STAR*NET V6 - Circe

Chapter 5 Preparing Input Data
5.9 Entering 2D Data in a 3D Adjustment
As discussed in the previous section, STAR*NET allows you to enter 3D data into a 2D
adjustment. The program simply reduces the 3D data down to 2D in that case. Entering
2D data into a 3D adjustment, however, is a much different situation.
For a 3D adjustment to work, 3D coordinates must be either present or computable for
all connected stations in the network! So, for any station in a 3D adjustment whose
elevation is not fixed, there must be some 3D observation data present that will cause its
elevation to be computed during the adjustment process. Therefore, 2D data of any kind
may be entered into a 3D adjustment as long as elevations for all referenced network
points are determinable in some fashion.
When your Adjustment Type in the Project Options/Adjustment dialog is set to 3D, the
program by default expects data in 3D format. However, to instruct the program to read
data entered in a 2D format, you must precede any group of 2D data lines with the “.2D”
inline code. If you switch back to 3D data lines, precede those lines with the “.3D” inline
option to tell the program what to expect.
The following data prepared for a 3D adjustment includes a section of 2D formatted data
lines. Note that stations “45” and “46” have no other observations entered which will
establish their elevations! For this data to actually solve in a 3D adjustment, either fixed
elevations for these two points must be entered, or additional observations must be
entered to define their elevations.
#Entering 2D data in with a 3D adjustment
#
C 1 12135.223 13111.435 1000.0 ! ! !
C 2 13324.665 15245.223 1299.9 ! ! !
M 2-1-3 134-45-12 2244.348 91-22-54 5.1/5.2
M 3-1-4 144-12-56 3324.222 89-56-54 5.3/5.0
.2D #Change to 2D data format
M 3-2-45 287-44-53 2554.242
M 5-4-46 166-55-34 5554.771
SS 5-4-88 76-45-22 943.342
.3D #Change back to 3D data format
M 5-4-7 172-21-47 4437.993 90-55-32 5.6/5.2
M 5-4-23 98-23-11 3255.445 90-45-51 5.6/5.7
Sample Data using “.2D” and “.3D” Inline Options
Note that “SS” sideshot data can be freely entered in a 3D adjustment in 2D format (or
reduced from 3D to 2D format using the “.3REDUCE” inline). Sideshot points are
computed after the adjustment is completed. An elevation value of “-99999” is published
for any sideshot whose elevation is not determined.
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