GRUP Group of points with special weights
Columns | format | contents/explanation |
|---|---|---|
1-4 | A4 | GRUP (format-free) |
| A | First point name (inclusive) |
| A | Last point name (inclusive) |
| F | Factor for sx' and sy' |
This statement defines a range of point names by an upper and a lower limit. The photo measurements of all points with a name within this range are combined in a group with a special weight. The a priori standard deviation of these photo measurements is computed from sx' (see PARA statement) multiplied by the given factor of this group. This may be necessary if points of different precisions of definition or measurement are to be included in the bundle block adjustment. The various resulting measurement accuracies must then be considered by different factors.
The following groups for example may be formed if most of the image points are signalised points, if some are natural points and some are poorly defined points which, however, shall not be neglected during adjustment:
- Group 1 : for un-signalised points
- Group 2 : for poorly defined points.
Points not defined in a GRUP statement will not be assigned a special weight. The a priori standard deviation for image measurements defined by the PARA statement is applied for those points (equal to factor 1,0). In the above mentioned example, these would be the signalised points.
BINGO numbers the GRUP statements according to the sequence of input. One data set may contain up to three GRUP statements, so that altogether four groups can be formed.
The established ranges of point names may overlap. If a point is part of several ranges then it is included in the group which has the lowest number. (Numbering is in input sequence.)
The empirical standard deviations of the image coordinates will be multiplied by the factor of the group.
Example:
GRUP A300 B500 1.8
GRUP 150 4000 0.6
This statement allows as well definition of radial photo ranges of a camera for separate variance component estimation for each ring area. At least six values have to be indicated. This input overwrites the default radial distances which are defined as eight areas with the same number of photo measurement.
Example: GRUP 20.0 35.0 50.0 65.0 80.0 95.0 115.0