Dear Professor Delgado,
Thank you very much for your detailed advice.
Following your suggestions, I solved the issue in the following steps:
1. convert the las file from WGS84 (EPSG 4326) format to EPSG 3414 (as the lidar scan was conducted in Singapore) using las2las:
las2las64 -i cloud.las -target_epsg 3414 -o output_3414.las
2. extract information from the las file as csv file for attributes xyz, RGB, intensity (i) num of returns (nr), and num of this return (ntr):
las2txt64 -i output_3414.las -o output_3414.csv -parse xyzRGBinrc -sep comma
After reading the CSV file as a Pandas DataFrame, it seems the XYZ coordinates are in value ranges for a cartesian coordinate system:
And, the points as visualized in 3D scatter plot using the XYZ coordinates seems to be correct, or reasonable at least, now:
The first 500k points:
The full data set of 140M+ points, sub-sampled every 300 points:
Thank you very much, again, for your patience to illuminate a newbie like me.
I've learned a lot from your reply, and please allow me to take some more time to digest all the information.
Best regards
- Joe