# Hugin Control Points table

From PanoTools.org Wiki

The hugin Control Points table is an optional pop-up window listing all the control points in the project, whereas the hugin Control Points tab shows only those points joining a pair of images.

The list of points can be sorted by clicking on one of the column titles, clicking twice will reverse the sort:

- G CP#, the global (project-wide) index number of the control point pair, deleting points will renumber the list.
- Left Img., the index number of the first image in the pair (left/right has no significance except that this is the order they are shown in the hugin Control Points tab).
- Right Img., the index number of the second image in the pair.
- P CP#, the local index number (of two images shown in the Hugin Control Points tab) of the control point pair, deleting points will renumber the list.
- Alignment, the type of control point, these can be normal control points, horizontal control points, vertical control points or straight line control points.
- Distance, the distance in pixels between a perfect alignment and the actual alignment achieved by the optimiser. Otherwise, after selecting Fine-tune all Points from the Edit menu, this column shows the correlation between the points (0.0 indicates no correlation and 1.00 indicates 100% correlation) - Typically values over 0.8 show that the image areas around each point of the pair are very similar (an 80% correlation).

Selecting a row in the table will display the relevant pair of images in the hugin Control Points tab and highlight the control point in red.

Clicking delete will remove any selected points/rows from the project.

You can select more than one row by holding down the Ctrl key and picking extra rows, similarly you can select a range of rows with the Shift key.

Clicking Select by Distance allows you to select all the points depending on the value in the Distance column, eg:

- Enter 10 to select all the points with an optimiser error greater than ten pixels.
- Enter -5 to select all points with an optimiser error less than five pixels.
- Enter -0.8 to select all points with a fine-tune correlation less than 80%.

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