Set up the initial algorithm parameters (often leaving the default values is correct):
• The parameters that control how items are matched are in the second section of the dialog. The Search Distance defines how far apart the intersection of the light ray from one marked point and the light ray from another marked point can be before the points are determined to be mismatching. This threshold value is automatically filled in as the largest tightness value any current point in the project has. This is directly related to the search distance so this is often a good match. In some poorly oriented projects with sparse points you may need to increase this distance to get any items to match and in poorly oriented projects with dense point or silhouette sets you may need to decrease this value to reduce mismatches.
• The ’search distance doubling iterations’ setting is used to find additional matches, and ensure initially found matches at the search distance are reliable.
• The ‘residual threshold’ is used to limit matches to those that result in a marking residual of less than the threshold.
• We suggest that you do not ask for fewer than 3 photo references except in projects with strong geometry and sparse points or silhouettes. Two photo references are very ambiguous and it is very easy for the algorithm to misreference items that appear only on two photos. Note that this is different than the two-photograph-referencing described below when there are only two oriented photographs in the project.
• The ‘Allow coded targets…’ setting will allow coded targets to be used when auto-referencing. If a potential match is found and the point was marked as a coded target and is the only instance of that target ID, its ID will be overridden with the matched point ID.