Two sparse point numbers appearing in Show Info dialog of a Chunk

[Ryuseiken]

I'm using PhotoScan Pro 1.3.1.

When we select Show Info command from the context menu of a Chunk in Workspace pane, two values of sparse points are shown in the format: XX of YY.

For example, in the attached image, they appear as:
1,447 of 1,561

I’d like to know what these values mean. According to my guess, the number on the left is valid (not removed) number of tie points, and the number on the right is the number of tie points originally made by the feature matching process in Align Photos.

However, even immediately after Align Photos, the number in the left is already smaller than that in the right. It indicates that some quality control is applied to the original matching points in Align Photos. I also would like to know what kind of selection is done in this command.

Thank you.

[Alexey Pasumansky]

Hello Ryuseiken,

Align Photos stage is performed in three steps: feature points detection, image matching and camera alignmnet actually.

After image matching is finished, there's a set of matching points found - this is the second (bigger) number. During the camera alignment when exterior and interior orientation parameters are being estimated, some matching points may be filtered out, if they do not fit the estimated camera positions properly.

[Ryuseiken]

Thank you Alexey.
Its clear now.