Skip to comments.Laser scanning reveals 'lost' ancient Mexican city 'had as many buildings as Manhattan'
Posted on 02/17/2018 10:15:51 AM PST by mairdie
The approach, known as light detection and ranging scanning (lidar) involves directing a rapid succession of laser pulses at the ground from an aircraft.
The time and wavelength of the pulses reflected by the surface are combined with GPS and other data to produce a precise, three-dimensional map of the landscape. Crucially, the technique probes beneath foliage - useful for areas where vegetation is dense.
The team also found that Angamuco has an unusual layout. Monuments such as pyramids and open plazas are largely concentrated in eight zones around the city's edges, rather being located in one large city centre. According to Fisher, more than 100,000 people are thought to have lived in Angamuco in its heyday between about 1000AD to 1350AD. "[Its size] would make it the biggest city that we know of right now in western Mexico during this period," said Fisher.
(Excerpt) Read more at theguardian.com ...
A tiny storage shed and the Chrysler Building are both a single building, but I have hard time getting excited about seeing the former.
i fail to see how it goes through the trees/leaves
Still doesn’t say what happens when the leaf canopy is solid.
Seeing the Forest Through the Trees with a New LiDAR System
“The real key to making our system work is the interference between two laser beams on the sensor. We send one laser beam out to the target and then it returns, and at the exact same time that return [beam] hits the detector, we interfere it locally with another laser beam,” Watnik said. “We need complete coherence between those beams such that they interfere with one another, so we had to have a specially designed laser system to ensure that we would get that coherence when they interfere on the camera.”
Using a pulsed laser with pulse widths of several nanoseconds, and gated measurements with similar time resolution, the holographic system selectively blocks the earliest-to-arrive light reflecting off obscurations. The camera then only measures light coming back from the partially hidden surface below.
How is LIDAR data collected?
When an airborne laser is pointed at a targeted area on the ground, the beam of light is reflected by the surface it encounters. A sensor records this reflected light to measure a range. When laser ranges are combined with position and orientation data generated from integrated GPS and Inertial Measurement Unit systems, scan angles, and calibration data, the result is a dense, detail-rich group of elevation points, called a “point cloud.”
Each point in the point cloud has three-dimensional spatial coordinates (latitude, longitude, and height) that correspond to a particular point on the Earth’s surface from which a laser pulse was reflected. The point clouds are used to generate other geospatial products, such as digital elevation models, canopy models, building models, and contours.
>>A shed converted into a Titanic replica.
And how many of those do you assume were in that lost city?
While we are arguing about comparative cultures as defined by building count, let’s compare sewer and water service too.
And yet less Mexicans.
But a third of the buildings were s-holes.
I would imagine that the two Mexicos described in Lewis’ Five Families was there then, too. The rich had the best. The poor barely survived. And there were always more of the poor. They’re not saying this was a great civilization. Just that it was larger than we think because it’s sunk beneath our memories as thoroughly as it has sunk beneath the ground.
>> The rich had the best. The poor barely survived.
That is the history of humankind in a nutshell. Only the prosperity created by a free America with a Protestant work ethic has allowed the two worlds to even come close to being similar. And as we discard the Protestant work ethic in favor of the Third World kleptocracy, the two will diverge once again.
You’re absolutely right.
The Protestant Ethic and the Spirit of Capitalism
Blockies! Comment if you get the reference!
Poor, poor pre-Mexicans. Global Warming did them in. All those horses, methane, etc.
Totally flummoxed. Will have to fall on your mercy in explaining.
It eats, shoots, and leaves.
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