LEAST SQUARES ADJUSTMENT VERSION 8hturner/ce240/adj_8.pdf · In the MicroStation Manager dialog...

Adjustment Training Manual 2003

LEAST SQUARES ADJUSTMENT VERSION 8.0

LABORATORY MANUAL

INSTRUCTOR

DR. HOWARD TURNER P.L.S.

MAPPING SCIENCES CENTER OF EXCELLENCE COLLEGE OF ENGINEERING

CALIFORNIA STATE POLYTECHNIC UNIVERSITY, POMONA 3801 W. TEMPLE AVE.

POMONA CA 91768

Copyright Howard Turner 2003


Introduction No matter how careful a surveyor is, there are always errors in measurements. No matter what method of measurement is used, no two surveyors get the same measurements. Therefore,

No measurement is exact. ♦

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♦

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Every measurement contains errors. The true value of a measurement is never known. The exact error present is never known.

Using mathematics, these errors can be adjusted to minimize the inaccuracies. In some types of problems, the sum of several measurements must equal a known value; for example, the sum of the interior angles of a quadrilateral (a closed loop traverse) must equal 360 degrees. Therefore, the angles of the quadrilateral can be adjusted so that they add up to 360 degrees. You can also adjust horizontal or vertical distances. You can use the Adjustment commands at any time during a design session to display, review, and analyze survey data and adjust traverses, networks and side shots to minimize random errors. Before you can process survey data with the Adjustments commands, you need to set up files to hold the adjustments: these files are almost identical to the way alignments are set up. Basically, the software stores the information at two levels: adjustment project and adjustment set



Lab 1 - Getting Started In this lab you will: Review how to start the InRoads Survey program Review how to exit InRoads Survey Program and

MicroStation

1. Start Inroads Survey by choosing the item from the Start Menu with a left mouse click.

NOTE: MicroStation opens.

2. In the MicroStation Manager dialog box, change the working directory and select level_lab.dgn as the design file (Create level_lab.dgn if needed), and click OK.



The main Inroads Survey Menu opens inside MicroStation



Lab 2 Leveling

1. To create a level adjustment you must first create an adjustment project file by using notepad. Create the file containing the following data and save the file in your folder as level_test.txt.

begin points 1 1000 1000 281.13 /fixed 2 1000 2000 290.0 /free 3 2000 1000 310.0 /free 4 3000 1000 280.0 /free end points begin height_differences 2 1 11.973 4 2 10.940 4 1 22.932 2 3 21.040 4 3 31.891 1 3 8.983 end height_differences

2. . Select Adjustments>Set>Import from ASCII.



The Import Adjustment ASCII window opens

3. Select level_test.txt as the file name. Type level_test as the New Set Name and click Import. 4 Select Adjustments>Least Squares.



The Least Squares Adjustment form appears.

5. Set Apply Adjustments to: 1D, and press Adjust. The Review Least Squares Adjustments window appears.

6. Press Report.



The Least squares Adjustment Report form appears.

7. Press Save as. The Save As form appears. Save the file as level_test.rpt. Review the file by opening it in Notepad.



Lab 3 Traversing

1. To create a level adjustment you must first create an adjustment project file by using notepad. Create the file containing the following data and save the file in your folder as traverse_test.txt.

begin points D1 1975.328 8847.314 /fixed D2 2345.083 8901.159 /fixed D3 2529.454 9136.265 /fixed D4 2780.360 8911.363 /fixed D5 3003.060 8877.048 /fixed P11 2297.0 8672.00 /free P12 2526.0 8438.0 /free P13 2706.0 8442.0 /free P14 2889.0 8671.0 /free end points begin angles D2 D1 P11 290-04-41 D2 D3 P11 153-41-18 P11 D2 P12 123-39-21 P12 P11 P13 133-31-17 P13 P12 P14 129-39-32 P14 P13 D4 116-54-55 D4 P14 D3 156-19-53 D4 P14 D5 303-13-03 end angles begin horizontal_distances D2 P11 233.998 P11 P12 327.334 P12 P13 179.258 P13 P14 293.638 P14 D4 263.604 end horizontal_distances begin points 1 1000 1000 281.13 /fixed 2 1000 2000 290.0 /free 3 2000 1000 310.0 /free 4 3000 1000 280.0 /free end points begin height_differences 2 1 11.973 4 2 10.940 4 1 22.932 2 3 21.040



4 3 31.891 1 3 8.983 end height_differences

2. . Select Adjustments>Set>Import from ASCII.

The Import Adjustment ASCII window opens



3. Select traverse_test.txt as the file name. Type traverse_test as the New Set Name and click Import. 5 Select Adjustments>Least Squares.



The Least Squares Adjustment form appears.

5. Set Apply Adjustments to: 2D, and press Adjust. The Review Least Squares Adjustments window appears.

6. Press Report.



The Least squares Adjustment Report form appears.

7. Press Save as. The Save As form appears. Save the file as traverse_test.rpt. Review the file by opening it in Notepad.



APPENDIX I

GENERIC FILE SETUP begin points /free /fixed /side point data point data name x y z /free /fixed /side end points begin directions /sd= observation data observation data bundle_id at to val sd end directions begin azimuths /fixed /sd= observation data at to val sd observation data at to val /fixed sd end azimuths begin angles /sd= /ih= /fh= /bh= observation data observation data at from to val sd ih fh bh end angles begin vertical_angles /sd= ih= /fh= observation data observation data at to val sd ih fh end vertical_angles begin zenith_angles end zenith_angles




begin horizontal_distances /sd= /ppm observation data observation data at to val sd ppm ih fh bh end horizontal_distances begin slope_distances /sd= /ppm= /ih= /fh= /bh observation data observation data at to val sd ppm ih fh bh end slope_distances begin height_difference /sd= observation data observation data at to val sd in fh end height difference The following is a list of the qualifier abbreviations for the individual observation data entries: bundle_id name of direction set at instrument at, or occupied, point to foresight point from backsight point val measured value sd standard deviation (in seconds for angular observations and in feet or

meters for linear units) ppm parts per million del_x change in x-coordinate del_y change in y-coordinate del_z change in z-coordinate in instrument height fh foresight point target height bh /backsight point target height

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