Adding single control points manually and automatically

[Andrew Bruce]

When manually adding single control points in PTGui, I've noticed the following behavior.

After adding around three or more control points between a pair of overlapping images, hovering the mouse over the first image displays crosshairs on the second image indicating the predicted location of the corresponding control point. However, when I click to place the control point in the first image, PTGui automatically places the corresponding control point in the second image, and it is often a few pixels away from the predicted location indicated by the hover crosshairs.

This suggests that PTGui performs some additional calculation between displaying the predicted location and placing the final control point.

My questions are:

1. How is the predicted control point location (the hover crosshairs) calculated? For example, is it based purely on the current geometric model based on the CP location, or does it also take the optimized warp into account?
2. When PTGui automatically places the corresponding control point after I click, does it perform a local image search (for example, feature matching or correlation) around the predicted location to refine the point's position?

I'm interested in understanding what calculations are performed at each stage. Thank you.

[PTGui Support]

Hi Andrew,

The ‘ghost’ crosshair cursor is calculated by projecting the mouse position into the other inage, based on the placement of the two images in the panorama (as seen in the panorama editor).

When auto adding a second point, ptgui performs an additional fine tuning by cross correlation of the image contents.

Kind regards,

Joost Nieuwenhuijse

ptgui.com

On 29 Jul 2026, at 10:17, Andrew Bruce <abrucenati...@gmail.com> wrote:



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