Hi

I am new to Lidar data so am still working out the post processing. When processing a recent test dataset that I acquire there are streaks in the data and sharp changes in elevation between the streaks. I have attached a screenshot showing the streaky effect. Please can someone advise where I am going wrong? Flight height 80m with 50% overlap.

Thanks in advance.

could you confirm you have elevation gaps between different streaks? i mean, if you make a cross section, after the streaks alignment, do you have "jumps" in the model or not? Because as we can see from you screenshot, i cannot recognize "model errors" but only the reflectivity index that is different between the paths. This is normal. The reflectivity index depends not only from the materia of the object the laser are hitting, but even from the angle. The laser, hitting the same object from different angles could give different reflectivity index.

Panph Posted at 1-24 23:33
could you confirm you have elevation gaps between different streaks? i mean, if you make a cross section, after the streaks alignment, do you have "jumps" in the model or not? Because as we can see from you screenshot, i cannot recognize "model errors" but only the reflectivity index that is different between the paths. This is normal. The reflectivity index depends not only from the materia of the object the laser are hitting, but even from the angle. The laser, hitting the same object from different angles could give different reflectivity index.

Hi Panph

Thank you for the response. Yes there is definitely a jump at the edge of the pass (image and profile attached). In your message, you refer to "streaks alignment", is this a post processing task.

Thanks again.

ok, the gap is here... is the elevation in feet or meters?
Anyway, in DJI terra did you use the "optimization point cloud"? the system which should align the differents paths? Or is this a raw data out of the lidar?

Are you using an nrtk network?
By adding a rinex file with the correct time range to the work data folder before processing it with Terra, i think the results can improve.

Your problem is about strip alignment, read my articles on Linked in about it. I am using Bayesmap and LAStools to fix it.

Strip Alignment and DTM generation through the estimation of the "median ground" terrain points. A methodology for DJI Zenmuse L1
https://www.linkedin.com/feed/up ... CDEFAULT%2Cfalse%29

Recovering flight lines and Strip alignment using Bayesmap. A methodology for DJI Zenmuse L1
https://www.linkedin.com/feed/up ... CDEFAULT%2Cfalse%29

Strip Alignment for LiDAR systems with Livox laser heads (MID40; Horizon and Avia) including DJI's Zenmuse L1
https://www.linkedin.com/feed/up ... CDEFAULT%2Cfalse%29