Different Files for Same Lidar Data

[Han]

I couldn't find anything about this on the forums already so I apologise if there is and I just missed it.

I didn't spot this at first when I originally downloaded the data, but recently whilst checking some other stuff in their folders I noticed that for some courses I seem to have two versions of the .LAZ file for each "section" of the area.

The differences between them at first glance appears to be part of the name which is either "CIR" or "COL", and also the size of the file. 

Examples :







I have done some testing creating plots using these files in the following way:

1. All of them together - both CIR and COL.
2. Just CIR
3. Just COL

So far the only difference I can see is just the overall data size of the .course file once exported (which does affect how full the plant meter starts at), with the combined file version being the largest. Other than that I am struggling to notice any changes to the terrain at all when looking at the plots in the designer.

I have done some online searching about "CIR" and "COL" but haven't really found anything up to now. Anyone have any ideas ?

*Edit

I just realised while checking some other folders after I made this post that it is just the data from Spain that has these two versions of the files so I went back into the site I get the Spanish Lidar from and re-did the process for one of the areas I already have up until the point of downloading.
One other difference between the name of files that shows on the site but not once downloaded is the CIR files have (IRC) and the COL have (RGB).

[chadgolf]

Looks like the CIR is just the infrared laser color - so black and white.

The COL has been colored with either satellite or airplane data. Not any use to you.

I would recommend just using the CIR and not the COL.

The reason why using both produces bigger course files is that they are probably very similar but the points probably don't line up exactly. So the tool thinks there's more points than there really are but the second set is made up and not entirely consistent with the first.