By HHA Member Tom Helmer
Lidar Maps by Carol Baker and Kathryn Zuromski, Laser Scans by Al DiOreo
I first heard of Lasers when I was in High School c.1965. I also remember they were called “The answer to a question that had yet to be asked”. A product of scientific research, they had no application using them, but they did have the best safety warning sign I have encountered down to this day:
Do Not Look At Laser With Remaining Eye
50 years later lasers are unremarkable, an inescapable technological part of our lives. But recently, HHA had 2 encounters with laser applications which were stunning. The first was Lidar Mapping of the great outdoors, the second was 3D laser scanning, not of supermarket bar codes, but an entire building!
Somewhere along the way, someone discovered that if you flew an airplane with a laser pointing down and scanning rapidly back and forth, and recorded the reflections coming back to the plane, and ran that data through the Transmogrifier, you could render the trees invisible and see the underlying topography hidden beneath the forest canopy. Or, you could focus on the reflections coming back from that same forest canopy and see the mixture of specific species of individual trees in the forest below. Or you could search for certain characteristics to find special habitats across broad swatches of the landscape.
Big Deal. So What.
By scanning for special plants, wetlands can be rapidly identified. (So can pot farms hidden in the woods)
Forestry can monitor overall tree health and the expansion/contraction of specific species.
Archaeologists can spot likely old roads, ruins and areas of interest to guide “on foot” investigation.
This one excited Hopkinton’s Land Trust, Conservation Commission & Historical Association.
Carol Baker, who is a GIS Professional, (Geographic Information Systems) gave a Lidar presentation to 15-20 interested people at Town Hall, and supplied us with maps to let the technology do it’s thing.
Here are several images of an area in Hopkinton
View from Google Earth
In that sequence, it was possible to deduce there were stone wall boundaries to the fields on the right from Google Earth, but you see the presence of a cemetery in the upper right corner of the top field? Look for it in the Lidar Map,then see it’s small stone walls outlined in the Field Guide. On the tree covered Left side of the Google Earth picture, did you see the radical topography hidden beneath the tree canopy? Did you see the faint outline of dual stone walls lining old farm roads? It would take a hiker days to map these details, but only hours to confirm the Lidar interpretations.
HCC and HHA have begun to use Lidar mapping to further explore the Canonchet Preserves. The foot exploration is covered in depth on the page “Making The Canonchet Trail”, but here is the web site’s first peek at a composite Lidar map of the huge Canonchet Preserves.
3 D Laser Scanning
After the meeting in Town Hall where Carol was showing us Lidar, Al DiOreo, our local surveyor, approached Rick Prescott about using some new technology to create a 3 Dimensional Laser Scan of the HHA Meeting House, pictured on our Home Page.
This building was built in 1790, and Al said what he wanted to do was create an architectural 3 D drawing of the entire exterior. This would not be some fancy composite photograph, the information he would collect would consist of millions of discrete data points, and each one would be in perfect spatial relationship with every other individual data point.
In simple terms, just like an architect’s blueprint showed the dimensions of major details, his 3 D scan would allow measurements on demand all over the building. But unlike an architect’s drawing, the measurements would be derived via the laser, not a crew working off of scaffolding using tape measurements. This produces an accuracy orders of magnitude superior.
Al set up his equipment with a surveyor’s precision, (Garbage In, Garbage Out) his machine did it’s scan, and when the data was processed, he had an exact digital model of HHA’s Meeting House. With the proper computer software, you could manipulate this model in any plane, measure the radius of the molding on the steeple, the dimensions of the door, or count the floats on one of the shutters.
He also gave us a presentation in the Meeting House, and presented Rick with the copy of the entire building on a thumb drive.
The applications for this technology are growing. You can exactly duplicate a building, both interior and exterior. You can direct restoration maintenance on old buildings to the precise spot needing work, and often figure out what is causing the problem to fix that, as well as the symptom.
You can alter the detail to reproduce the finest nuances of sculpture, The topography of land, or the archaeology of ancient structures. Here are the photos of Al at work, and a print of the visual representation of the building’s model. As always, when local businesses work with HHA, we showcase their business card as our way of saying “Thanks!”