Add option to scale a-priori standard deviations for non-GNSS measurements

[rogerfraser]

DynAdjust currently permits the scaling of GNSS variance matrices by a variance factor (or the a-posteriori sigma zero calculated from a least squares adjustment). See sections 3.3.3 and 7.3.2.1 in the DynAdjust User's Guide for more information.

A new option to permit the scaling of non-GNSS measurements (i.e. distances, heights, etc.) is required.

Note - it is not theoretically legitimate to scale a-priori variance matrices comprised of variances for different measurement types (and hence, different units - metres, radians). For this reason, consideration should be given to alerting the user that less-than-optimal results will be produced when attempting to scale the a-priori variance matrix for a network comprised of different measurement types.

[sfull]

See attached for a set of basic XSL Transformations that can be applied to a measurement file to alter the standard deviations of some terrestrial measurement types.

As pointed out by @rogerfraser , this is not entirely rigorous, but it does have practical utility if used with care (e.g. on measurements made by the same instrument). Here are some situations where the XSL transformations have proven useful:

• Directions / Angles (D, A, V Types) observed in rounds by robotic total stations. The StdDev are overoptimistic. You can overwrite the StdDev with the instrument rating (e.g. 3") or other value.
• Short distance levelling, to imposed a "minimum" StdDev value
• Scaling terrestrial measurements of one type up/down whilst leaving others unaffected (i.e. avoid sigm-zero scaling of entire network).

I wouldn't consider these XSL Transformations the enhancement, but they can provide a workaround in the meantime. They can also be used as template for adding other XSL Transformations for simple measurement types.

You can see a video of how to apply the XSL Transformations (in Notepad++) here:

DynAdjust_XSL_Transformations.zip