LEAST SQUARES ADJUSTMENT VERSION 8.0

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1 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 Page 1

2 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. 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 Page 2

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

3 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. Page 3

4 The main Inroads Survey Menu opens inside MicroStation Page 4

5 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 /fixed /free /free /free end points begin height_differences end height_differences 2.. Select Adjustments>Set>Import from ASCII. Page 5

6 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. Page 6

7 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. Page 7

8 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. Page 8

9 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 D /fixed D /fixed D /fixed D /fixed D /fixed P /free P /free P /free P /free end points begin angles D2 D1 P D2 D3 P P11 D2 P P12 P11 P P13 P12 P P14 P13 D D4 P14 D D4 P14 D end angles begin horizontal_distances D2 P P11 P P12 P P13 P P14 D end horizontal_distances begin points /fixed /free /free /free end points begin height_differences Page 9

4 3 31.891 1 3 8.983 end height_differences 2.

10 end height_differences 2.. Select Adjustments>Set>Import from ASCII. The Import Adjustment ASCII window opens Page 10

11 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. Page 11

12 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. Page 12

13 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. Page 13

14 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= end directions bundle_id at to val sd begin azimuths /fixed /sd= end azimuths at to val sd at to val /fixed sd begin angles /sd= /ih= /fh= /bh= at from to val sd ih fh bh end angles begin vertical_angles /sd= ih= /fh= end vertical_angles at to val sd ih fh begin zenith_angles end zenith_angles Page 14

15 begin horizontal_distances /sd= /ppm end horizontal_distances at to val sd ppm ih fh bh begin slope_distances /sd= /ppm= /ih= /fh= /bh end slope_distances begin height_difference /sd= end height difference at to val sd ppm ih fh bh at to val sd in fh The following is a list of the qualifier abbreviations for the individual entries: bundle_id at to from val sd ppm del_x del_y del_z in fh bh name of direction set instrument at, or occupied, point foresight point backsight point measured value standard deviation (in seconds for angular observations and in feet or meters for linear units) parts per million change in x-coordinate change in y-coordinate change in z-coordinate instrument height foresight point target height /backsight point target height Page 15

12D LEAST SQUARES NETWORK ADJUSTMENT FROM LEICA 1200

12D LEAST SQUARES NETWORK ADJUSTMENT FROM LEICA 1200 READINGS The following steps show the conversion of a Leica 1200 DBX file to a horizontal and level network adjustment file and the subsequent adjustments