OPUS Projects
User Instructions
and Technical Guide
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|
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At the bottom of this web page are
Processing Preferences. The defaults for these preferences are
defined
by the project manager, but can be overridden by these controls for this session processing
only. Consult with the project manager before overriding these preferences.
1.4.4.5.1
Output Reference Frame
Coordinates in the current ITRF/IGS are always included in the processing reports, but the coordinates
in an additional datum reference frame will be reported if available and selected in the drop down box.
Possibilities include
LET OPUS CHOOSE which will be the latest NAD 83 realization for the regions
covered by the North American Datum of 1983, NAD 83(2011), other prior realizations of NAD 83, and
current and legacy realizations of ITRF, IGS, and WGS84 global reference frames.
1.4.4.5.2
Output Geoid Model
Select the geoid model used to convert the adjusted ellipsoid height to an orthometric height.
Historically speaking hybrid geoid models are meant to be pared with specific realizations of NAD 83.
Possibilities include
LET OPUS CHOOSE which causes the latest NGS NSRS
hybrid geoid model, to be
used. The manager also has the option of selecting legacy hybrid geoid models, and some gravimetric
geoid models. A point of clarity is worthwhile here:
The conversion from ellipsoid heights to
orthometric heights is done as a purely algebraic removal of the geoid undulation from the ellipsoid
height. Those users familiar with “Height Modernization” should not confuse this conversion with an
actual least squares adjustment performed in the orthometric height domain.
1.4.4.5.3
GNSS
Specifies the GNSS whose data are to be used. Currently the only choice is
G (GPS-only).
1.4.4.5.4
Tropo Model
Specifies the tropo model parameterization (implementation). Two choices are available:
Piecewise
Linear or
Step-offset. Piecewise linear will instruct the program to parameterize the tropo correction as
a series of connected straight lines; step-offset as a simple series of stepped values. See Section
1.3.5.2.4.4
.
1.4.4.5.5
Tropo Interval(s)
Specifies the time interval between corrections mentioned
in Section
1.3.5.2.4.4
.
1.4.4.5.6
Elevation Cutoff (deg)
Specifies the elevation cutoff mask, in degrees above the horizon. Data from satellites below the
specified mask will be ignored. Each session processing is allowed to have a unique elevation cut off
mask based on the manager's survey plan.
1.4.4.5.7
Constraint Weights
Specify approximately how much constrained coordinates are allowed to shift in the solution. The three
choices for
Constraint Weights are:
LOOSE -allows up to one meter of float for the constrained points in the adjustment.
NORMAL -allows up to one centimeter of float for the constrained points in the adjustment.
TIGHT -allows up to one-tenth of a millimeter of float for the constrained points in the adjustment
(effectively fixing and not allowing the constrained control points to move).
1.4.4.5.8
Session Network Baseline Design
The manager may select a basic network design strategy for the baselines created during session
processing. The four
Session Network Baseline Designs are:
User Instructions and Technical Guide
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National Geodetic Survey
USER: - the design no longer conforms to one of the other strategies.
CORS: -automatically selects all included CORS, and only the CORS, as hubs.
MST: -a 'minimal spanning tree' connecting all the included marks and CORS together using the fewest
and shortest possible unique baselines.
TRI:
-included marks and CORS are connected to their neighbors forming triangles (closed loops).
1.4.5 Solution Quality Indicators
Below the map, near the bottom of the web page (Figure 1.41), is a table listing selected solution quality
values for all project marks in this session. The values are checked against the project’s solution quality
thresholds. If a value exceeds its preference threshold it is highlighted using an orange background
color and border.
In addition, the mark’s icon is changed to reflect this condition. The
Solution Quality
Indicators table in figure 1.41 shows that the processing results for this session meet the project’s
preferences with green open-circle icons and no highlighted cells.
1.4.6 Data Availability
At the bottom of the web page (Figure 1.41) is the
Data Availability table creating timeline-style
graphics indicating data availability for each mark’s data file in that session. Each cell represents a time
span and number therein is the most common number of satellites (mode) for that span. If the number
of satellites is greater than 9 (10, 11, 12, …) the cell will contain the hexadecimal representation (A, B, C,
…). The cells in the table are color-coded. White for less
than four satellites tracked, implying
processing during the indicated time span is not possible. Then yellow through dark green indicating
four or more satellites respectively.
1.5
Individual Project Mark Web Pages
Descriptions, photographs and occupation information, i.e.
metadata, and processing results for
individual project marks appear on dedicated web pages for those marks. A project manager can
navigate to these
individual mark web pages using the links provided in the
Sessions & Solutions table
(Section
1.3.6
); others can navigate to these pages using the links in the
Solution Quality Indicators
table (Section
1.4.5
) or the Data Availability table (Section
1.4.6
). These tables always appear
directly
under the map on their respective web pages. In all cases, the mark IDs that serve as row labels in these
tables are links to the corresponding project mark web page. Project members can also navigate to
individual project mark web pages using the mark ID in the pop-up bubbles that appear when a mark
icon on a map is clicked.
The individual project mark web pages have several sections and most have controls
specific to the
section. Furthermore, additional controls appear or are enabled if a mark’s web page is accessed by the
project manager.
Figure 1.52 - Project mark web page