LiDAR in the Field: Using High-Tech Equipment in Resource-Challenged Areas

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Source: Wikipedia.com

One important aspect of our research in both Oto-Awori and Itire-Ikate required the use of remote-sensing technology. We intended to capture the proximal nature of open water, boreholes, and other relevant infrastructure in the communities we visited in order to inform our research and provide a spatial richness to our data. The use of airborne laser devices is among the cutting edge remote sensing technologies – but is not brand new. This LiDAR technology (a combined acronym born of “light” and “radar”) uses a combination of laser and light to assess topology and create high-resolution maps.  For years, municipalities and emergency researchers have used LiDAR-based aerial photography to view and identify dense forest areas and flammable foliage for fire modeling, or to most accurately trace street network centerlines or create building footprints – just to name a few functions of many. Because LiDAR pinpoints so accurately the features of the earth’s surface and reads the reflection of light from millions of those points, it is the most capable way to perform remote sensing from above. But LiDAR technology is innovative in that its applications are endless as the technology improves, and some researchers have taken LiDAR equipment into the field to assess topology from the ground, where areas with extreme drought effects or crumbling infrastructure can be mapped more accurately than it could from the air – all of which are highly relevant to our research in Lagos.

To test this endless functionality, our own UC Berkeley research team took LiDAR equipment all the way to Lagos, Nigeria to aid in our understanding of local water infrastructure in underserved informal communities. Our hope was that we could capture some quantifiable surface data to complement our community surveys. While evidence points to some potential benefit to terrestrial LiDAR scanning in the informal  or slum environment, our group was unable to capture these. This is an attempt to illustrate those perils we encountered and to provide guidance from our troubleshooting experience for future researchers in the developing world.

Equipment

Maptek I-Site 4400 Scanner Source: arf.berkeley.edu

Maptek I-Site 4400 Scanner
Source: arf.berkeley.edu


Our team procured a Maptek I-Site 4400 from an affiliated department at UC Berkeley. Weighing in at about 30 pounds, the scanner alone is worth nearly $100,000. The accompanying equipment includes a tablet for use with the scanner, a delicate but essential tribrach mount, and a heavy-duty surveying tripod. This, combined with all the necessary wires, batteries, and padding was divided into two cases, each awkward and hefty in its own right, and transported by plane as checked luggage to Nigeria.

Experience
Power source woes
We made it through customs with only some snags once in country, which is its own harrowing experience without the added stress of transporting expensive survey equipment. Once we were safely delivered to the guesthouse, we tested the equipment one last time. Overall the set-up process was pretty intuitive after doing it a few times on campus before we left for Lagos. In the guest house in Lagos, however, we ran into problems. First, in classic amateur fashion, my attempt to charge the spare battery failed and in fact destroyed our only ground charger. One of the professors supporting our project ribbed me later, claiming this was a wholly generational issue. In what way? Well, back in the day, there were clear distinctions between plug adapters and voltage converters. Today, my fellow gen x-ers and millennials have “no sense of these things,” which is how I fried the charger with my plug adapter (which is not the same thing as a voltage converter). I would argue that correlation ≠ causation, but I’ve been outvoted.

This seemingly small mistake (generational correlation notwithstanding) set us back pretty badly, actually. Our Maptek I-Site is specialized equipment requiring a specialized power source with a specialized charger. In the states, the charger could be found for around $100 USD in a Radio Shack. In Lagos, Nigeria, there were no such connections – at least not readily searchable. Fortunately,  we did have a car charger on hand, and we thought this would suffice as we were planning to be in transit for upwards of 5 hours at a time. Sadly, this didn’t work as well as we’d planned.

Charger woes
We selected our scan sites based on proximal infrastructure and conditions. We wanted to identify our sites using five indicators, and hoped that these categorizations would remove any “scan bias” and provide a variety of terrestrial surfaces and conditions for our research. The five indicators we settled on for identifying sites were:

  • Flood areas
  • Water infrastructure
  • Open water area
  • Boreholes
  • Waste areas

 

Sewer infrastructure

Sewer infrastructure

We were able to locate many of these kinds of sites in both Oto-Awori and Itire-Ikate. However, setting up the Maptek I-Site scanner on campus or even the guest house proved to be much easier than it was in the field.

First, the equipment was very heavy, and the accompanying cases were not designed to be carted over rough, wet clay terrain. There was one instance in which our van became lodged in a hole. In the interest of time, my team and I got out and attempted to wheel/drag the scanner case along a precarious wall above an open sewer.

Second, it was extremely hot in Nigeria. The scanner and tablet became heated quickly – and while this is strictly anecdotal, I believe the Windows tablet we were using to connect with the scanner was much slower and less responsive in that heat. This compounded the problem with the battery, which was not able to charge fully in the car, despite being plugged in for 3-5 hours. Because of this, time was of the essence every time we found a site, and several times we could not get a complete scan before the battery drained.

Open water

Open water

Third, we drew a crowd. In less developed informal settlements like Oto-Awori and Iteri-Ikate, LiDAR scanners are unreal to many residents. Some had questions, others were distrustful, but most gathered around while we were attempting to scan. While we had local helpers asking people to move away, curiosity won over in every case. Because the scanner is dangerous to the eyes, we needed to be clear of the populous. Further, to get a good scan of the terrain, the populous had to be clear of us.

Due to these factors, every single time we set up, the battery died before we could complete a scan, which means we weren’t able to capture useful terrestrial data for our study.  While this aspect of our trip was ultimately unsuccessful where readable scans were the goal, in terms of learning experience, the trip was a huge success. Experience has given us the  tools to be more prepared to meet the challenges of using this type of remote-sensing  equipment in the field. Electricity might not be consistent in your study area, and the weather may be unpredictable. Heavy traffic could be detrimental to time management, or the equipment itself could be damaged by a power surge (through no fault of your own).

Open sewer along a road

Open sewer along a road

I am personally disappointed that we weren’t able to gather the terrain data we wanted, but all of the problematic aspects of our experience with the LiDAR technology provide both useful takeaways to be applied elsewhere in the future. Maybe even another research trip to Lagos!

Stay tuned for another post on how to set up and use the Maptek I-Site 4400 for terrestrial surveying.

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