Geo Positions: Detecting Change Over Time With 3D Models
Upon obtaining a degree in geography from the University of Dusseldorf in Germany about 10 years ago, Sandra Bond came to the U.S. as an exchange student to write her thesis on the San Andreas fault. “Then I just ended up staying,” she says. At that time she was in search of professional opportunities in the geographic field and landed an internship with the U.S. Geological Survey (USGS) in Sacramento, Calif. Now, a decade later, she has worked her way up to the role of geographer and LiDAR analyst. Unfamiliar with the technology initially, she says she was fortunate to have been exposed to it right away when she started, thanks to a supervisor who found the technology interesting at a time when it was considerably new.
Today Bond works mostly with terrestrial LiDAR processing and 3D visualization. Along with her colleague, she conducts surface change analysis mostly regionally and sometimes nationally. “That means we repeat scans in the field after different time periods and then analyze to see what has changed between the scans,” Bond says. “We’ve done that for wildfire and post fire erosion, we’ve done that for surface settlement after earthquakes, and we’ve done that in Alaska for glacier advancements.” Her colleague handles most of the data acquisition in the field and she does most of the post processing on the computer.
The most enjoyable aspect of the job is that no two projects are the same, she says. With new questions to answer and problems to solve every time, she says she likes that it never gets repetitive. While unfamiliar encounters can introduce challenges, she finds them worth it. “You have to go into it with a new pair of eyes every time you’re starting a new project and that’s very rewarding in a sense, because you’re not just pushing a button.”
One of her favorite projects involved surveying a jetty that was built by the Army Corps of Engineers to assess its overall stability in response to the storm tides in Hawaii. Her team surveyed it a total of three times and created a colored map of how the concrete jetty blocks moved over time, which was shared with the public. “It was a project that was really fun. Not just going to Hawaii, which is a fun place to go to, but also the project itself was very different from the other projects we did here in California.”
Q. What do you do for a living?
A. Generally speaking, I do the post processing of LiDAR data acquisition. I mostly work with terrestrial LiDAR. I do have a little bit of experience with airborne LiDAR as well, but not as much. My typical day involves processing and analyzing the data that comes in from my field -. After the initial alignment process, we have a quality assessment and control session where we rigorously check the alignment of all scans and make sure that we don’t have any data gaps or errors. We want to make sure that our data is solid and that we believe what the data is telling us. Then we basically think about how can we display this data, how can we give it to whoever can make use of it, what kind of format can we give it to them in, and how can we visualize the results, not just for the scientific community, but also for the public.
Q. What is your favorite tool to work with?
A. Since I do a lot of processing work with the computer, I’m very lucky to have the opportunity to work with a 3D immersive visualization environment. I’m not just looking at the data on my computer screen and regular LiDAR software, but I can take it into a 3D environment where I’m actually wearing 3D goggles and I’m looking at my data in actual 3D. I have found over the course of the past few years that having that tool as part of my work process is very, very helpful with actually assessing the data and making sure that the alignments done in the processing software are accurate because a lot of the time, you can’t see certain angles in a 2D environment on my computer screen, because it’s not “true” 3D even though it might look like it. In that 3D immersive environment, you can actually “walk around” in your data set and you can really see how well the alignment processing went and what the results are that you’re looking for.
Q. What is the toughest challenge you face?
A. The biggest challenge is that we’re constantly pushing the computer and software capabilities because the LiDAR data is notoriously large and the scanner can collect more and more data in less time. So the data sets are big and they get bigger and bigger. It’s usually a challenge to decide how much data we can actually process in one batch. We have to filter or subsample the data in order to work with it and just to keep up with the demand for new applications, just hitting that limit on the computer to deal with what you’ve collected. That sometimes is a challenge.
Q. What is the biggest lesson you’ve learned?
A. I would say the biggest lesson is that every project is different. It’s also the most fun part for me, but it’s the biggest lesson, that none of the sites that we look at are the same. Every survey and every processing step has to be carefully planned and we learn new tricks every time we go out and we set up the survey and really have to think about what we want to achieve and how we want to set up our survey. It’s a rewarding and challenging process because not every project is the same and you have to kind of get creative with the approach you take to whatever task is put in front of you.
Q. What advancements would you like to see made?
A. I’d definitely like to see the technology expand and get more mainstream so more people can take advantage of it, because I think the really big advantage of LiDAR is that you’re not getting just numbers as results. Often when you take measurements, you look at numbers as results and with LiDAR you don’t just get very active measurements, but you can also visualize them in 3D, which if you have a 3D model of the actual world. It explains so much more than just having numbers thrown at you. I think the more people know of the technology, the more people will see there is a need for it in very different fields. Over the last few years we’ve seen it expand and go into different areas. I remember LiDAR was first used, I think, as an engineering tool and now we’re taking it out into the real world and measuring scientific questions with it.
Q. What are your keys to success?
A. I think persistence and patience are two words that come to mind for me because I remember when I was first being exposed to LiDAR and a lot of the software that came out at the time, I didn’t get real official training for, so I had to feel my way in and sort of teach myself how to use it. Having that persistence and patience, and looking at what I wanted to achieve at the time, I was told by my supervisor that he really appreciated about me that I was willing to just sit down with it and figure out a way. I feel like this has helped me a lot with every project I’ve been involved in, just because, as I said, every project is different. Having a creative approach and patience and the willingness to explore different paths to get the results you want seems to be the biggest keys for me to make things work.