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Steve Herschbach

Light Detection And Ranging (LiDAR)

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Wish I had views of my area like this, were literally on the oregon trail. Several places I heard of here are forested hiding the old campsites. Also the old stage stops would probobly show up. Pretty cool stuff, instant history.

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"Something there is that doesn’t love a wall,

That sends the frozen-ground-swell under it

And spills the upper boulders in the sun,

And makes gaps even two can pass abreast."

Robert Frost nailed it.

All the New England farmers got tired of stacking rocks and moved to Oregon over the Oregon trail. "Abandoned New England Farms" were all the rage in the early 20th century for city folks to fix up.

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In Nevada, where heavy vegetation is nearly unheard of, you can see pretty much everything with Google Earth.

In the heavily forested sierra gold country, Lidar would be amazing.

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That's world class stuff right there.  Can't wait to see more of this!!

 

Thanks for sharing.

 

Kenny

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More on LiDAR - they discovered Roman gold mines in Spain! We have detector guru engineer Dave Johnson to thank for this link:

 

http://www.laboratoryequipment.com/news/2014/11/airborne-laser-finds-roman-goldmines?et_cid=4277812&et_rid=281012844&type=cta

 

Now if we could just see underground like that!

post-1-0-68822300-1416597525_thumb.jpg

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Low resolution raw LIDAR data is publicly available for free for about 1/3 of the United States, mostly the east coast and developed areas. High resolution LIDAR (1-3 cm) is available in a few areas. Mostly for environmental studies or only available privately.

 

Without LIDAR we have to rely on DEMs (Digital Elevation Models) for elevation data. These are mostly just a rehash of the old paper topo maps with hand drawn elevation lines converted into even lower resolution digital point shapes represented by light and dark shades on an artificial black and white image. The shades of gray of each pixel represent different elevation values. These DEMs have a high factor of human input error. Mountains and valleys sometimes appear wher there is nothing but a road or a visually confusing feature on the original topo map. If I were to describe the conversion method for these topo's derived DEMs I'm sure you would be in awe of the influence of primitive technology in our "modern" lives.

 

LIDAR is really just a (sometimes) higher resolution version of this system with the difference being the LIDAR points are defined by direct reflection of a laser light rather than ground observations with optical equipment, geometry and trigonometry - traditional survey equipment and methods. The final result in either case is still a grid of values most usually visualized and stored as a photo image in shades of gray. Although just about any data storage format will work humans still naturally understand complex data with their eyes better than any other sense.

 

The features you see on your link were buried in the original LIDAR data. A lot of post processing (number crunching) is necessary to turn the raw data into detail like you see on the website linked. In other words the LIDAR system itself is not discriminating out the trees and ground cover. That is done by applying some pretty complex algorithms to the data after the fact. All of that processing actually lowers resolution and accuracy. To be truly effective for any particular purpose those algorithms are usually customized to the project requirements.

 

We use LIDAR on some of our private mapping projects along with matching high resolution georectified aerial imagery. This can reveal several features you could never see from the ground or the air. We can build 3D models that very closely conform to reality and move through those models in three dimensions. This is a very realistic process and allows us to include measured, extrapolated or even sensed data for underground features. Mining companies love this stuff, not so much for project management but for making presentations for investors.

 

The size of the data involved is a very real problem. Terabytes of data are needed for even a small area and processes take a very long time to run on data that size.

 

Just obtaining the data can be a very long process. We can order a LIDAR scan of just about anywhere in the world but the logistics of producing that scan can be overwhelming. A good high quality scan requires several manned precisely located ground stations as well as some very expensive aerial equipment. Just getting the time booked can be a long wait and getting the skilled ground and air crews working together under ideal conditions can be a virtual impossibility. Add in the difficulty and expense of placing those ground crews on landlocked parcels, hostile territory, difficult terrain or legally challenged access can make the entire process prohibitively expensive and slow.

 

Like much of what is possible in theory the theoretical 1 cm accuracy of a LIDAR scan is rarely if ever achieved in real life.

 

This is not a new technology, it's been around since the 1960's, but until now the technology to push it into the realm of useful and affordable has been lacking. That is changing and I look forward to a time when high resolution ground scans can be considered an accessible tool for many professions. Until then it is a gas to work with small areas in high definition, I only wish more clients could afford the time and money involved in high resolution LIDAR.

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Wow Clay, excellent insight and details. Thanks! With increasing availability of computing power things can only get better. I still can't believe I have two terabytes of storage sitting in front of me as I type, and it wasn't even expensive.

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That two terabyte drive will fill up faster than you can believe Steve. It's the old house rule. Given ANY size house a man will eventually overfill it with stuff. Big house... lots of stuff.

 

Memory and storage have gotten a lot cheaper. That helps a lot.

 

Processing power not so much. To get that doubling of computer power for the next step something new is going to have to come around. The traditional chip isn't getting appreciably faster. We stack processors and memory pretty deep already but that only helps - it doesn't solve the problem.

 

With everyone going to phones and tablets for their day to day computer needs there isn't much incentive for chip makers to take big leaps to new technology. It's all about lower power consumption and less heat these days.

 

LIDAR will provide new insights into the world we live in. With stuff like retina screens and bigger brighter displays the consumers are there to enjoy those insights but the production is going to be slow and expensive for the foreseeable future.

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 Big house... lots of stuff.

 

 

 More money.... More problems   :)

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