HD-MAX Echo Sounder User Guide
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Quadratic Surface fitting: An optimal fitting paraboloid will be generated
corresponding to height anomaly at multiple benchmarks based on five
starting points. Quadratic Surface fitting is subjected to stricter start counting.
If the fitting degree is too poor, it may cause elevation correction value
divergence in the working area.
(2) TGO
Elevation transformation model of Trimble TGO software include five
parameters: constant balancing, northern slope, eastern slope, the origin of
north and the origin of east.
(3) Grid fitting
Grid fitting requires to select grid file fitting to support Trimble (ggf),
HI-TARGET (zgf), Geoid99 (bin) which can be compatible with egm-9
model. Generally, grid fitting files are great in size. Thus it may require more
time for reading. The grid fitting is rarely used in China at present. If "grid
fitting" and the other four elevation fitting methods are applied
simultaneously, perform "grid fitting" prior to other fitting methods.
(4) Free Survey Height fitting
Elevation transformation model of Trimble includes five parameters: constant
HO, northern slope, eastern slope, origin latitude and original longitude.
Figure 7-13 Simulating comparison chart of elevation fitting plane
