|The SDL Component Suite is an industry leading collection of components supporting scientific and engineering computing. Please visit the SDL Web site for more information....|
|Home GeoPack GeoMap Class TGeoMap Methods CalibQuality|
|See also: CalibModel, Calibration of Maps|
TGeoMap uses a universal calibration model which is based on (biquadratic) regression. This model is better suited to situations where maps are distorted (e.g. due to scanning, or due to misalignment of individual map parts, or inaccurate reference points). In order to have a measure for the calibration quality you can use the method CalibQuality, which returns the quality numbers QualX and QualY both for horizontal and vertical directions. For an ideal map both QualX and QualY have to be zero.
The quality of a calibration can be determined by transforming the longitude/latitude information of the reference points into pixel coordinates. These calculated pixel coordinates should ideally be the same as the corresponding reference pixel coordinates. Thus the differences for a perfectly calibrated map should be zero for all calibration points. The quality figures QualX and QualY specify the average difference between actual and calculated pixel positions for all calibration points.