HesaiFileReader firetime correction implementation

Hello,

I'm working with processing LiDAR data from a Hesai Lidar. When you receive the lidars, you are pointed to download both an angle correction and firetime correction .csv file. In the HesaiFileReader function you can point to the angular correction csv, but not the firetime correction csv. My main question is if the HesaiFileReader already has this firetime correction built in or if I will need to implement this correction.

Thanks

Answer 1

[Shishir Reddy]

Hi James

The 'HesaiFileReader' function in MATLAB supports specifying an angle correction through a CSV file, but it does not automatically apply the firetime correction. If precise timing is important in your application then the firetime offsets has to be applied manually.

Kindly refer the following steps to get an overview of the manual handling of firetime correction -

1. Loading the Firetime Correction Table

firetimeTable = readtable('firetime_correction.csv');

2. Reading the point cloud data using 'HesaiFileReader'

reader = HesaiFileReader('your_file.pcap', 'CorrectionsFile', 'angle_correction.csv');
ptCloud = readFrame(reader, 1);

3. Applying the Firetime Correction:

% Pseudocode
for each point in point cloud
    channel = getChannel(point);
    timeOffset = firetimeTable.TimeOffset(channel);
    correctedTimestamp = originalTimestamp + timeOffset * 1e-9; % Convert ns to seconds
end

For more information regarding 'readFrame' function, kindly refer the following documentation - https://www.mathworks.com/help/vision/ref/velodynefilereader.readframe.html

I hope this helps.