Question about a result of C2C distance

[JaydenLee]

Hello
Thank you for this excellent program.
I have been studying this CloudCompare recently.

First, I have been trying to understand the result of C2C distance.
I did 2 trials with two couple of simple cloud files like below.

About this test file.
1st : Each test file has only one points.
2st : Each test file has only two points.

My question is
1. why the result is different between the below 2 trials.
2. In the below 2st, why the value was calculated like below not distance(x) = 3 like 1st trial.
( Actually, the value of distance(x) = 3 is very reasonable to me. )

Thank you for reading my question.

1st *********************************************************************************************************************************
Each file has only 1 row. and only x value is different( difference is 3 )
compared
X y z schalar
-6.09350348 -1.84549356 93.28673553 93.286736

Reference
-9.09350348 -1.84549356 93.28673553 93.286736

C2C Distance Result is below
X y z schalar distances_(Z) distances C2C distances_(X) distances_(Y)
-6.09350348 -1.84549356 93.28673553 93.286736 0.000000 3.000000 3.000000 0.000000


2st **********************************************************************************************************************************
Each file has only 2 rows. and only x value is different(the difference is 3 )

compared
X y z schalar
-6.09350348 -1.84549356 93.28673553 93.286736
-6.17963266 -1.86526489 93.28673553 93.286736

Reference
-9.09350348 -1.84549356 93.28673553 93.286736
-6.17963266 -1.86526489 93.28673553 93.286736

C2C Distance Result is below
X y z schalar distances_(Z) distances C2C distances_(X) distances_(Y)
-6.09350348 -1.84549356 93.28673553 93.286736 0.000000 0.088369 0.086129 0.019771
-6.17963266 -1.86526489 93.28673553 93.286736 0.000000 0.000000 0.000000 0.000000

I am confused why the result of distance is not "distances_(X) = 3.0" like the above 1st trial.
In the two data, only one "X" value of the first point is different with the difference 3.

Thank you.

[WargodHernandez]

This is because C2C will measure to each nearest point pair meaning the two points will both measure against the same 1 point that is near by (as opposed to the one that is 3" away)

[JaydenLee]

Hello WargodHernandez

Thank you for your reply.