Extract temporal data from Lidar data

Dear Sir/Madam,

I have around 1800 datafiles (in .mat or .pcd format) of Lidar with the filename in discontinous order (1,2,4,6,9, etc.). This Velodyne lidar data scan for a beam deflection under loading over a period of time, so my task is to determine the deflection at specific cross sections over time. I have an idea is that I will extract the coordinate of a fixed point belong to the section for the whole 1800 data file so that I can see how that point moves along the time by simply subtract the z-coordinates (for instance z1 at t = 1s minus for z0 at t = 0s). So I want to ask for a help to extract the information of a fixed point for the all 1800 files I have. Thank you for your consideration!