To use fisheye undistotion

[zgxsin]

Update the code to work with distortion model EQUIDISTANT

[zgxsin]

@vrabaud Could you review this MR? EQUIDISTANT distortion model is defined in image_geometry package, but not implemented. I think this is a bug. I have already used this MR for Equidistant model. It works well.

[YoshuaNava]

Dear @vrabaud and @mjcarroll,
My colleague @zgxsin has implemented the equidistant distortion model. We have internally tested this and found that it leads to lower reprojection error (measured with Kindr) when matching corner features collected from rectified images.

We would be really interested in doing anything needed to contribute this to your repo and have it on master soon. We don't want to diverge from the main development branch and miss the chance to contribute our changes to the robotics community.

Please let us know your thoughts.

Best regards,
Yoshua Nava

[mintar]

This PR can be closed, since #358 was finally merged.

[YoshuaNava]

@mintar Thank you for taking forward #358 and pushing for it to be merged, it is a really nice contribution. 🙏

[zgxsin]

This PR can be closed, since #358 was finally merged.

Thanks. Close it now.