Resection

This command allows you to calculate coordinates of an unknown instrument setup point given the angles and distances from up to 10 distinct reference points as stored in the active job and/or within a linked Control File. The routine follows Resection Sets, if enabled.

• Point ID: Indicate an existing point number that is to be used in the resection solution.

  Note: The point(s) can be established through the existing Point List or through a Map Screen pick.

• Desc, N, E, Z: Displays the Description, Northing, Easting and Elevation, respectively, of the specified point.
• Status: Describes the current instrument status.
• Horizontal: Displays the current Horizontal angle of the instrument.
• Zenith: Displays the current Vertical angle of the instrument.
• Inst Hgt: Specify the height of the instrument.
• Target Hgt: Specify the height of the target.
• Read: Initiates a measurement to the specified point. The angle right, zenith angle, and slope distance are recorded.
• Calculate: Once two or more resection points have been measured (three or more for Angle Only measurements), use the Calculate button to determine the current instrument location.

  Note: You can return to the resection routine to gather additional data and also choose the desired backsight point.

• Ignore Elev: When enabled, the elevation aspect of the resection will not be used and an elevation for the instrument location will not be calculated. When elevations are used, measurements will contribute to the calculation of the setup point elevation.
• Angle Only: This is useful when sighting radio towers and church steeples with known coordinates. Three or more points are necessary for an accurate calculation.

  Note: You do not need to change to reflectorless mode, since by definition no distance will be measured (i.e. you can stay in prism mode). If measurements are taken to steeples and radio towers and only horizontal position is known or the precise elevation point to sight is not known, then only the X,Y position of the occupied point will be determined accurately, and high Z RMS values will result.

• Turn to Pt: Directs the instrument to turn to the specified point based on the current resection information.

  Note: Be sure to set the correct target height for the additional resection points.

• Robotics: (Settings for conventional total stations) Use this button to configure aspects of the currently selected instrument.

  Note: The prism constant in the FS setting is what is used for all Resection measurements.

• Configure: Use this button to Configure settings related to the acceptable errors (useful for Least Squares Adjustments) and how measurements are taken.

During a Two-Point resection, the user will have the option to hold the first located point and the azimuth between the two located points by checking the Rotate Only checkbox. If the Rotate Only checkbox is unchecked, both located points will be held (normal resection).

Configure

The Configure option permits various error tolerances and the ability to control Standard Errors and methods for how measurements are taken.

• Distance Standard Errors:
  • Constant: Constant portion of the distance error. This value can be obtained from published EDM specifications, or from an EDM calibration.
  • PPM: Parts per million component of the distance error. This value can be obtained from published EDM specification, or from an EDM calibration.
• Angle Standard Errors:
  • Pointing: The horizontal angle pointing error is influenced by atmospheric conditions, optics, experience and care taken by the instrument operator.
  • Reading: Precision of horizontal angle measurements, obtained from theodolite specifications.
• Setup Standard Errors:
  • Resect Pt ID: The expected amount of error in setting the total station over the point.
  • Foresight Pt ID: This value is the expected amount of error in setting the target or prism over the point being measured.
• Backsight: Indicate how the backsight will be determined.
• Direct & Reverse: When enabled, instrument errors can be minimized via a turned set. This can also be toggled via Configure - Sets and its Resection toggle.

  Note: If you choose Direct & Reverse, then the reverse measurements count as part of the 20 allowable measurements, so the maximum number of reference points becomes 10.

• Split angle and dist: When enabled, measurements to a target point are split into an angular component and a distance component.

Calculate

If enough information is known to perform a resection, the results are displayed for review. The input data is displayed in a list structure, and you have the ability to turn certain measurements on/off and recalculate the solution, without the necessity of re-measurement. You can also edit point numbers, instrument and rod heights, and more here.

When satisfied with your edits and the solution, you can store the results of the resection.

Since there is redundant data, the final calculated coordinate differs slightly from the individual measurements. The command reports the calculated Northing, Easting, and Elevation coordinate, and the difference between the calculated coordinate and the individual solutions as residuals, which indicate the quality of the data. High residuals suggest a problem with the input data. If you select Orange Arrow, you are returned to the Read screen in case you want to collect more measurements.