3DVW: We will begin by asking you how you came to choose your field of study and what attracted you to remote sensing and aerial imaging? What is your role at the University of Lethbridge in Alberta, Canada?
CH: As a child I grew up engaged by the stories of my grandfathers and their exploits during WWII. One captivated me with adventures and dangerous exploits in exotic lands and harsh times, while the other earned my respect for his technical work installing oft problematic auto pilot prototypes on bombers and reconnaissance planes.
These stories inevitably led to a passion for travel, maps and aircraft, which led me into scouts and air cadets as soon as I was old enough, and then a survey engineering internship between high school and university. My ambitions to become a high ranking intelligence officer in the Royal Air Force were irreversibly interrupted when my alpine glaciology honour’s thesis supervisor at Manchester University suggested I do graduate work in Canada. I was accepted into a Master’s program at Wilfrid Laurier University, where my research required an assessment of glaciological volume change in the Canadian Rockies. At the time and at the scale of interest, the only practical way to do this was using aerial photogrammetry. More exciting, was that the ground control to support such analysis was not in place; thus forcing me to conduct weeks of ground survey in exotic and harsh alpine environments in support aerial photo control. I could not be happier!
A few years later, I chose to continue the adventure in the Canadian Rockies by starting a Ph.D. but this time blending satellite land classifications, hydrological models and field geochemistry in an attempt to better understand alpine hydrology and water resources. After almost five years in Canada, the fiscal strain of being a foreign student forced me to look for full time employment. My survey, photogrammetry, air cadets and extensive field work experience were sufficient to get me a job with Optech as a LiDAR field manager. My time with Optech amplified my interest and expertise in aerial and terrestrial 3D laser remote sensing and laid the foundation for much of my research work since. Whilst at Optech, the company was very supportive of applications R&D and network outreach, which ultimately allowed me and some federal government colleagues to set up the Canadian Consortium for LiDAR Environmental Applications Research (C-CLEAR). From 2000 to 2011, C-CLEAR supported 100s of research-based airborne and terrestrial LiDAR surveys across Canada, and allowed countless university professors and graduate students access to data and support that would otherwise be impossible to obtain. In my professional career so far, nothing has given me more satisfaction than the knowledge that C-CLEAR was able to support the LiDAR research aspirations of so many individuals and organizations.
During the ‘C-CLEAR’ years, it was obvious that forest biometric assessment was an area of rapid growth in the LiDAR research community due to the high value of timber resources and increasing needs to assess carbon storages. Inevitably, this led to my research becoming split into three distinct areas: i) water resources; ii) technical/operational LiDAR; ii) forest biometrics. It was the combination of the last two that led to me taking a position with CSIRO in Australia as an environmental research scientist studying the integration of terrestrial, airborne and satellite 3D LiDAR data for forest carbon modeling and monitoring.
More recently, my desire to continue research in western Canada was fatefully met with the opportunity to take on the Campus Alberta Innovates Program Research Chair in Terrestrial Ecosystems Remote Sensing at the University of Lethbridge. As an Associate Professor in the Department of Geography, I teach remote sensing and physical geography courses, as well as supervise postdoctoral fellows and graduate students in my Canada Foundation of Innovation (CFI) funded ARTeMiS (Advanced Resolution Terradynamics Monitoring System) laboratory.
3DVW: Can you tell us a bit about your work as Campus Alberta Innovates Program (CAIP) Research Chair in Terrestrial Ecosystems Remote Sensing and what that involves?
CH: The ARTeMiS lab was conceived when I joined the University of Lethbridge early in 2013 but only recently became a reality when a CFI proposal submitted by myself and faculty colleagues, Drs. Hester Jiskoot and Laura Chasmer, was successfully funded. My colleagues, postdocs and students and I are still obtaining the hardware and resources to build up the lab capacity so we expect the system and applications to evolve as technology and understanding advance. In essence ARTeMiS is a hybrid terrestrial / mobile laser scanning and ground penetrating radar system that integrates above and below ground 3D data streams with complimentary imaging data sources. The system maps baseline ecosystem conditions and monitors changes in typically hard to access locations such as glacierized headwaters, boreal forest, northern permafrost landscapes and reclaimed wetland areas.
Setting up and equipping the ARTeMiS lab is my priority at the moment but in parallel, I’m supporting or leading a number of research projects in collaboration with provincial and federal government partners in Canada and overseas. For example, one of my postdoctoral fellows and I are presently finishing up two similar projects to assess biomass carbon change in forested environments in the Canadian Boreal Forest and the Australian Alps. Both studies use airborne lidar biomass models and aerodynamic CO2 flux models to extract the 3D footprint of the region that has undergone change due to growth, mortality or stand thinning operations. A study carried out in partnership with the Canadian Forest Service is integrating airborne and satellite lidar biomass models for parts of the boreal forest that will support forest inventory needs over large and remote areas in the Northwest Territories (NWT). Related to this project, we are using aerial lidar and satellite imagery to investigate surficial volume and feature changes due to diminishing permafrost in the region and its potential impact on forest biomass.
In recent months, two new projects have been initiated and are likely to remain a focus of the ARTeMiS lab for at least the next two years. The first is the development of an online portal to host and deliver lidar data and services in partnership with industry and government stakeholders in Alberta. The second is a provincial, federal, university, industry collaboration to develop a province-wide remote sensing water monitoring framework for Alberta that uses airborne lidar and synthetic aperture radar (SAR) data to map time series of winter snowpack and glacier changes in headwater regions and summertime open water inundation downstream.
3DVW: You have strong interests in lidar and high-resolution remote sensing. What kinds of research and studies are you involved in that use these technologies? Why are these technologies useful for the kinds of work you do?
CH: Since being employed by Optech and subsequently directing the activities of a lidar research lab in Nova Scotia, I have been very fortunate in my access to cutting edge terrestrial and airborne lidar technologies. Consequently, and serendipitously, my work since PhD has focused on environmental application testing or technical and operational lidar research. Now that I am back full time in a university environment, I am putting these experiences to good use in support of public sector mapping and monitoring initiatives or in assisting industry with the development of new lidar-related market opportunities. I’ve already mentioned some of the public sector monitoring research but in the private sector, we are working with lidar acquisition firms, geomatics service providers, consultants and even ski hill operators to help in some way with enhancing their business offerings.
Why lidar and why high res? Well, the world as we perceive it is inherently 3D and finely detailed. We collect and process Geomatics and remote sensing data with the anticipation that the data will be converted to information to aid in decision making. With high res lidar, the conversion of data to actionable information can be as trivial as constructing a digital surface model or as sophisticated as highly complex and integrative modeling workflows.
However, no-one can deny that simply visualizing a 3D point cloud of a city, a hill slope, a glacier, a wetland or a forest stand directly conveys a lot of information about the structure of that landscape without resorting to complex modelling procedures. It is the inherent realism captured in high resolution lidar data that makes this area of research so appealing. For example, I have been collecting airborne and terrestrial lidar data over glacier environments for 14 years. In particular, we have over a decade of data over the Peyto Glacier in the Canadian Rockies that illustrates extensive and large magnitude volume losses in areas outside the glacier ice extent. Without resorting to sophisticated or esoteric analyses, we can clearly visualize, quantify and understand the geomorphological mass movement processes taking place.
In the same area we previously generated photogrammetric surface models over a 40 year period but from these data it was not possible to discern these landscape change processes. Lidar has revolutionized terrain mapping in open and vegetated areas but for me, the real value is what we can now do in observing fine scale ecosystem, vegetation and landsurface dynamics.
3DVW: Most of the lidar related activities that we see in publish about all have common issues - those revolving around data volume and integration of point clouds into workflows. Can you explain why these are challenges what can be done about them? Is filtering or getting rid of parts of these data files to reduce their sizes the real answer?
CH: Data volume has always been a problem in this community. However, we have come a long way since the days of raw data collection on and extraction from exabyte tape and daisy chained 20GB hard drives that take up half of your desk! Yes, systems are faster and collect orders of magnitude more data now than when they first entered the commercial market but luckily, processing and computer hardware has kept pace and even gotten ahead in some ways such that data processing and analysis is much quicker and easier now.
Perhaps most significantly, the level of expertise required to enter the lidar 3D data processing and analysis world has greatly diminished. Off the shelf and proprietary software solutions are readily available and becoming more intuitive, and even mainstream GIS software is providing some processing capability. A lot has to be said for open source and semi open source software tools like Martin Isenberg’s LAStools that have allowed a new generation of university students and entry level practitioners get to grips with the data to perform in house QC, data cleaning, indexing and modeling.
Nonetheless, data volumes are still a limitation, even after employing freely available extreme compression like LAZ. Moving lidar data via ftp or other online methods is viable for small areas but not yet for large projects; at least not if we need to receive the data immediately. As bandwidth increases, this limitation is reducing and is highly variable around the world. But for now it is a real barrier for online lidar data and service provision. This is likely one of the reasons we do not see a preponderance of commercial or public sector online lidar data portals (for now).
One way I believe we will overcome such barriers (in addition to faster internet speeds!) is a shift in emphasis from client based data processing to server-based data product development. Such a shift reduces the need for end users to download, store and manage raw data as all raw data and processing will be handled remotely in the cloud. This leaves the user free to work only with the value added or derivative products they need, which also means smaller file transfers and less need for data processing expertise and software on the user side. A further benefit of this approach is it effectively opens up lidar data usage to a potentially high volume market base that currently has no capacity to handle or process raw data This is a philosophy that underpins our own data portal development activities.
Another area where data volume bottlenecks might be remedied in some cases is in better specification of lidar data acquisition projects and data density deliverables. We have come a long way since the ‘snake oil’ days (to quote an industry colleague of mine) of lidar data sales, where accuracy and application claims were made that could not easily be met. However, today, the user community is bombarded by manufacturer claims that faster and denser is better. It’s true, of course, that more can be done with higher density point clouds. For example, break lines can be better defined, features more easily distinguished, ground filtering or vegetation classification models better trained.
However, these improvements only hold up to a point, beyond which uncertainties in individual point position and attributes prevent further information extraction or clean visualization. We are frequently seeing data densities for airborne data sets quoted in the tens to hundreds of points / m2, yet for many of applications the data will ever be put to, such densities (and associated costs) are unnecessary. There certainly is a place for ultra-high resolution data but I would caution those responsible for contract specification to base data requirements on a solid grasp of project needs and data limitations, rather than simply assuming that the highest data density will produce the best results. It frequently happens that after a dataset is delivered, it is thinned by several factors in order that data can be efficiently handled and analysis proceed. If data thinning is considered a legitimate solution, then one needs to question the requirement for high density in the first place.
3DVW: In Alberta and Canada, what do you consider to be the major challenges for ecosystem remote sensing? Is the Province of Alberta meeting the challenge when it comes to high-resolution remote sensing for the environment, or could it be doing more?
CH: I’m a new Albertan but I believe there are three hot topic areas that overlap with my ecosystems remote sensing research mandate: i) forest health and inventory; ii) water resources and flood risk; iii) oil and gas sector resource extraction and site reclamation in ecologically sensitive areas. I have studied in Alberta since 1995 but only lived and worked here for a little over a year so still have a lot to learn about provincial monitoring and stewardship of the environment.
It is clear the Government of Alberta takes this responsibility seriously (they’ve funded much of my research since being a student!). At present the government is setting up a new Alberta Environmental Monitoring, Evaluation and Reporting Agency (AEMERA) that will manage existing monitoring programs and explore new approaches, including remote sensing, to improve land stewardship and regulation. It’s too early to have any opinion on AEMERA’s success and based on the record of existing and previous monitoring programs it’s always easy to say that more could be done if time and resources were infinite.
However, in this respect, my experiences with Alberta’s previous Sustainable Resources Development and Alberta Environmental Protection Agencies have demonstrated a clear willingness to work with academics to explore new remote sensing based approaches to monitoring and managing the environment. I find this encouraging, though there are always sensitivities where industry resource extraction or urban development interests threaten, or are threatened by, a desire to maintain sustainable ecosystem functions.
As an academic, this makes Alberta an interesting place to study. Particularly, as the need to monitor and track ecosystem changes and disturbances is becoming obvious to all stakeholders and an increasing reliance on remote sensing seems assured. The obvious benefits are cost per unit area being mapped or monitored but perhaps of greater value is the consistency in data product that can be achieved over large areas. For monitoring purposes, product accuracy is obviously important and this is where remote sensing can fall down at site level compared to field sampling. However, the potential for remote sensing data product consistency through time and space can offset, even trump, accuracy concerns as the information generated concerning spatio-temporal ecosystem change trajectories can more effectively inform policy and management decisions. Building on this premise, we aim to deploy ARTeMiS as part of a scaled ecosystem remote sensing monitoring system to provide consistent semi-automated site-level data to help calibrate airborne and satellite derived products.
3DVW: Unmanned aerial systems or vehicles (UAVs) have become popular in many parts of the world, and Europe seems to have a lot of research activity in this area. Are you involved in this kind of technology and what are some of the efforts in Alberta that involve this research and development?
CH: With the recent CFI proposal, I did consider UAV lidar. Moreover, colleagues of mine in the Alberta Terrestrial Imaging Centre (ATIC) and the University of Lethbridge do work with UAV imaging systems. It is a tempting area to get into and the University is currently developing a multimillion dollar business incubator that will integrate a range lidar 3D imaging technologies including UAV. I will be involved in this project but at the present time it is unclear how the initiative will be organized and coordinated. For now, I think there is almost too much to do with the current range of technologies and research problems that ARTeMiS is already engaged in, and UAV lidar might prove to be a distraction given the current staff and student compliment. However, I recognize this is a direction we have to go in, as there is obviously great potential in the ecosystem monitoring application area. Particularly as related to forest health (e.g. pine beetle infestation), crop productivity, land reclamation, glacier recession, snowpack depth sampling etc.
3DVW: Last year there was a Lidar Forum held in Lethbridge, what was that all about? What did you learn from the event?
CH: The lidar workshop at Lethbridge in 2013 hosted stakeholders from provincial, federal and municipal government, industry and academia so that we could share multi-sectoral perspectives on the need for lidar data and procedural standards, and best practices. Some of the challenges faced by public sector BIG DATA users were illustrated as well as some of the opportunities for market expansion for commercial providers. Less than a month prior to the workshop, Alberta suffered the worst floods in living history. It was clear to many participants that other jurisdictions around the world had adopted lidar operationally in flood prediction and mitigation so this also became a source of some hot debate given Alberta possesses the largest lidar data coverage of any province in Canada. As a result of the public sector data management and dissemination challenges, and potential private sector market opportunities, a small group was formed to put together the lidar data portal proposal described above.
This year, we are hosting another workshop with a similar mix of stakeholders but this time the theme is focused on lidar and remote sensing image integration in support of water monitoring needs. Results from this workshop will inform some of the design elements of the data portal and the water monitoring frameworks our group is working on.
3DVW: Can you describe some of the activities that your students are involved in that include high-resolution technologies? Do you have affiliations with others in the province that includes education and training?
CH: The ARTeMiS lab compliment is small at the moment with a handful of postdoctoral fellows, Ph.D., Masters and Honors students. In addition, several other undergraduate and graduate students have become part of the extended lab compliment through involvement on small contract research projects or independent study projects. I am promoting team work in research and classroom projects to better mimic real world approaches to solving complex systems-type problems. This invariably involves a balanced mix of field and lab work, as well as direct interaction with the ‘client’ or source of the problem or need. Recently, a group of my students worked on a mountain watershed study that was supported by airborne lidar and other optical image products to assist with the set up and parameterization of a hydrological model. They tested ski hill development as well as forest management scenarios.
One of the students, Dave, has decided to take the work further for his Master’s degree to further investigate the ecology and disturbances in the watershed using aerial and terrestrial lidar data. Another Master’s, Josh, will be building on lidar wetland classification research conducted by one of the postdoctoral fellows, Laura, to develop an enhanced remote sensing-based wetland functional assessment framework. Meanwhile my other postdoc, Craig, is leading ICESat satellite lidar forestry research, Zhouxin’s Ph.D. will focus on 3D models of forest canopy radiative transfer and foliage cover and Husam is starting to lead some of the lidar database and processing aspects of the lidar portal for his Ph.D. thesis. My Honor’s student, Reed, is playing a key role in maintaining and programming the ARTeMiS lab instrumentation while building a thermal imaging system for periglacial monitoring of buried ice and melt processes in high alpine watersheds. I am in discussion with other student and postdoctoral fellow prospects to assist with mountain snow and glacier monitoring as well as lidar / SAR water mask integration research.
The ARTeMiS lab is fortunate to be affiliated with the Alberta Terrestrial Imaging Centre (ATIC), which hosts the Amethyst student training program funded through the Natural Science and Engineering Research Council (NSERC). ATIC and Amethyst play an integral role in helping maintain the ARTeMiS lab through connectivity to like-minded faculty, and support for students and postdoctoral fellows working out of the lab.
Recently, a group of renowned lidar researchers across Canada submitted another NSERC proposal to set up a national lidar training program, which if successful, will link ARTeMiS to this national network and extend collaborative opportunities for students. In this new initiative, as well as Amethyst and ARTeMiS, there is a tendency towards more applied research and connectivity to public and private sector stakeholders, as we find more and more this is what students and outside partners are looking for. This does not preclude pure science or curiosity driven research but it does make it easier for our students to connect their learning to real world opportunities after graduation.
3DVW: Many of our readers will be interested to know how useful lidar and remote sensing is for measuring and monitoring snow. Could you explain how these technologies are used in snow measurement and why you find them useful?
CH: Before I was an employee of Optech, a close friend of mine, Mike Sitar, at the company who shared the same passion as I for mountains, glaciers and snow educated me on the basics of airborne lidar. Once you understand that lidar can produce a high res accurate digital elevation model (DEM) of the ground surface (even beneath dense foliage cover) it doesn’t take any kind of brilliance to appreciate that a DEM captured during snow free conditions can be subtracted from a DEM captured during snow covered conditions to produce a snow depth map.
As is often the case with new technology, applications and science in general, turning idea into reality can be slow and frustrating. After obtaining the necessary ground survey equipment and planning the airborne survey, we conducted our first tests in the winter of 1998/99 north of the offices in Toronto. It had taken months to coordinate and coincide the logistics with snow deep enough to improve our chances of success. Alas, the early generation ALTM 1020 failed on the day and so we lost our opportunity. The next opportunity did not avail itself until winter 2000/01, two years later. The test was simple, and the results published in preliminary form in 2002, then formally in 2004.
Unfortunately, snowpack around Toronto is not reliably deep enough at end of winter to seriously consider such monitoring methods. Nor does it play as critical a role in water resource policy and management as it does in regions where snow is the largest contributor to annual water resource or flood risk, such as in western Canada. Consequently, these early tests went no further and the application was not implemented. Moreover, in 2001, the idea of lidar supported snow sampling was unreasonable due to high cost and low accuracy. In 2008, however, the technology had advanced such that the Government of Alberta and City of Calgary supported a pilot study over a key watershed upstream of Calgary in the Canadian Rockies.
Costs and accuracy were still found to be barriers to implementation. Now, in 2014, we see other jurisdictions (e.g. California) where the costs and accuracies are now considered practical relative to the resource management gains associated with improved headwater snow cover and depth data. Here in Alberta, we are fortunate to have most of the province mapped with lidar and we are once again in discussion with the Government of Alberta to explore the viability of operational snowpack monitoring as a supplement to traditional field and helicopter based snow coursing.
3DVW: Is there a particular benefit of 3D when it comes to education? Are students more or less interested in studying ecosystems in 3D?
CH: In short, the ‘cool factor’ associated with lidar 3D graphics is a great aid in the class room! Whether the data are used to illustrate tree branch and stem architecture, forest canopy cover, snow depth or glacier changes in alpine environments, having such graphics available goes a long way in promoting student engagement and interest. As a teacher of Physical Geography and Geomatics courses I use airborne, mobile and terrestrial lidar graphics whenever possible to illustrate attributes and processes of our physical environment. Having access to high res 3D data makes it orders of magnitude easier to describe these environments and the subtle details that are lost in 2D maps, diagrams and textual or verbal descriptions.
If they say a picture tells a thousand words, then I believe a 3D image tells a million words! Of course, we are at the point where even mere 3D is becoming ‘old school’, as we are now visualizing 4D time series of lidar-based environmental change processes like forest growth and geomorphological slope processes. Further we are attributing these point clouds and models with colours and textures derived from complimentary imaging systems to add further dimensionality and information richness. We live in a media rich world and teachers have to compete with all manner of distractions to captivate students. Good pedagogy cannot rely on the cool factor that lidar provides, but it really does make it easier to communicate complex phenomena without resorting to the abstract thinking that was necessary when my generation sat in lecture theatres with little but the professor’s voice, chalk scrawls and arm waving to keep us engaged!
Chris Hopkinson is a Campus Alberta Innovation Program (CAIP) Research Chair in Terrestrial Ecosystems Remote Sensing and an Associate Professor in the Department of Geography at the University of Lethbridge. Prior to 2013 he was a research scientist with the Commonwealth Scientific Industry Research Organization (CSIRO). His research focuses on developing terrestrial, airborne and satellite lidar monitoring workflows in forest and watershed environments. He has served as chair of the American Society of Photogrammetry & Remote Sensing, lidar committee and directed a lidar lab in Nova Scotia where he led a national lidar consortium known (C-CLEAR). As well as serving as an associate editor for the Canadian Journal of Remote Sensing, he has served in executive positions in the Canadian Water Resources Association and the Canadian Remote Sensing Society. His ties to the lidar industry have allowed 100s of students and interns unique experience with cutting edge lidar technologies and data. He currently supervises postdoctoral fellows, graduate and undergraduate students through the ARTeMiS laboratory in Lethbridge and previously supervised several grad students in an adjunct capacity at Dalhousie and Acadia Universities. As a manager and research scientist, he has supervised many technicians and interns, and has published extensively on the applications of lidar in the environmental sciences. His current research program at the University of Lethbridge is funded for the next 5 years through CFI, CAIP, AI-TF, ESRD, and NSERC. He enjoys anything related to having fun in the mountains, riding his Moto Guzzi, spending time with his wife, Laura, and two children, Brynn and Elan, as well as growing food for their kitchen table in their small back garden.
Dr. Chris Hopkinson, CAIP Research Chair in Terrestrial Ecosystem Remote Sensing, Associate Professor, Department of Geography, University of Lethbridge, Lethbridge, Alberta T1K 3M4
Interview: An Alberta Perspective - Understanding 3D-4D Terrestrial Environmental Change Processes and Terradynamics
- Category: Interviews
- Written by Jeff Thurston