Automatic Mark Adjustment

Automatic mark adjustment is mainly for digitizing surfaces. In some cases, the auto-marking may not work well. This usually happens when the shape of the surface is very irregular. In this situation, mark adjustment provides an alternative solution.

Similar to auto-detection, mark-adjustment requires that feature points resemble each other in an image. Users start by selecting one point as the reference mark. The mark-adjustment feature tries to adjust the location of other marks so that they match the position of the reference mark.

Using mark-adjustment is similar to auto-detection. The Adjust subpage in the Mark page of the Main Window is designed for this purpose:

  1. Select working image and marks to be adjusted: Select the marks (turn green) that you want to adjust in the working image.
  2. Select a current point as the reference mark: The mark of the current point in the working image will be used as a mask to reposition all the other marks. Use the MagGlass to ensure that the position of the current point is accurate.
  3. Set parameters: They are similar to the those used in mark-detection.
  4. Press the "Adjust selected mark" button: Photo4D repositions the selected marks.
As marks are repositioned, they become un-selected. Marks that Photo4D fails to adjust will remain selected. Users may select a new current point as the reference mark and try to auto-adjust them again, or edit their location manually.

In auto-adjustment, the current point is selected as a "typical" point in the working image. The position of its mark will be will be used as a mask for repositioning all other selected marks in the image.

Photo4D searches in a range that is centered around each mark for a position that matches the current point mark. The size of the range is determined by the value in the Search range field. The mark will move to the position with the highest similarity score. The highest score means that the related position closely matches the position of the current point.

If the score is lower than the threshold, this mark remains at its present location and does not move. Otherwise, it will be adjusted.

Note

The following describes a scenario where mark-adjustment can be useful. First, one image is marked either manually or with auto-detection. Now suppose the surface is irregular and auto-marking cannot correctly find corresponding points in the other images. In this case, mark traversal introduced in the previous Chapter can be used to manually mark the matching points in another image. The manual marking can be done quickly without worrying too much about accuracy. Later, the mark- adjustment can be invoked to adjust marks to their accurate location.