iGage iG4, Руководство пользователя

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Z: 4585410.516(m) 0.005(m) 4585410.529(m) 0.005(m)
LAT: 46 15 35.23578 0.005(m) 46 15 35.25052 0.005(m)
E LON: 240 22 8.47069 0.002(m) 240 22 8.40767 0.002(m)
W LON: 119 37 51.52931 0.002(m) 119 37 51.59233 0.002(m)
EL HGT: 208.861(m) 0.003(m) 208.444(m) 0.003(m)
ORTHO HGT: 230.163(m) 0.018(m) [NAVD88 (Computed using GEOID12A)]
UTM COORDINATES STATE PLANE COORDINATES
UTM (Zone 11) SPC (4602 WA S)
Northing (Y) [meters] 5126276.950 103343.987
Easting (X) [meters] 297235.684 566995.383
Convergence [degrees] -1.90148112 0.63125220
Point Scale 1.00010542 0.99993063
Combined Factor 1.00007268 0.99989789
The most important indicators of the quality of an OPUS solution are highlighted in yellow.
Here are some general rules to help judge the quality of a solution:
> 90% observations used or > 80% # Fixed Ambiguities
> 50% Fixed Ambiguities or > 95% observations used
Overall RMS < 0.030(m)
Both Lat and Lon Peak-to-Peak < 0.030(m)
Ellipsoid Height Peak-to-Peak < 0.040(m)
If you collect data under canopy or in an area where there are buildings or trees that obstruct the
view above 10° elevation, the number of observations used will be lower.
Make sure you use the left-hand column (NAD_83) results, not the right-hand column (IGS08) unless
you know you want IG8 framed results.
Be careful with heights. Both ellipsoid and orthometric heights are listed. The orthometric height is
NAVD88 GPS derived and typically is the elevation you need.
The Peak-to-Peak error estimate for the orthometric height includes the error estimate for the
GEOID in addition to the Peak-to-Peak error estimate value for the ellipsoid height.
IMPORTANT: The state plane coordinates are listed at the bottom in the right-hand column. They
are in Meters. If you need Feet, you can convert them, however be careful to convert to
International Feet or U.S. Survey Feet as required by your State and application:
US Survey Feet = Meters * (3937/1200)
International Feet = Meters / 0.3048
The misapplication of Ft/M scale factor can result in a 30 foot coordinate blunder! If you request an
‘Extended Format’ OPUS results, the state plane coordinates are computed and returned at the
bottom of the report in the nominal foot type for the area .
If your survey is at a significant elevation (> 100 feet) you may need to apply the Combined Factor
(listed on the OPUS report for both UTM and State Plane Coordinates) to inversed distances to
match optical shots made at ground level.
Getting ready to use OPUS
OPUS is a great tool for grounding your survey. But OPUS is part of a larger toolset. Before you begin
a project take a moment to think about the ‘Big Picture’:
A. What are your GOALS?
a. Required accuracy
b. Horizontal and Vertical Datum; Geoid model choice
c. Survey style: OPUS-Static, OPUS-Rapid Static, OPUS-Projects
d. Consider FGDC Standards:
http://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy