Support Website Contact Support Blog

Elevation in Manual Tie Points

I process mainly imagery of vegetation only, often with sparse canopies or tall grasses. Often the X,Y values of my Manual Tie Points lie on the ground under the canopy of trees for many of the images. I therefore do not select points (make a yellow circle) in those images, but I am concerned that the height of the canopy (Z value of the green circle location) may be considered in calculating the optimized elevation. I would prefer to be able to tell the software not to use that image at all just for that specific MTP optimization. Is this a valid concern, and if so, would this be a possible option in future?

had the same question - if one could “exclude” an image for that process here (or if it doesn’t make sense to do so). 

Hey Swampy, I don’t think the image with the green circle is taken into account when calculating the position of a manual tie point. Only the pictures that you mark the tie point in will be used. The green circle is where Pix4D thinks the position of the tie point would be based on the pictures you’ve already marked with a yellow circle. That way you can make sure the camera is positioned and oriented correctly.

EDIT: Here’s something from their page about manual tie points

  • The clicked position appears with a  yellow cross and circle. The size of the yellow circle indicates the zoom level with which the marking has been done. Points that have been marked on a high zoom level are taken more into account than points that have been marked on a low zoom level.
  • After clicking on 2 images, a green cross appears on all images. The  green cross  represents the reprojection of the estimated 3D point on all images, and is calculated (after having marked 2 images) according to the clicks already made for the Manual Tie Point.

It’s about half way down at https://support.pix4d.com/hc/en-us/articles/202560349