HIS survey managemet: comparision

When retreiving 'final' data, one more important process is

comparing new underwater objects (rocks, wrecks, obstructions) to those already in database.

This is called conflict resolving. For wrecks the conflicts are solved using special dialogue in HIS,
for other objects automatic procedure takes place.
The procedure marks old objects as 'not visible' if they overlap with new ones (in circle with 1m radius) or do not exist in new area.
'Not visible' means that these rocks cannot be accessed through HIS, but they are still kept in table.
The aim of that is to allow access only to new and confirmed objects and get rid of duplicates.