## MAGNET Field: Optical offsets

This article explains the offset routines available for use in MAGNET Field when doing optical surveys.

# MAGNET Field: Optical offsets

## Horizontal angle offset

1. Point number
2. Code
3. Prism height
4. Distance measurement to center of object (i.e., tree, column, etc.). The angle between center of object, prism, and instrument equals 90°.
5. Horizontal angle to center of object

Note: Items 4 and 5 can be observed in any order. When viewing points, only the inaccessible point will be shown.

## Horizontal and vertical angles

1. Point
2. Code
3. Prism height
4. Measure the horizontal and vertical angles to the prism.
5. Measure the horizontal and vertical angles to the inaccessible point.

Note: Items 4 and 5 must be done in the order shown. When viewing points, only the inaccessible point will be shown.

## Distance offset

1. Point, Code, Prism height
2. Click this icon to measure to the prism.
1. Toward/Away toggle: This is the distance from the prism in line with the instrument to the unoccupied point. For instance, away 2.560 and toward -2.560 directions are the same.
2. Left/Right toggle: Distance left or right of the prism to the unoccupied point. Left/right is from the prism to the instrument when the box is checked.
3. Up/Down toggle: Distance up or down from the prism to the unoccupied point.

## Hidden point

1. Point, Code
2. Height of bottom of prism
3. Set the distance between the prisms and the tolerance.
4. Record observation to top prism.
5. Record observation to bottom prism.

Note: Only the coordinates of the hidden point will be displayed.

## Two lines intersection

Using the dialog box, you can determine the horizontal and vertical (3D) coordinates of an inaccessible point, as an intersection of two auxiliary lines. You create these lines (by two points) and perform distance and angle measurements of the line’s points.

1. Point, Code, Prism height
2. Press button and measure to first point on line 1.
3. Press button and measure to second point on line 1.
4. Press button and measure to first point on line 2.
5. Press button and measure to second point on line 2.

Note: Measurements can be taken in any order. Height of the inaccessible point is the mean of the heights of the two lines. Only coordinates of the inaccessible point will display.

## Line and corner

1. Point, Code, Prism height
2. First point on line (farthest from inaccessible point)
3. Second point on line (closer to inaccessible point)
4. Angle (H and V) measurement to inaccessible point

## Line and offset

The inaccessible point lies on a perpendicular to point 1 and point 2.

1. Input point number, Code, and Prism height.
2. Measure to point farthest from the inaccessible point.
3. Measure to point closest to the inaccessable point.

A dialog box will appear.

1. Offset Distance Forward or Backward along or projected from line point 1 to point 2, measured from point closest (point 2) to inaccessible point
2. Offset Distance Right or Left of line from point 1 to point 2
3. Vertical offset from point closest (point 2) to inaccessible point

## Plane and corner

Create 3D coordinates of the inaccessible point.

1. Point number, Code, and Prism height
2. Click and measure to first point on the plane.
3. Click and measure to second point on the plane.
4. Click and measure to third point on the plane.
5. Click and measure angles to the inaccessible point.

## Column offset

1. Enter Point number, Code, and Prism height.
2. Press and measure distance and horizontal angle to center of column. Prism is located in the middle of the column or tree.
3. Press and measure the angle to the left side of the column or tree.
4. Press and measure the angle to the right side of the column or tree.

## Vertical search

Measure the ground point.

1. Enter the Point number, Code, and Prism height. Then aim the instrument at the prism point and ground intersection.
2. Press, and the instrument will begin a vertical search for the prism. Then it will record the vertical angle and slope distance to the prism.

Note: In the points screen, the coordinates will have a V in the notes column.