About control points

[nick_2]

Hi everyone !

I don't know the meaning of constraints when setting control points.
What's different when checking the constraint checkbox and not doing it?

Thank you in advance for your help.

[cam3d]

Good question! - I have no idea but I'm curious too!

[Andrea Alessi]

Hi Nick,

constraints will drive the reconstruction to the desired solution you set using constraints.

This is especially useful when you, say, get a sparse point cloud and you see that there are some wrongly placed cameras. You can then set control points and re-run the reconstruction/optimize camera paremeters to guide zephyr to the desired solution - and if you want the solution to also have specific coordinates (e.g. from a GPS device) you can set them as well.

Controls are what their name says - just a control. It will not be considered when reconstructing as a constraint, but will still tell you which is the residual between the computed coordinate and your expected coordinate, so that you are able to measure accuracy/errors.