Yayhoo! Employing Kent's method using the Covariance Matrices, I computed standard errors for 4 OPUS points in an 8 sided traverse, applied them to the OPUS SPCs entered as control points in SurvNet and got this--
"Statistics
==========
Solution converged in 2 iterations
Degrees of freedom:8
Reference variance:1.13
Standard error unit Weight: +/-1.06
Passed the Chi-Square test at the 95.00 significance level
2.180 <= 9.028 <= 17.535"
and, "all connection combinations passed" the ALTA tolerance test.
--which thrills me. Interestingly, the s.e.'s I computed from the matrices were very close to those I had originally assigned by the seat of my pants. I guess now I've gotta git me some o' them GPS receivers....
So, thanks all for the help, and a special thanks to the kind soul at admin who re-categorized my post for me - I never said I wasn't a dumba$$.....
SS
> Yayhoo! Employing Kent's method using the Covariance Matrices, I computed standard errors for 4 OPUS points in an 8 sided traverse, applied them to the OPUS SPCs entered as control points in SurvNet and got this--
>
> "Statistics
> ==========
>
> Solution converged in 2 iterations
> Degrees of freedom:8
> Reference variance:1.13
> Standard error unit Weight: +/-1.06
> Passed the Chi-Square test at the 95.00 significance level
> 2.180 <= 9.028 <= 17.535"
It sounds as if you've been using SurvNet to adjust conventional traverses, so you probably already have fairly realistic values for the standard errors of angles (horiz. and vert.) and distances measured with your total station, as well as for the centering errors of targets and instrument.
If not, you'll want to examine the residuals of the conventional measurements and GPS-derived coordinates separately. I'm unfamiliar with SurvNet, but assume that it gives a separate statistical summary for the various types of observations.
Yes, I've got a pretty good handle on the terrestrial aspects - just want to add some redundancy by (properly) incorporating some extra-terrestrial data. I have no experience of Star-Net, but Carlson does a good job of pointing out when one's standard errors might be somewhat optimistic and where to look for blunders.
Thanks,
SS
> I have no experience of Star-Net, but Carlson does a good job of pointing out when one's standard errors might be somewhat optimistic and where to look for blunders.
The other obvious thing to do is to set up the input file, if the Carlson software allows it, so that the network can be run using just the conventional observations and then the GPS-derived coordinates and their standard errors can be added to the adjustment after verifying the conventional observations are free of blunders and are realistically weighted.
