3d best fit alignment problem

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • 3d best fit alignment problem

    I want to do a 3d best fit alignment using 8 constructed points I manually inputted with no CAD and no existing axis system in place. 4 are nominal values and 4 are actual values previously taken. When I try new alignment and best fit, select the 8 points, 3 Dimensional, Least Squares, weight of 1.000 to all, the result is no rotation or translation. Prior to trying best fit, the largest 3d deviation from a nominal point and it's actual partner is approximately .023". After best fit, I'm hoping to see an almost equal 3d deviation between each nominal and partner. What am I doing wrong? Thanks for any help.

  • #2
    Did you allow any rotation/translation in the 3D-alignment or not?
    PC-DMIS CAD++ 2o22.1 SP2

    Comment


    • #3
      in addition to vpt.se's suggestion, for 3D aln you may wish to use vector instead of least squares.

      Comment


      • #4
        Originally posted by zox20 View Post
        Prior to trying best fit, the largest 3d deviation from a nominal point and it's actual partner is approximately .023". After best fit, I'm hoping to see an almost equal 3d deviation between each nominal and partner. What am I doing wrong?
        As far as the best-fit not fitting - it sounds like you only have 4 points, but you have entered the nominals into 4 point features, and the actual into 4 other point features. This creates 8 points with no measured deviation, so there is no deviation to fit. You should create 4 generic point features. Enter the nominals into the THEO line and the measured into the ACTL line. This will give you 4 points with measured deviation. Then the best fit will fit.
        Last edited by DJAMS; 08-05-2012, 09:49 AM.

        Comment


        • #5
          Thanks for the help. I did allow rotation and translation. DJAMs got me thinking. Edit the 4 constructed points of actual values and plug in their nominal values into their theoreticals. Then best fit again only using the 4 edited actual points. Now when I open the alignment to see the values, I have something other than zero. I'll verify the deviation lengths tomorrow at work. Thank you.

          Comment

          Related Topics

          Collapse

          Working...
          X