Set up vertical scanning in ALS

[dongdada896]

Because of some research needs, I want to try vertical scanning In ALS data simulation.But I can't find any instructions about this even in Helios++.Is there no such function? Thanks！

[kathapand]

Hi, you could adapt the scanner mounting using the rotation tag in the XML files (see description of platforms in the Helios++ beta Wiki). Probably you'd want to have -90° for the X-axis (global mode); or no rotation ("None"), depending on what the default is. If you mean something different, could you please provide more details on what the expected outcome is? If you find missing or unclear explanations in the wiki, we are also very happy about specific hints! Feel also free to get in direct contact with us (see contact details README of beta release).

[dongdada896]

Thank you for your response, and sorry for not being able to describe my outcome requirements in detail. As shown in the figure below, the box represents the scene, and the arrow lines represent the incident pulse. I hope the incident angle of each pulse is 0°, ie. scan angle rank=0°.I don't know if there are related functions. Thanks again！

[kathapand]

Thanks, got it! Since all scanners are rotating, you'd have to go for a trick, two suggestions:

1. Set "scanAngle_deg" so small, that only one pulse is emitted (nadir), nothing to the left and right. This is probably a bit "hacky".
2. Filter the result point cloud by points that were acquired with beam vectors very close to nadir (vertical). In HELIOS++ the beam vector information is in the fwf output file. So you could find the pulses there and select the respective points from the point cloud.

[dongdada896]

OK，I know you mean.I'll try second method. Thanks for your help sincerely!