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lidar imagery remote sensing laser optics
I think the engineering behind how we create Lidar (Light Detection and Ranging) based surfaces
is pretty eloquent and cool! It's also feasible to teach in a short video. The general concept is that we place a laser ranging instrument on a platform (usually an airplane), have a rotating mirror (as you're polling hundreds of thousands of samples per second, it would be crazy to try to spin a heavy instrument like that so fast) that the laser bounces off, travels towards the ground and reflects off a surface either partially or fully as you can recieve multiple responses. A point cloud is generated for the study area, which can then be interpolated into a surface.
The key topics to cover would be:
Lasers (particularly how ranging works)
GPS and Inertial Management Units (IMU) which determines the relative position, aspect, zenith if your platform (often an airplane)
Basic trigonometry (If you know the x,y,z of one point, the vector and the length of a line, then you know the x,y,z of the other point!)
I've always found that when trying to tell to people about what I do as a geographer, Lidar always catches their attention. Being able to capture a surface from the sky at 5-15 centimetre resolution is exciting to be sure! If people find this to be an interesting topic, I'll fill out quite a bit more here when I get a chance.
Please add comments, suggestions, points for discussion below. Also, feel free to modify the description above.
[Very interesting: I wonder if this could go with signals in some way; or is there a series on imaging in general. bill-engineerguy]
[It certainly could go along with signals, though a better example would be spectral remote sensing (visible light, radio, microwave). In my grad work I've come to learn that Lidar is very much a different beast from traditional spectral remote sensing techniques. In this case we're measuring distance/position and rendering topography rather than spectra over an even spatial resolution. The intensity of the signal return is of value, but to a lesser extent than the spatial component. Andrew - original poster)
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