Resection

2 POINT RESECTION
2 point resection

This function computes the coordinates and elevation of the instrument point given two known points and the horizontal angle, zenith angle and slope distance to each of the known points in clockwise order. This is also called Free Station. FieldWorks resection has a high accuracy without strength of triangle concerns. The program computes the instrument point as though you were occupying point 1, backsighting point 2, and traversing to the instrument point. Therefore, point 1 should be your more accurate point, and point 2 simply needs to be far enough away from point 1 to be a good backsight point from 1. Elevation is calculated using the measurement to the first point.
2 point resection screen

Pt 1:
Enter the first known point number.

Pt 2:
Enter the second known point number.

HI:
Enter the height of the instrument.

HT:
Enter the height of target.

HA: , ZA:, SD:
Enter the horizontal angle, zenith angle and slope distance to each of the two known points. To get this data from a total station, press the Measure function button in the upper left corner of the screen.

Once the shots to both points are measured, press the Store function button. The program will display a precision indication. The distance between the two known points is calculated from the measurements and this is compared to the known distance between the coordinates. The difference over the known distance is displayed as a precision ratio.

Save as point#:
Enter a point number to save the calculated point. The program then returns to the Main Menu.

3 POINT RESECTION
3 point resection

This function computes the coordinates of your instrument point given three known points and two measured angles between them. (note: A 2 point resection is usually easier and more accurate when using an electronic distance meter.) The three points must be entered so that they form a clockwise loop of 1,2,3, instrument point as shown:
3 point resection screen

Pt 1,2,3: Enter the 3 known point numbers.

HI:
Enter the height of the instrument.

HT:
Enter the height of target.

HA1, 2, 3: Zero the gun on the first point, then enter the horizontal angle to the 2nd and 3rd known points. To get this data from a total station, press the Measure function button in the upper left corner of the screen.

Once the angles to the second and third points are entered, press the Store function button.

Save as point#:
Enter a point number to save the calculated point. The program returns to the main menu.

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