Abstract: This project was executed by SBL for a mining company having operations in Africa. The study area covered approximately 32 sq.km of land falling in the south western part of Congo.This project was awarded to SBL based on the excellent quality and timeliness shown during an earlier project for Landuse and Landcover mapping. The client requirement was for the creation of hight accuracy DTM editedto 0.2m, DSM of 0.2m and orthophotos of 10cm GSD using UAV imagery

Client: Client is a mining company based in the UK and having mining operations in various parts of African continent

Geography: ~32 sq.km of land falling in the south western part of Congo

Industry: Mining .

• GCP distribution was not even and so getting a good quality stereo model became difficult. So SBL’s experts suggested suitable areas for collecting additional GCP’s which proved to be very useful in the end.
• Fixing the terrain height and water body was a challenge as the area is a dense forest with large swathes of swampy land.
• Data being of 0.2m handling and viewing it was difficult.
• Editing 0.2m DTM was a very big challenge.

Approach: SBL used state of the art UAV softwares in carrying out the Aerial Triangulation of the UAV images. After Point cloud densification and DSM creation Undistorted images were generated by the UAV software after the creation of DSM data. The Aerial Triangulation reports were imported into Inpho Match AT and stereo models were created in it. After this DTM were generated and edited using Inpho DT Master software. SBL’s highly experienced professionals produced high accuracy DTM by the correct usage of soft and hard breaklines . All manmade structures and vegetated areas were interpolated to terrain height after plotting breaklines which were fixed to terrain heights. The edited DTM points were exported in XYZ format and edge matched with adjacent DTM tiles and dispatched to the client.

Benefits: The client benefited by this work in
• Getting high accuracy DTM’s of 0.2m by the use of cutting edge UAV softwares.
• Very quick turnaround time.
• Use of photogrammetry software along with UAV software helped in getting a good DTM output.

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  • dear mr. Jegan, how to generate dsm file to dtm use las data? please and advices

  • Contact me at jeganam@gmail.com

  • Hi Martin
    I know that almost all the UAV softwares are capable of producing DEM/DSM automatically and can also produce good orthophotos from them. What I am talking about is that we did DTM editing using classical photogrammetry methods by doing the DTM in Inpho DT Master. We used the results from Pix4UAV and created stereo models from them in Inpho Match AT.From this DEM were generated and DTM edited in Inpho DT Master. This I believe is special considering the fact that most UAV processing softwares do not provide DTM's.



  • Moderator

    Sorry to hear that Jegan hope he gets well soon perhaps you could drop a picture of the aircraft and setup into this thread.

  • Dear all,

    I could not reply because my son was in hospital. iT really pains me to see people jumping to conclusions and saying whatever they like.

    We used Pix4 UAV  ver.2.2 for this project. We used the result from Pix4UAV and imported it to Inpho Match AT. This helped us to create DEM which was edited to produce DTM output. you cannot produce DTM straight away from Pix4D . We used total of 32 GCP s which were well distributed.

    Total 20 mission flown having good overlap and camera was CanonIXUS125HS.



  • This is nice, but what is the absolute precision? 0.2 m GSD is one thing, but what is the RMS on the check points? You did not say anything about the UAV, if it was <10kg UAV and you used indirect orientation approach or big UAV with GPS/INS system for direct georeferencing and thus classical airborne photogrammetry processing pipeline. If it is the first case, I really doubt that you have done anything special (no offence) which you could not do with other services (Pix4D, Aerogis etc.)

  • Hi Martin & marcelo,

    You may correct,

    but the true behind this you can get 0.2 m DTM (Digital terrain modelling) using Inpho Match AT software,

    I have more than 9 years experience in DTM & DSM.

    I am sure you cannot get this much quality DTM output form any other software or technology?



  • Yes, exactly, Martin.

    Just following posted images, they are from this company:


  • Exactly what I expected-no answers, just an advertisement for a processing service. Nothing special so far...

  • Jegan,

    What was the tested RMSE? You said the accuracy was 0.2 meters but that sounds like its your GSD not your accuracy?


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