A left-handed coordinate system is defined in such a way that the X-axis is pointing North/South direction and the Y-axis is pointing West/East direction. They are not commonly used but still, there are some countries using them.
Pix4D supports this type of coordinate systems and it allows the user choosing the orientation of the axis, Standard is the left-handed system whereas Modified would be right-handed.
When using the left-handed (Standard) option,Pix4D works fine but the export products (point cloud, orthoimage, DSM, DTM…) will have flipped coordinates meaning that the X coordinate will be written as the Y (with opposite sign), and the Y will be written as the X (with opposite sign).
There is no workaround at the moment except for using the Modified system.
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Regards.