Huge derived Point cloud from Agisoft SfM with warning Data type 22

[Rania Saleh]

Good evening,

regarding  my work i used Agisoft to get a high dense Point cloud with tie Point up to 10,000 points then i used Etrs89 utm 32 N as projection with GCP and i exported the file with laz format split 400*400 m

the Points are never classified so i know there are noise but i thought through lasground i can get the best solution 

every time i use any las_functions i get  a warning about Geokey and Data type 22 of Attribute (see warning photo)

i have no idea what those cuz i am not studying Geoinformatics.

is there a way to solve it!

second i followed an exmaples from Mr. Isenburg regarding Photogrammetry_point_processing with its Batch but the Disk with its 175 Gb was full so i couldnot run all order ,but the Original exported file from Agisoft was 13.27 Gb!

is there any way to resize file without loosing data 

third i have not undertood why there were gaps between points on Fotos only_ground and full(voll)

txt file describe the raw data 

what is the best way to generate or create DTM in Lastools from dense Cloud derived from Agisoft Metashape Pro ?

thanks 

Rania 

[Martin Isenburg]

Hello,

(1) the warnings come from the fact that the export uses the deprecated triple extra byte (type 22) to store the surface normal. You can simply ignore this warning for the purpose of your work. If interested, more on this issue here: https://github.com/ASPRSorg/LAS/issues/1#issuecomment-804394307

(2) your density is 1000 per square meter. That is a lot. If you would only use 16 points per square meter for the ground finding that should be more than enough. Using lasthin you could flag or classify the most central points of every 25cm by 25cm area as the point you use in lasground. You can always "thicken" the found ground afterwards and pull the other points that are close to the ground into the ground class using lasheight. have you read all the articles on classifying photogrammetric points?

http://rapidlasso.com/2014/06/13/dtm-from-dense-matching-points/ 

http://rapidlasso.com/2014/08/25/processing-large-dense-matching-point-clouds/ 

http://rapidlasso.com/2015/09/21/creating-dtms-from-dense-matched-points-of-uav-imagery-from-senseflys-ebee/ 

http://rapidlasso.com/2015/10/07/removing-low-noise-from-semi-global-matching-points/

http://rapidlasso.com/2016/11/22/creating-a-better-dtm-from-photogrammetic-points-by-avoiding-shadows/  

http://rapidlasso.com/2017/06/13/integrating-external-ground-points-in-forests-to-improve-dtm-from-dense-matching-photogrammetry/ 

http://rapidlasso.com/2017/07/04/removing-excessive-low-noise-from-dense-matching-point-clouds/

http://rapidlasso.com/2018/12/27/scripting-lastools-to-create-a-clean-dtm-from-noisy-photogrammetric-point-cloud/ 

http://rapidlasso.com/2019/01/02/digital-pothole-removal-clean-road-surface-from-noisy-pix4d-point-cloud/

http://rapidlasso.com/2019/04/09/using-open-lidar-to-remove-low-noise-from-photogrammetric-uav-point-clouds/
http://rapidlasso.com/2019/05/01/clean-dtm-from-agisoft-photogrammetric-points-of-urban-scene/  

(3) i see edge artifacts in your current ground classification. that tekks me you are using none or too small buffers for your tiles. Using buffers is important!

https://rapidlasso.com/2015/08/07/use-buffers-when-processing-lidar-in-tiles/

Regards,

Martin

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[Rania Saleh]

Hallo,

Thanks a lot i ll try to read those 

but is there any way to remove the huge number of Buildings those have different levels ...  is using a footprint_building shapefile through lasclip give a good solution ?
i visited the place and there are different height and also some Buildings are hidden that is why i thought footprint could give a solution

regards

Rania

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