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Sample Extract file

Format

Following this first line in an Extract file, the observation records are formatted in columns as follows …

Field # Columns
('Standard' format only) 		Data item
1 1 - 6 Instrument station
2 7 - 12 Reference object
3 13 - 18 Observed point
4 19 - 29 Horizontal angle
5 31 - 40 Horizontal distance
6 42 One-way ('*') or duplicate ('+') flag
7 44 - 53 Height difference / vertical distance component
8 55 - 64 Pre-determined height of observed point
9 66 - 81 Point code/description
10 83 - 87 Angle standard deviation
11 89 - 93 Centring standard deviation
12 95 - 99 Distance constant
13 101 - 105 Distance parts-per-million (PPM)
14 107 - 111 Standard deviation for levelling / trig. heighting
15 113 - 115 Levelling setups / bays



Examples

   Inst   
Stn 		    RO         To        Horiz.Angle        Horiz.Dist      F      Ht.Diff/VC           Height          Code/Description       Angle 
Sdev 		  Centr  Dist
  Const  		Dist
  PPM    		  Level  
Sdev 		  Level  
Bays 

     |   1 |     | 2         3         4| |      5   |     6    |    7         8 |     | 9   |     0     |   1 | 
12345|78901|34567|90123456789|1234567890|2|4567890123|5678901234|6789012345678901|34567|90123|56789|12345|78901|345
     |     |     |           |          | |          |          |                |     |     |     |     |     |

Sokkia SDR file : W867C02.e01, 24-Nov-2000 14:38:56  - SDR Job : W867-001B - Mean obs: Y; Curv/Refr: N; Sph.dists: N
    2     1     1    0.000000                                    PIN 102           10.0 0.003            
    2     1     3   78.372251   1560.825       45.554            S3                10.0 0.003 0.005   5.0 0.005  21
    3     2     2    0.000000   1560.825 +    -45.554            PIN 46            10.0 0.003 0.005   5.0 0.005  
    3     2     4  322.225999    763.154       -0.147            S4                10.0 0.003 0.005   5.0 0.005  10
    4     3     3    0.000000    763.154 +      0.147            S3                10.0 0.003 0.005   5.0 0.005  
    4     3     5   68.204751    147.504        0.075            S5                10.0 0.003 0.005   5.0 0.005   2
    5     4     4    0.000000    147.504 +     -0.075            S4                10.0 0.003 0.005   5.0 0.005  
    5     4     6  162.023498     90.454      -18.205            S6                10.0 0.003 0.005   5.0 0.005   1
    6     5     5    0.000000     90.454 +     18.205            S5                10.0 0.003 0.005   5.0 0.005  
    6     5     7  178.211501     91.737      -16.798            S7                10.0 0.003 0.005   5.0 0.005   2
    7     6     6    0.000000     91.737 +     16.798            S6                10.0 0.003 0.005   5.0 0.005  
    7     6     8  179.560874    118.382       -5.230            S8                10.0 0.003 0.005   5.0 0.005   2
    8     7     7    0.000000    118.382 +      5.230            S7                10.0 0.003 0.005   5.0 0.005  
    8     7     9  179.495502    345.149       -1.212            S9                10.0 0.003 0.005   5.0 0.005   5
    9     8     8    0.000000    345.149 +      1.212            S8                10.0 0.003 0.005   5.0 0.005  
    9     8    10  180.035666    816.532        0.294            S10               10.0 0.003 0.005   5.0 0.005  11
   10     9     9    0.000000    816.532 +     -0.294            S9                10.0 0.003 0.005   5.0 0.005  
   10     9    11  182.135750    138.726        4.803            S11               10.0 0.003 0.005   5.0 0.005   2
   10     9    13   74.314750    246.063      -10.074            S13               10.0 0.003 0.005   5.0 0.005   3
   13    10    10    0.000000    246.063 +     10.074            S10               10.0 0.003 0.005   5.0 0.005  
   13    10    14  158.124165     71.740       -3.191            PIN 47            10.0 0.003 0.005   5.0 0.005   1
; (Comment line)
   14    13    13    0.000000     71.740 +      3.191            S13               10.0 0.003 0.005   5.0 0.005  
   14    13    15  116.000500    204.946       -1.070            S15               10.0 0.003 0.005   5.0 0.005   3
   15    14    14    0.000000    204.946 +      1.070            S14               10.0 0.003 0.005   5.0 0.005  
   15    14    16  201.311250    290.101        0.123            S16               10.0 0.003 0.005   5.0 0.005   4
   16    15    15    0.000000    290.101 +     -0.123            S15               10.0 0.003 0.005   5.0 0.005  
   16    15    17  193.472000    162.183       -0.044            HR244             10.0 0.003 0.005   5.0 0.005   3
   17    16    16    0.000000    162.183 +      0.044            S16               10.0 0.003 0.005   5.0 0.005  
   17    16    18  180.002999    203.768        2.146            S18               10.0 0.003 0.005   5.0 0.005   3
   18    17    17    0.000000    203.768 +     -2.146            S17               10.0 0.003 0.005   5.0 0.005  
   18    17    19   62.245836    129.937       -0.018            S19               10.0 0.003 0.005   5.0 0.005   1
   19    18    18    0.000000    129.937 +      0.018            S18               10.0 0.003 0.005   5.0 0.005  
   19    18     2  273.365501   1706.732       -0.417            PIN 46            10.0 0.003 0.005   5.0 0.005  23
    2    19    19    0.000000   1706.732 +      0.417            S19               10.0 0.003 0.005   5.0 0.005    
    2    19     1  270.192748                                    PIN 102           10.0 0.003                      
   11    10    10    0.000000    138.726 +     -4.803            S10               10.0 0.003 0.005   5.0 0.005  
   11    10    12  141.111000     47.778 *     -2.151            S12               10.0 0.003 0.005   5.0 0.005   1
   11    10    20  296.162248     21.678 *     -1.514            S20               10.0 0.003 0.005   5.0 0.005   1
End
; '*' = one-way distance/VC observations
; '+' = repeated reciprocal distance/VC obs (excluded in LS)

  • Where there is no distance or vertical component observed to a backsight and the value for the horizontal 'angle' is shown as '0.00000', lines such as

    2     1     1    0.000000                                    PIN 102           10.0 0.003

    may occur where the fields for distance or vertical component are empty - it is not a mistake but simply indicates no horizontal or vertical distance components were observed; the line may be deleted if the line following is an angle observation, but must be retained if it represents the backsight observation for a set of direction observations that follow (if in doubt, leave as-is)

    • A '*' following a distance value indicates that this is an unbalanced one-way distance observation to which curvature-refraction correction will be applied if required - DO NOT remove the '*'

    • A '+' following a distance value indicates that this is a duplicate distance/VC. The values may be necessary for the processing of a complete traverse sequence but will be omitted from a least-squares adjustment - DO NOT remove the '+'

    • A comment line may be inserted into the data at any position, or an existing data line may be commented-out (i.e., will be excluded from processing) by the insertion of ';' as the first character on the line. Any line marked in this way will be ignored during processing
 

                
<At>,<From>,<To>,<HAngle>,<HDist>,<Flag>,<HtDiff>,<Ht>,<Desc>,<Sdev>,<Cent>,<Const>,<PPM>,<Sdev>,<Bay>
9015,9014,9014,,215.091,*,-1.307,298.673,WM015,,,0.005,5,0.005,0
9015,9014,9016,174.4419,210.183,*,1.433,301.413,WM016,10,0.005,0.005,5,0.005,0
9016,9015,9017,185.1616,241.165,*,1.766,303.179,WM017,10,0.005,0.005,5,0.005,0
9017,9016,9018,174.192,200.212,*,1.442,304.621,WM018,10,0.005,0.005,5,0.005,0
9018,9017,9019,183.4747,217.436,*,2.156,306.777,WM019,10,0.005,0.005,5,0.005,0
9019,9018,9020,179.16,205.992,*,3.080,309.857,WM020,10,0.005,0.005,5,0.005,0
9020,9019,9021,182.0559,239.670,*,3.127,312.984,WM021,10,0.005,0.005,5,0.005,0
9021,9020,9022,175.3815,243.591,*,3.576,316.560,WM022,10,0.005,0.005,5,0.005,0



Observation types

The format of the Extract file permits numerous different types of observations to be defined; the point numbering convention largely determines the type of observation as follows ...

Point Number Field
Observation
Type 		Instrument
Station (At) 		Reference
Station (RO) 		Observed
Point (To)
Angle At RO To
Direction (b/s) At RO RO
Direction (f/s 1) At RO To
Direction (f/s 2) At RO To
Azimuth / bearing At 0, blank or At To
Distance / Ht Diff / Ht * At 0 or blank To
* A distance, height difference or height observation may be incorporated into any other observation type

When processing an Extract file (Process Extracted Observations option) Geoida will determine the observation type according to this convention and the values present.

For more details of the conventions by which Geoida determines the observation types and how the convention can be manipulated for further advantage, refer to Observation Conventions and Types for Traverse and Network.

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