Headwall Photonics Blog

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

Smaller, Lighter, Better: Hyperspectral on UAVs

Posted by Christopher Van Veen on Fri, Aug 08, 2014

At Headwall we've been busy listening to the market. When it comes to airborne remote sensing, the market is telling us that they favor UAVs (unmanned aerial vehicles) of all kinds: fixed-wing, multi-rotor, and so on. There's no end to the number of companies producing UAVs globally. Because many UAVs produced today are very small and affordable they are 'within reach' of those with even modest means. Universities represent one key market where the use of UAVs is rapidly increasing. Full of scientists and research departments, universities around the globe see these small and light UAVs as a perfect platform from which to launch their exploratory studies. They are affordable, easy to assembly and transport, and (especially with multi-rotor models) can take off and land within a very small footprint.

UAV with NanoBut alongside all this enthusiasm for UAVs, there are many who frown upon these airborne vehicles and see them as a nuisance. Indeed, they can be a nuisance when used for trivial pursuits. In densely-populated areas they certainly can be more than an annoyance...they can be dangerous. But largely, the work we are seeing our customers undertake with hyperspectral imagers attached to UAVs is very valuable work indeed. And it takes place far from the hustle and bustle of any urban landscape. For example, precision agriculture is made more valuable because there are key indices to plant health and physiology that are readily seen from above than from below. Certain disease conditions are ‘visible’ using hyperspectral imaging, especially with high spectral and spatial resolution found on all Headwall sensors.  Other research pursuits include environmental analysis, geology, pollution analysis, and so many more. These are very good and valuable scientific efforts made moreso by the UAVs that enable these precision instruments to 'fly.' The marriage between hyperspectral and UAV seems to be a perfect one, especially when you consider how much ground can be covered with one of these flying wizards. And especially when you realize that hyperspectral imaging fundamentally requires that movement needs to occur. In other words, hyperspectral was meant for airborne deployment. Where a Jeep can’t go, a UAV can. And furthermore, more ground can be covered with a UAV, meaning more efficient data collection over rugged and inaccessible landscapes.

Nano-HyperspecAs UAVs get smaller and lighter, users run headlong into the issue of payload: UAVs are limited with respect to what they can lift. Whatever else a UAV is asked to carry, it needs to lift batteries. Then comes the instrumentation. Headwall’s Nano-Hyperspec was just introduced for the VNIR (400-1000nm) spectral range. Most (but not all) of the things a research scientist might wish to ‘see’ are visible in this spectral range. But we did a couple things with Nano-Hyperspec that helps the payload issue. First, the size and weight are well below previous sensor offerings. Its size (including lens) is a scant 3” x 3” x 4.72” (76.2mm x 76.2mm x 119.2mm), and its weight is less that 1.5 lb. (0.68kg). Best of all, this includes on-board data storage of 480GB. That’s about 130 minutes at 100fps.

Aside from making Nano-Hyperspec smaller and lighter than other hyperspectral sensors, a key differentiator comes from embedding the data storage within the enclosure while providing multiple attach points for the GPS/INU. Another key attribute is the inclusion of the full airborne version of Headwall’s Hyperspec III software, which includes a polygon flight tool for sensor operation and a real-time Ethernet Waterfall display. While the work to shrink the size and weight of Nano-Hyperspec is valuable by itself, it does allow the user more room and available payload to carry other instrumentation. Hyperspectral combined with LiDAR and thermal imaging is an extremely valuable package that is made possible thanks to the overall size/weight reduction of Nano-Hyperspec and the embedding of the data storage/management capabilities (which were contained within a separate enclosure previously).

Hyperspec III software gives users full control over data acquisition, sensor operation, and datacube creation in ENVI-compatible format. Hyperspec III also works in full conjunction with the GPS that can be paired with the sensor as an available Airborne Package. In this optional package, customers are able to take advantage of real-time computation of inertial enhanced position/velocity, ~161dBm tracking sensitivity, accurate 360-degree #D orientation output of attitude and heading, correlation of image data to GPS data, and much more. During post-processing, the Airborne Package also effortlessly handles radiometric calibration and conversion as well as orthorectification.

 

 


Tags: Airborne, Remote Sensing, UAV, agriculture, precision agriculture

UAVs and Hyperspectral Imaging Unite

Posted by Christopher Van Veen on Tue, Mar 25, 2014

One of the things we’re seeing at Headwall is the proliferation of airborne applications. Multispectral suffers a bit with respect to hyperspectral (a handful of bands versus hundreds), which is why hyperspectral is winning the day.

UAV choicesOne reason is instrument affordability. Multi-million-dollar hyperspectral sensor programs might have flown (literally and figuratively) in the military world, but not in precision agriculture or with universities. Budgets are smaller, and that money has to be spread among not only the sensor but the UAV and everything in between. This is where small, entrepreneurial companies like Headwall shine, because everything in between can mean LiDAR, GPS/IMU technology, application software, data processing, and so much more. We understand hyperspectral imaging better than anyone, and our focus has always been to better that technology while driving costs lower. This is the essence of commercial-off-the-shelf (COTS), where highly specialized military instrumentation finds a home all across industry and academia. With respect to Headwall, COTS implementation means smaller, lighter and more affordable sensors that are easier to use yet just as optically precise as their multimillion-dollar military counterparts.

Second, you cannot go a day without seeing stories about UAVs. Fixed-wing designs like those from AGX and PrecisionHawk are crowding the skies along with multi-rotor helicopters like Infinite JIB and AIBOTIX. These are much more than hobbyist playthings and are perfect for scientific reasearch duties. They have excellent range and payload-carrying characteristics, and they are stable aloft.  From mineral exploration and agriculture to petroleum and pollution control, UAVs are everywhere it seems. And everyone takes notice when household names like Facebook, Google and Amazon decide that the UAV is going to be instrumental to their future success. Much of this might sound fanciful and far-off, but it is happening now. Court challenges are being won, and while care needs to be taken on how regulations are drafted and enforced, no one doubts that the UAV is not only here to stay but will become commonplace.

Obviously, UAVs simply take up airspace unless they are doing good work. And largely, we seem to hear about bad things happening when mention of UAVs (and drones) is made. But stop and consider for a moment how a famine-stricken area can be made crop-fertile thanks to hyperspectral data that a UAV-mounted sensor can collect. A scientist will know about disease conditions with enough time to prevent damage by skimming the treetops and looking for anomalies that become ‘visible’ through hyperspectral imaging. A farmer will know where to plant and harvest…and where not to. Crop stress will be seen long before it becomes a worry, and the amount of wholesome and nourishing food planted in areas once thought impossible will blossom. In short, small and light UAVs are affordable for the people who need to use them. They can be flown in areas that vehicles and humans cannot yet reach, providing a window of research never available to scientists before.

As we see the proliferation of UAVs capable of carrying sensor payloads, it is important to understand how everything goes together. Here, Headwall is taking a leading role. Many mistakenly believe that slapping a sensor onto an octo-copter is all they need to do. But making sure everything works the way it should aboard a flying, unmanned vehicle is another challenge altogether. How much ground do you need to cover, and do you have enough battery power to do it? How much hyperspectral data do you need to collect, and do you have the computing and storage horsepower to make that happen? What are you looking for, and what spectral ranges are those things in? How do you ortho-rectify the data during post-processing? And how do you use the science of ground-truth as it relates to airborne hyperspectral imaging? This last consideration is hugely important, because the collaboration of airborne hyperspectral and ground-truth delivers the best possible accumulation of data. Headwall and ASD have even authored a 12-page whitepaper on the relationship between airborne hyperspectral data and ground-truth techniques.

Tags: hyperspectral imaging, Airborne, Remote Sensing, UAV, precision agriculture

Hyperspectral Sensors for UAV Applications

Posted by Christopher Van Veen on Wed, Feb 19, 2014

The scientific research community is beginning to understand and embrace hyperspectral imaging as a useful tool for a few primary reasons. First, sensors are more affordable than ever. Originally conceived as multi-million-dollar ISR platforms for defense applications, hyperspectral imagers have been successfully ‘commercialized’ over the past few years. Scientists typically embracing RGB or multispectral technology before can now acquire hyperspectral sensors at affordable price points.

Hyperspectral sensors of the ‘pushbroom’ type produced by Headwall require motion to occur. That is, either the sensor flies above the field of view, or the field of view moves beneath the sensor. For UAV applications, Headwall’s small and lightweight Micro-Hyperspec is the platform of choice. Available in the VNIR (380-1000nm), NIR (900-1700nm), and SWIR (950-2500nm) spectral ranges, the sensor is truly ‘SWaP-friendly.’

Spectral range is often where the decision-making starts. The chemical fingerprint—or spectral signature—of anything within the field of view will lead the user in one direction or another. For example, a certain disease condition on a tree canopy may become ‘visible’ within the SWIR spectral range (950-2500nm). Similarly, a certain mineral deposit may become ‘visible’ in the VNIR range (380-1000nm). One approach to ensuring the spectral ‘fidelity’ of images collected by the sensor makes use of ‘diffractive optics’ comprising aberration-corrected holographic gratings. This ‘Aberration-corrected concentric’ design is shown below.

concentric imager

There are several advantages to this ‘reflective’ approach. First, the design is simple, temperature insensitive, and uses no moving parts. This assures robustness and reliability in airborne situations. Second, diffraction gratings can be made very small so that the instruments themselves can be small and light; in other words, capable of fitting the new class of lightweight, hand-launched UAVs. Third, the design optimizes technical characteristics that are most important: low distortion for high spatial and spectral resolution; high throughput for high signal-to-noise; and a tall slit for a wide field-of-view. Because the design is an all-reflective one, chromatic dispersion is eliminated and excellent focus is assured across the entire spectral range.

Many within the environmental research community and across ‘precision agriculture’ prefer to use UAVs as their primary airborne platform. They are more affordable than fixed-wing aircraft and easy to launch. But as UAVs get smaller and lighter, so must the payloads they carry. And integrating the sensor into the airframe along with other necessities such as LiDAR, power management/data collection hardware, and cabling can be a daunting task (Figure 3). Orthorectification of the collected data is another key requirement, which is the means by which the hyperspectral data cube is ‘managed’ into useful information that has been ‘corrected’ for any airborne anomalies. In other words, the collected hyperspectral data needs to be ‘true’ to what’s actually within the field of view.

 Micro Hyperspec

Acquiring a UAV and a hyperspectral sensor won’t assure compatible performance, and a high level of ‘integration work’ is needed. The UAV community and the hyperspectral sensor community are both challenged with pulling everything together. Recognizing this, Headwall Photonics is taking an industry-leading position as a supplier of fully integrated airborne solutions comprising the UAV, the sensor, the power and data management solution, cabling, and application software. The result is that users are flying sooner and collecting better hyperspectral data than ever before.

Type of UAV is very often one of the first decisions a scientist will need to make. Fixed-wing and multi-rotor are the two general categories, with numerous styles and designs within each. In-flight stability and flight-time duration are both paramount concerns, and this is where payload restrictions will often point toward one or the other. Multi-rotor UAVs launch and land vertically, so this type will be favored in situations where space is tight. Conversely, a fixed-wing UAV requires suitable space to launch and land but can provide longer flight duration and carry a heavier payload. The wide field-of-view characteristic of the concentric imager allows a UAV to ‘see’ more ground along its flight path.

Integrated airborne package

Two other key areas managed through Headwall’s integrative process are data management and application software. While a separate subsystem is used to control the sensor operation and store the hyperspectral data, the direction is clearly toward on-board integration of these capabilities. Flash storage and solid-state drives will soon make it possible for the sensor to ‘contain’ all the related functionality that now needs to be contained in a separate module. This will clearly lighten the overall payload, reduce battery consumption, and boost airborne flight time.

Headwall’s Hyperspec III software represents a complete, modularized approach to the management of hyperspectral data. Orthorectification is one such module within the software suite that removes the unwanted effects airborne behavior. The resultant orthorectified images have a constant scale wherein features are represented in their 'true' positions. This allows for the accurate direct measurement of distances, angles, and areas. Other aspects of the software suite can be used to control GPS/IMU devices, control multiple sensors simultaneously, and save polygons (A Google-map-enabled tool that allows the user to define geographic coordinates).

 

 

Tags: hyperspectral imaging, hyperspectral, Airborne, Remote Sensing, Micro Hyperspec, agriculture, diffraction gratings, precision agriculture