Detection Using Hyperspectral Imaging

Posted by Christopher Van Veen on Wed, Apr 20, 2016

 

 

When you see how rapidly the use of drones for scientific research has risen, you first conclude that it's all about precision agriculture and climatology. To be sure, those are trendsetting applications when it comes to using hyperspectral imaging sensors aboard UAVs. But over at the University of Bristol, two scientists are leading a team focused on 'finding a better way' to detect the presence of landmines that kill or maim thousands of people annually. With around 100 million landmines underneath the ground globally, traditional means of finding and eliminating them would take about 1,000 years and cost upwards of $30 billion according to some estimates.

Find A Better Way is a UK-based NFP founded by famed footballer Sir Bobby Charlton. Despite his heroic sporting achievements, Sir Bobby is now forging a legacy outside of football through his determination to champion the cause of landmine detection and elimination. He witnessed the destruction caused by landmines on visits to Cambodia and Bosnia as a Laureus Sport for Good Ambassador. He founded Find A Better Way after recognizing that research and development held the key to making the major changes necessary to allow humanitarian teams to rid the world of the threat of landmines.

"We want to do something that very quickly delivers a step-change in capability while reducing overall human risk involved with finding and eliminating landmines," said Dr. Tom Scott of the University of Bristol. He along with Dr. John Day are pairing their advanced UAV with small and lightweight hyperspectral imaging sensors from Headwall Photonics to 'see' with a specificity and resolution unheard of only a few short years ago. "These drones can be autonomously deployed to fly over a landmine area and provide high-resolution images that allow us to reconstruct the 3-D terrain with very high accuracy," said Dr. Scott. With all the landmines across the world, tactical deployment of numerous low-flying drones is going to win the day over expensive satellites or high-flying aircraft. In order to meet this objective, the package needs to be simultaneously affordable, light, and suited to its mission. There is a vast amount of integration and testing work involved before the first meaningful flights can be flown. Recognizing this, Headwall is assuming much of this work so that users can compress this time-to-deployment significantly. Because the use of drones for scientific research is still in its infancy, misconceptions abound. Acquiring a UAV and slapping a hyperspectral sensor to it without first considering all the variables is a recipe for disaster. This holds true whether the mission is landmine detection or precision agriculture. More commonly, other instruments such as LiDAR and GPS are part of the payload as well. The end result is a carefully balanced exercise in aerodynamics, optics, electrics, and data-collection that companies such as Headwall are able to manage.

The human eye can only respond to wavelengths between roughly 390-700nm. Many of the reflective 'signatures' given off by plants and chemicals fall outside that range. For example, the Nano-Hyperspec sensor used by the Bristol team operates in what is called the 'Visible-Near-Infrared' range of 400-1000nm (called 'VNIR' for short). In that range, the sensor is 'seeing' with an extraordinarily high degree of specificity and resolution and far beyond what a human could discern. Indeed, these sensors are collecting an astounding amount of spectral data on a per-pixel basis, resulting in 'data cubes' many Gigabytes in size. Armed with spectral libraries that faithfully characterize the specifics of the terrain below, scientists can match the known library information with the collected airborne data and make quite accurate calls on what's what.

The use of drones has accelerated this scientific effort because of two factors: First, they are affordable and easy to deploy on a tactical basis. One can be packed in a Range Rover and deployed almost anywhere in minutes whereas aircraft and satellites are, by nature, constricted, inflexible, and costly. This is not to say that aircraft and satellites will be supplanted by UAVs. There is valuable image data that can be collected using these high-flying platforms, and the overall knowledge base shared by the scientific community is made much more complete when all these assets are used in a synergistic fashion. Indeed, hyperspectral imaging was once the province of high-flying reconnaissance planes and satellites...neither of which could ever be used economically by university scientists. But the ubiquitous drone--a bane to some and a blessing to others--is the perfect platform from which to launch these exploratory efforts. "We're adding a bit more science to the UAV payload now," says Dr. Day. "We're starting to look at the spectrum of light and the colors of light that are coming off the minefield and using that data to find where the landmines are."

UAVs and drones seem to get media attention for all the wrong reasons, which is exactly why efforts by the esteemed team at the University of Bristol are to be applauded for developing a 'Better Way' to solve some of our toughest challenges. Hyperspectral imaging sensors can 'see' even beyond the VNIR range of interest to Dr. Day and Dr. Scott. The Shortwave-Infrared (SWIR) range starts near where VNIR leaves off, covering around 950-2500nm. The presence of certain chemicals, minerals and of course plant photosynthesis will become visible to sensors like these. Indeed, a broadband sensor package that covers the VNIR and SWIR range (400-2500nm) is particularly useful because it basically collects everything a scientific research effort might wish to see.

There are two key factors about hyperspectral imaging that are worth noting. The first is that the technology depends on 'reflected light.' The sensor is basically looking at how sunlight reflects off certain materials. Plant fluorescence, for example, has a particular 'spectral signature' that a sensor can understand. Obviously, this means an airborne hyperspectral sensor depends on a healthy amount of solar illumination and certainly is useless at night. But Headwall's sensors are designed to collect precise image data even under less-than-ideal solar conditions (cloud cover, or low angles, for example). The second factor is having a wide field of view. The sensor obviously can 'see' directly beneath the line of flight, but being able to do so off to the wide edges of the flight pattern makes the mission more efficient. Batteries being what they are, optimizing the flight duration by capturing a wide swath of land is obviously beneficial. This benefit is seen in the precise optical layout used by Headwall in the construction of each sensor.

Crop science, climatology, geology, and even the inspection of infrastructure such as pipelines and rail bed depend on imaging sensors like those produced by Headwall. Hyperspectral sensors depend on 'motion,' since they basically collect images slice by slice as the UAV flies over the scene. The combination of all of these high-resolution 'slices' comprise what is known as a 'data cube,' which is pored over by scientists during post-processing. Of course, the hardware capturing these images represents about half the story. The other half can be found in the software that makes sense out of reams of spectral image data that all needs to be 'geo-tagged' and orthorectified. First and foremost, scientists need answers; the data (and the sensor collecting the data) are simply means to an end. When you go to your local DIY or Lowe's or Home Depot, you really aren't buying a drill; you're going there to buy a hole.

But is all that image data really needed? Some efforts seek to cut corners by using less-capable 'multispectral' sensors that cover only a few bands rather than the hundreds of bands covered with hyperspectral. Using crop science as an example, a multispectral sensor might miss the telltale signature of an invasive disease on a tree canopy while hyperspectral will most certainly catch it. And that can mean the difference between saving a coffee bean harvest or a valuable wine-vineyard crop.


 

Tags: hyperspectral, Remote Sensing, UAS, UAV, University of Bristol