Project : High precision 3D Monitoring of OKN32 crater by using Lidar data acquisition.
The 3D displacement measurements are an indispensable observation method for the supervision and monitoring of the evolution of the crater in time. Position of the OKN32 crater is : 31.773196N,5.060452E

OKN-32 is a real environment issue, it's continously grow up, more larger and more deeper.

Actually, I am looking for the équipement which can achieve this project. Our target is to generate an 3D model of the hole (crater) once a year. Thanks for any suggestion. 

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Aerial photogrammetry or LiDAR seem first options.

JAC

Thanks a lot for your replay.

 LiDAR seem first options for me, but our problem is the lines programing. The dimension of the hole is around of 150 m of radius and 120 m of deep until the water surface and all land-survey operation will be at a safety corridor of 150 m away from the limit of the hole, we can't approach the hole because it's too unstable. Do you think that drone or helicopter with LIDAR equipment can solve the issue? If it's possible, can you recommend me names of companies which offer these kind of services.

B.Yahiaoui

Dear

I agree with Mr. Cavell, any LiDAR system that can give you 4 point by sqr meter or more, will be great.

If they a have a digital camera, you will get great orthos.

Penetration in the cone will be ok, depends in it's deep.

The clue is in the fly lines programing, may be the differences of height will cause some mess.

Thanks a lot for your replay.

Effectively our problem is the lines programing. The dimension of the hole is around of 150 m of radius and 120 m of deep until the water surface. The big issue is that we can't approach the hole because it's too unstable. All land-survey operation will be at a safety corridor of 150 m away from the limit of the hole. Do you think that drone or helicopter with LIDAR equipment can solve the issue? If it's possible, can you recommend me names of companies which offer these kind of services.

B.Yahiaoui

For sure

Sorry I can't recommend no body I'm so far from there, -32°, -71°

Helicopters may be best choice.

Drone I will not recommend, to week for wind, short batt duration, too much height difference.

The Lidar system need a GPS control station, about 25 km, your people at fiel will be safe. 

Laser pulse will not be reflected on the water...

https://www.phoenixlidar.com/lidar-products/

Please check here for dron with lidar units.

Try the Leica Geomos software for deformation measurements along with several MS 60 total stations.

The dimension of the hole is around of 150 m of radius and 120 m of deep until the water surface. The big issue is that we can't approach the hole because it's too unstable. All land-survey operation will be at a safety corridor of 150 m away from the limit of the hole.

Riegl has a drone solution equipped with ultra lightweight LIDAR (RiCopter and VUX-Sys).

RiCopter can fly for 20-30 minutes with 20-30 km/h speed, which means about 10 km, it must be enough.

The only problem is the price. The whole system is more than 300k USD.

If there is no strong wind is blowing, I would use a medium class drone (e.g. DJI Phantom III for 2k USD, or Phantom 4 for 5k USD) as the cheapest solution, depends on the accuracy expectations. Phantom 4 has better camera, better resolution.

After doing overlapping vertical axis photos about the crater, you can process the photos with a simple photogrammetric sw., such as Agisoft Photoscan Pro (about 3k USD). Agisoft can automatically process orthophotos, surface model, etc., which you can export to AutoCAD, or even pointcloud format such as LAS.

If you need real measurements on the model (not only for visualization), you must deploy and measure some control points surrounding the crater (4 GCPs - Ground Control Points - are enough, the more you deploy the higher accuracy you can achieve). Easier way is to place a sheet of paper onto the surface (fix them to ground with spikes) and measure the center of the paper with RTK GPS before the flight. You don't need to go too close to the crater, GCPs can be on the outer area which will be covered by the aerial photos. The necessary flight altitude and the overlap is depends on the accuracy you need.

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