How is best fit ellipse drawn to a rusty hole seen at an angle in a photo?

I have a circle on a photo which is at an angle to view so its an elipse, its a rusty drill hole as such.
I need to draw an elipse to this hole, I see circle to fit points but no elipse to fit points command.

In Photogrammetry we can draw around an elipse in the same circumstances, actually seeing the draw line evolve, and its clever becoming a steady unshaky curve as one progresses and then tell the prog in properties thats its a circle, the trace alters to be a best fit, essential when creating holes from registering 3 or more photos together. Sometimes the result in the 3D window looks unstable so tweaking the trace to get a better elipse sorts it out.

What is best method to draw this hole as a perfect elipse so as to establish hole centre etc ?


snap00 3-7-2021

  1. Draw a rectangular box around the hole and adjust sides to clip what you believe to be the true edge of the hole. That gives you the centre of your ellipse.

  2. Draw a circle from the centre of the box, just clipping the hole. Use Line from Midpoint to draw a line out from the centre of the box, slightly larger than the circle and without releasing the mouse button, rotate it around the circle until you judge it to align with the true point where the circle touches the edge of the hole. That gives the major axis.

Draw the ellipse, using the major axis and making the minor axis fit the true edge of the hole.


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agree take the tool shown and raw a box if hole is an easy upright angle view aft to it, but when on a curved surface and with perspective making the nearer part of the box larger than thef arthest part of the box, especially if a hole is large, then its not easy to draw the box.

See attached, where establishing perspective is not easy, also photo taken with a wide angle camera mobile phone thing., and on a curving surface.


I’ve probably made this a little too small, but it’s a rush job.

The important point is that if this is all the data you have there is no solution that will give you a better outcome than your best guess at where the edge is.

Well, the best guess in the final analysis is probably based on knowledge of the era of the part, the standard parts system most likely used and the dimensions of the various members of the standard parts family. The approximate size determined from the photo will most likely only match closely with one of the standard part sizes. Then the only real piece of guesswork left is “where’s the %#$@&*! center”?

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Since this is about recovering historical artifacts, perhaps undigging the following is relevant?

Then again, the tooth of time has taken its toll on that one and all attachments are lost…