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  We are busy with and Aerial mapping project  for a 10 Km upgrade of Louis Botha Avenue in Johannesburg. 

We are flying  the site on behalf of surveyors who are tasked with the detailed mapping of the route. 
FLying is being done using DJI Pahntom 4 drone – perfect tool for these narrow corridor mapping projects. The 10Km length has been split into 7 separate legs. Each leg will  be flow separately – this to ensure VLOS requirements are met.
Flying height is 80 meters above ground level, this to obtain 4cm GSD ( pixel resolution )
The orthophoto mapping  produced will be used to draft survey plans of all road markings plus service point positions in roadway. This is a considerably more efficient  and much safer solution than that trying to arrange road closures. 
JMPD provided clearances as required by Civil aviation and asked the flying be done on Sunday morning when there was minimal traffic. They did not require road closures to minimize traffic disruptions.
# UAV Drone aerial mapping 5dSurvey
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Chris Kirchhoff
Professional Land Surveyor
Tel : 082-773 4868
chris@kirchhoffsurveyors.co.za
www.kirchhoffsurveyors.co.za

For  UAV ( Drone) mapping – We are legally compliant with all Civil aviation authority, Department of transport and insurance requirements

Licence details ASL/ROC Nr. CAA/G1221D ATO # CAA/0380 in association with UAV industries.

We believe good spatial information leads to superior planning, diminished project risks, improved feasibility assessments and efficient resource utilisation.

Problems arising in using UAV ( drones ) for photogrammetric mapping.

Interestingly, more and more photogrammetry operations are acknowledging how difficult it is to obtain consistently accurate results for drone based mapping projects.

Over the last 7 years of doing aerial mapping using UAV’s ( drones ) and photogrammetric software such as Pix4d, Agisoft and opensource solutions – if the input data is not perfect the chances of processing errors’ occurring dramatically increase.

For us the 4 lessons learnt are :

The value of well positioned and well-marked Ground control points spaced no more than 300m apart.

Ground control must be placed around perimeter and in centre of project – minimum of 5 points is critical.

Enough ground truthing points should be measured across site to have reliable quality control process post data processing.

Flying the site is the simplest of the tasks involved in aerial mapping

 

This month in Point of Beginning magazine there is an article supporting how complex photogrammetry really is : to quote “ As more land surveyors use drones as part of their daily work, they are finding themselves having to learn the ropes of photogrammetry. Having done data processing for thousands of drone survey projects, we have learned the hard way why photogrammetry is a PhD-level science. We have banged our heads against every wall there is and learned some essential lessons that we now apply to every project we work on. We have explored which parts of the photogrammetry process can be automated and tested the fully-automated tools on the market.

 

In order to make sure our team has the chops they need, we rely on the American Society of Photogrammetry and Remote Sensing (ASPRS) as the only nationwide organization that provides certification for photogrammetry. Issues are common in drone photogrammetry projects — nearly half of the projects we process for customers have some sort of issue. We’ve found that having a qualified photogrammetrist involved in every drone survey is necessary to answer three critical and common questions:”  read more at

 https://www.pobonline.com/articles/101581-hard-learned-lessons-in-drone-photogrammetry?id=101581-hard-learned-lessons-in-drone-photogrammetry&ajs_uid=2127J7711801G5W&oly_enc_id=2127J7711801G5W&ajs_trait_oebid=3782E0258467B1M 

hard-learned-lessons-in-drone-photogrammetry

 A few days ago,  the Chines lunar probe landed on the far side of the moon.

This historic occasion allowed us to see the far side of the moon ( which is always pointing away from the Earth ) for the first time.

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The critical information allowing for the probe to land on the surface was provided by on board LIDAR mapping sensors.

From chines news site “At around 100 metres 3D laser scanning imaging provided elevation data, as part of a hovering phase which allowed for avoidance of hazards on the surface which could have threatened the landing.

 

The video is fascinating to watch – first the probe is flying horizontally above the surface and then as the correct position is reached the probed rotates 90 degrees and begins its descent.

https://www.youtube.com/watch?v=GwDYN5J5chA&feature=youtu.be

the web site also has an animation showing how the Lidar sensors allowed for aerials mapping and a safe manged descent onto the surface.

/heres-the-amazing-footage-of-the-change-4-landing-on-the-far-side-of-the-moon

https://static.gbtimes.com/uploads/files/2018-12/28/CAST-CE4-landing-section.gif