Least Squares Tips
Posted by Jason Poitras on 05 September 2007 03:59 PM
Q. I am running a Least Squares Adjustment (LSA) with MicroSurvey 2002 (CAD or Express). Everything appears to be computing but when I view the results, nothing has changed. All the observations have residuals of 0 and the coordinates of every point are unchanged. Have I done something wrong? A. There is an important detail in the setup for doing an LSA that you may have missed. Under the subheading Important Notes: in the Help file, there is the following: - You need to eliminate the unique closing point numbers that are used for the traditional traverse balancing routines from your traverse files! For example, if you have a traverse that closes on to point 2 using point # 12, the shot number 12 must be renumbered to 2. We recommend you do this prior to coordinating your traverse to avoid computing extra points in your file. Compute the coordinates with Point Protection toggled on to avoid accidental re-coordination of point 2. TIP! In many cases, you could add the points you wish to hold fixed to the Protected Points List (found under MicroSurvey-> Coordinate Point Utilities) prior to coordinating your traverse. This will eliminate the danger of accidentally displacing them when you re-coordinate a traverse that is to be adjusted using the LSA program. When you run the LSA program, protected points will automatically be set as fixed.
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