Horizontal Aerial LIDAR?

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Raymond
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Horizontal Aerial LIDAR?

Post by Raymond »

This question has been debated among experts. Some argue that photogrammetry can be very accurate, others claim otherwise. "For top accuracy (a must in my project) LIDAR is the way to go"

The Sixth Floor Museum in Dallas has not been very receptive to my plans to bring a laser scanner to the 6th. Floor. Its southeast corner is the infamous Sniper's Nest. A Plan "B" is needed.

I am told by a terrestrial competitor of the dronecopters that as the bird flies higher, the accuracy is lower. However, my plan is to fly the chopper within inches outside the windows. The scanner would be positioned horizontally.

See the disappointing results that I have with my current data. I received it as a donation from one of the fellow techies that worked in this program:

https://www.youtube.com/watch?v=8XWW2G3rSWM

The distinctive brick pattern is found in Floors No. 1 and No. 6:
Clear in lower floor, unclear in the upper floor.jpg
Notice the huge difference. This is the section near the scanner:

5 Side to Side.png
and this is at the higher floor:

(1c) Sniper's Nest Close Up.jpg
The Aerial LIDAR operators are VERY busy, traveling all over and expensive. I am getting a great discount from the terrestrial folks.

Does it make sense to perform a scan with the "camera" pointing horizontally, very close to the target?

TIA,

-Ramon F. Herrera
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[email protected]
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gsisman
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Re: Horizontal Aerial LIDAR?

Post by gsisman »

Raymond wrote: Wed Dec 25, 2019 9:12 pm This question has been debated among experts. Some argue that photogrammetry can be very accurate, others claim otherwise. "For top accuracy (a must in my project) LIDAR is the way to go"

The Sixth Floor Museum in Dallas has not been very receptive to my plans to bring a laser scanner to the 6th. Floor. Its southeast corner is the infamous Sniper's Nest. A Plan "B" is needed.

I am told by a terrestrial competitor of the dronecopters that as the bird flies higher, the accuracy is lower. However, my plan is to fly the chopper within inches outside the windows. The scanner would be positioned horizontally.

See the disappointing results that I have with my current data. I received it as a donation from one of the fellow techies that worked in this program:

https://www.youtube.com/watch?v=8XWW2G3rSWM

The distinctive brick pattern is found in Floors No. 1 and No. 6:

Clear in lower floor, unclear in the upper floor.jpg

Notice the huge difference. This is the section near the scanner:


5 Side to Side.png

and this is at the higher floor:


(1c) Sniper's Nest Close Up.jpg

The Aerial LIDAR operators are VERY busy, traveling all over and expensive. I am getting a great discount from the terrestrial folks.

Does it make sense to perform a scan with the "camera" pointing horizontally, very close to the target?

TIA,

-Ramon F. Herrera
JFK Numbers
[email protected]
Raymond,

I would think that just getting a static additional scan from the ground with a detail scan of that area would suffice and be a lot simpler, if it was registered into the other scans data you have. Even the 6th floor should be able to get a good detailed scan showing that detail with any upper level scanner (I'm only very familiar with the Leica Scanners, which I believe you said your donated scancloud of the area was obtained with.
From the opposite side of the street a P-series or RTC360 could easily reach that...

Dealeyplaza.PNG
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jcoco3
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Re: Horizontal Aerial LIDAR?

Post by jcoco3 »

I agree with Steve. Sounds like all you need is more resolution, and that can come from either a higher resolution scan or many scans compiled into adequate resolution. I would not bother with drone laser scanning or drone photogrammetry unless you ate trying to obtain surface deviations on each of the bricks (which I doubt you need).
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Re: Horizontal Aerial LIDAR?

Post by steves01x »

Scanning - P40 at one of the higher resolutions, either full 360 or a detail scan would pick it up.

Photogrammetry - decent 60mp body, 200mm or 400mm lens plenty photos/overlap and pump it in to AgiSoft or Capture Reality etc. Ideally if you can source it a cherry picker and a medium format camera would give you even better results. (You can hire a 50mp Canon 5DS R and 200-400mp lens for $600 ish for a week)

Depending on the importance/budget i would probably try and get someone with a Topcon Falcon 8+ or DJI with Phase One camera to fly the entire area and the elevations.

Have a look at this page for more info on the Heritage aspect of scanning / photogrammetry:

https://historicengland.org.uk/advice/t ... -heritage/
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Re: Horizontal Aerial LIDAR?

Post by Peyman Bashiri »

As others mentioned it would be a good idea to have multiple to setups with terrestrial scanner and take high resolution scans and register it to your original point clouds. I attached a pretty close scene of a heritage building I recently scanned to show you what will you have from a scan on a ground level of a 6 story building.
Feel free to be in touch if you have any question.
Peyman
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Raymond
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Re: Horizontal Aerial LIDAR?

Post by Raymond »

gsisman wrote: Thu Dec 26, 2019 2:32 am
Raymond,

I would think that just getting a static additional scan from the ground with a detail scan of that area would suffice and be a lot simpler, if it was registered into the other scans data you have. Even the 6th floor should be able to get a good detailed scan showing that detail with any upper level scanner (I'm only very familiar with the Leica Scanners, which I believe you said your donated scancloud of the area was obtained with.
From the opposite side of the street a P-series or RTC360 could easily reach that...
Here the inside scoop.

https://leica-geosystems.com/en-us/case ... -a-tragedy

At Leica Geosystems (seen in the PBS Nova program in the OP) they were very receptive at first:

[LG:] "Would you like to buy one of our scanners? They are state of the art, top quality."

[Ramon:] "No, I only need one location, one job. Do you offer such service?"

[LG:] "Of course, all over the United States"

[Ramon:] "In fact, you have already done a scanning job at that site."

[LG:] "Where is it?"

As soon as I uttered the 2 ominous words, they ceased all communication with me. It is part of my chosen endeavor. They were not the first and won't be the last to throw the door at my face. I just have to buy a football helmet.

However, a few years later the engineer who did the post-scanning work gave me a ring. I fell on my rear bottom.

[MMcC:] "The reason I am donating this to you is because you wrote in our web form that you are Not-for-Profit and Open Source. Those files cannot be used for commercial gain"

[Ramon:] "No problem, Mike"

For the first time since I have been in this endeavor, I was the one who had to hang up. My benefactor was enthusiastic, recommended some friends of him who developed software (PhotoModeler), gave me tips, free consulting, advice and above all, moral support.

"Keep up the good work, Ramon!"

I had made long term, wishful arrangements with a company that also uses Leica (I called them once in a while "some day we will do this, when I can find the money"). They lowered the price in their quote. They threw in the indoor part (6th. floor) for free. After the donation, I immediately gave them the news and the point cloud files, which are here:

http://www.dealey-plaza.org/this-govern ... /pbs-nova/

Their pronouncement:

- "Ramon, they only made 8 passes. Missed 2 walls of the main building. I went to Dallas to see the place. I would do 25-30 passes. They used the Leica P-20, we have the P-40"

https://www.truepointscanning.com/equipment-for-sale

-Ramon
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Re: Horizontal Aerial LIDAR?

Post by steves01x »

Just to add to pbashiri examples.
P40_RTC_Scan1.JPG
Both single scan / single model space. Top is P40 at 1.6mm @ 10m resoltuion. Bottom is RTC 360 on highest resolution which works out at 3mm at 65m (RTC range drops in half at highest resolution). If it was a heritage job the P40 would of been moved closer and set up higher on the telescopic tripod which would improve quality or even a detail scan at the next resolution up plus photogrammetry.

If you are getting in another scanner you really want something that is P40 or Z&F 5016 range/quality - can you not get a good deal on P40 to hire for a day? Or are we just used to really good rates / service over here in the UK!?
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