point cloud precission degraded during export

[JMR]

Here is what I find.
Build a dense cloud within Metashape and pick a random collection of points. (I have done by means of the point drawing tool and then exported shape layer as survey point)
what I get is a list of points with coordinates like this. I have forced 4 decimal places on purpose.

469198.0893   4625535.6525   1020.9728
469200.9825   4625551.8803   1020.9609
469216.0177   4625558.8820   1020.7016
469235.0625   4625544.2959   1020.5023
469259.3013   4625557.6343   1020.7807
469272.4699   4625569.4271   1020.6212
469253.4956   4625577.6966   1020.1291
469223.2505   4625592.8820   1020.1857
469201.0821   4625580.1614   1020.6648
469180.5939   4625594.9720   1020.4086
469200.7915   4625598.4140   1020.4623
469222.4491   4625573.0174   1020.4413
469205.2609   4625563.3425   1020.8171
469234.5305   4625580.4200   1020.2658
469238.0023   4625565.8765   1020.3454
469228.7112   4625549.2787   1020.5605
469224.8822   4625529.2167   1021.2488
469212.8580   4625520.4667   1021.3260
469235.9866   4625517.7975   1020.7513
469262.2400   4625536.9397   1020.6720
469289.2738   4625544.9382   1020.3045
469297.8275   4625565.9952   1019.9460
469290.8024   4625580.5749   1019.9231
469257.4640   4625590.1000   1020.0492
469233.1867   4625595.1511   1020.1426
469250.0749   4625603.2549   1020.0406
469212.4016   4625582.2603   1020.4655
469178.2591   4625560.1662   1018.1213
469176.1339   4625535.1855   1020.6418
469205.2949   4625525.7642   1021.1719


Then I have exported the dense cloud and open into CloudCompare and picked a similar collection (not the same ones, I said its a random sample)
Here is what I have

469212.8600   4625596.7200   1020.3900
469193.0000   4625609.5200   1020.4000
469273.4700   4625628.8600   1019.9400
469236.1300   4625634.8300   1020.1400
469365.8400   4625617.5800   1019.4100
469335.3000   4625558.8000   1020.1400
469269.9900   4625564.1500   1020.6700
469238.5000   4625556.9900   1020.4500
469196.2000   4625576.6500   1020.9900
469174.4100   4625563.3200   1020.8000
469176.0100   4625538.6600   1020.8900
469233.8900   4625493.7500   1020.5500
469287.3700   4625511.6400   1020.3300
469304.8600   4625540.0500   1020.0500
469350.1100   4625617.9000   1019.1800
469353.5000   4625662.0400   1019.3200
469205.2900   4625511.9200   1021.3300
469201.3000   4625540.5200   1021.0300
469219.8300   4625568.7100   1020.5900
469250.2700   4625592.5300   1020.0800
469282.8000   4625578.4500   1020.4100
469244.4800   4625579.8600   1020.2400
469235.8800   4625597.7900   1020.1500
469224.9600   4625581.8400   1020.3300
469193.8700   4625594.0400   1020.5600
469203.3101   4625555.5700   1020.9900
469224.1200   4625544.0600   1020.7800
469235.2500   4625526.6700   1021.0000
469273.4900   4625524.4900   1020.7700
469287.3300   4625542.0800   1020.3800

all milimetres have gone! Why?

Same happens within Global Mapper or any program, so is it maybe Metashape degrading the point cloud accuracy during export?

Regards

[olihar]

What file format and settings are you using in the export window?

[JMR]

LAS and standard settings, with no shift applied.

Regards,

[olihar]

This should give you more then 2 extra decimal places, are you sure you are importing correctly?

[Alexey Pasumansky]

Hello José,

The number of decimal digits in coordinates for the exported point cloud depend on the coordinate precision of the point cloud points. You should see this value in Show Info dialog for the point cloud. The value is based on the effective image resolution and depth maps quality.

[JMR]

Thanks Alexey: But why do I get more precission (apparently) inside Metashape when I draw or pin points on the same dense cloud. where do milimeters and sub-mm come from in this case?
Regards