COGO coordinate geometry

COORDINATE GEOMETRY

Traverse, Sideshot, Area, Brg-brg intersection, Brg-dist intersection, Dist-dist intersection, Inverse, Inverse Curve, Create Curve, Pt.On Curve, Offset Intersection

Angle and bearing/azimuth entry conventions
Throughout the program, angles, bearings, and azimuths are entered in the form of DDD.MMSS. If decimal portions of a second are used, simply continue the seconds entry. No extra decimal points are needed. For example, an entry of 45.23415 is 45 degrees 23 minutes and 41.5 seconds. If minutes and seconds are zero, only the degrees portion need be entered. If the degrees portion is zero, the minutes and seconds entry must be preceeded by a decimal.

Angle and bearing buttons are used to define the type of angle or bearing entered.

quadrant bearing: northeast – NE
southeast – SE
southwest – SW
northwest – NW
azimuth: north – NA  or south – SA (these buttons will only appear if you have selected NA or SA in Options)

angle: left – AL
right – AR
deflection: left – DL
right – DR

Reference Bearing
The bearing or azimuth between the current “from point” and the last “from point” is the reference bearing. To use, enter the desired angle in the bearing field and press “AL” (angle left) or “AR” (angle right) code button. The resulting bearing will be the reference bearing plus or minus the specified angle.

Bearing and distance recall
Instead of entering a bearing or distance, the bearing or distance between any two points may be recalled by entering the point numbers separated by a comma (“,”). Bearings may be modified by adding or subtracting an angle. Distances may be modified by dividing and by adding or subtracting (divide first.)

For example:
1,2 (recall the bearing or distance between points 1 and 2)
1,2+90 (add 90 to the bearing recalled from points 1 and 2.)
1,2/3+10 (divide the distance recalled from 1 to 2 by 3, then add 10.)

COGO entry fields
COGO coordinate geometry

From:
Enter the starting or occupied point #. If the point does not already have coordinates stored, the program will prompt for them. The program will display the coordinates and description. You only need to enter this field again when you want to move to a new starting point. The reference bearing will be undefined when you enter a new From point, and the area is zeroed.

To:
Enter the point number of the “to” point.

De:
Enter up to 20 alphanumeric characters to be used as a description for the point (optional).
-or- Tap within the edit box to modify the previous description.
-or- Use the up or down scroll arrows on the edit box, or the wheel on the side of the palm-size PC to scroll up or down the list of stored descriptions.

Bearing, Code, Distance:
These 3 fields will be described when used for the specific functions following.

COGO functions do not compute elevations, use the Collect functions for that.

TRAVERSE, SIDESHOT

This function computes a new point by traversing from the occupied (From:) point given a angle/bearing/azimuth and a distance.

Traverse

To:
Enter the new point number. This is where the computed point will be stored.

De:
Enter the description for the point (optional.)

Bearing:
Enter the angle from the reference bearing, or the bearing/azimuth, to the new point. If an angle is turned it will be turned from the reference bearing previously established into the currently occupied point.

Distance:
Enter the distance to the new point, and Press Traverse or Sideshot. The computed coordinates are displayed, and the program returns to the “To:” field.  For Traverse, the To: point becomes the occupied (From:) point and the bearing to the previous occupied point becomes the reference bearing. For a sideshot, the occupied (From:) point and reference bearing remain the same.

AREA

Press the Area button to display the area in square feet and acres (or square metres and hectares) of the figure which has just been enclosed by traversing or inversing (including curves and intersections). The area is then zeroed to begin computing another area. The area is also zeroed whenever you enter a new From: point, which signals you are not continuing around a closed area.

INTERSECTIONS

The fields for Intersections appear automatically if the button is selected, and either a distance or a bearing field is left blank. You simply enter the data you know, and leave the other fields blank, and the program knows which type of solution you want. This prompt will appear:

Intersect close pt:
Enter the point number of the intersection closing point. If you got into the Intersections function by accident, press X to return to the COGO entry screen.

Then, continue by entering a bearing or a distance, depending on the type of intersection desired. If there is no solution, the program displays ‘NO SOLUTION’, and returns to the “To:” field. Following are detailed instructions for each type of intersection available.

BEARING – BEARING INTERSECTION

This option computes an intersection point given a bearing from the occupied (From:) point and a bearing from a known (intersection closing) point.

BEARING - BEARING INTERSECTION

To:
Enter the intersection point number.

Bearing:
Enter the angle from the reference bearing, or the bearing/azimuth, to the intersection point.

Distance
No entry.

Press Traverse.

Intersect Close #
Enter the number of the intersection closing point.

Brg. from closing:
Enter the angle from the closing point, or the bearing/azimuth, to the intersection point.

The closing point becomes the occupied (From:) point and the bearing to the intersection point becomes the reference bearing. The closing point coordinates are displayed. The program then returns to the “To:” field.

BEARING – DISTANCE INTERSECTION

This program computes an intersection point given a bearing from the occupied (From:) point and a distance from a known (intersection closing) point.

BEARING - DISTANCE INTERSECTION

To:
Enter the intersection point number.

Bearing:
Enter the angle from the reference bearing, or the bearing/azimuth, to the intersection point.

Distance:
No entry.

Press Traverse.

Intersect Close #
Enter the intersection closing point number.

Brg. from closing:
No entry.

Dist. from closing:
Enter the distance from the intersection closing point to the intersection point.

For a Bearing-Distance intersection, there are two possible solutions. The program computes and displays the two possible distances from the currently occupied (From:) point to the intersection point. Press Short to choose the shortest distance solution or Long to choose the longest distance solution.

The closing point becomes the occupied (From:) point and the bearing to the intersection point becomes the reference bearing. The closing point coordinates are displayed. The program then returns to the “To:” field.

DISTANCE- DISTANCE INTERSECTION

This option computes an intersection point given a distance from the occupied (From:) point and a distance from a known (intersection closing) point.

DISTANCE- DISTANCE INTERSECTION

To:
Enter the intersection point number.

Bearing
No entry.

Distance
Enter the distance from the occupied (From:) point to the intersection point.

Press Traverse.

Intersect Close #
Enter the number of the intersection closing point.

Dist. from closing:
Enter the distance from the closing point to the intersection point. For a Distance-Distance intersection, there are two possible solutions. The program normally computes the clockwise solution. To choose the counter-clockwise solution, enter this second distance as a negative number.

The closing point becomes the occupied (From:) point and the bearing to the intersection point becomes the reference bearing. The closing point coordinates are displayed. The program then returns to the “To:” field.

INVERSE

This option computes the bearing and distance between the occupied (From:) point and a known point.

Inverse

To:
Enter the number of the known point, and press Inverse.

The known point becomes the occupied (From:) point and the bearing to the previously occupied point becomes the reference bearing. The bearing and distance to the known point is displayed and the known coordinates are displayed. The program then returns to the “To:” field.

INVERSE SIDESHOT

This option computes the bearing and distance between the occupied (From:) point and a known point as above, except it holds the From point constant.

CURVES functions

Inv.Curve
Computes and displays the curve data given the P.C., radius point, and P.T. of the curve.

Create
Creates the P.C., radius point, and P.T. of a curve from the P.I. of the curve, given the bearing into and out of the P.I., and either the radius, arc, chord or tangent.

P.O.C.
Creates a point on a curve (and the radius point, if unknown) from the P.C. of a curve. If the radius point exists, the program asks for the delta, arc, chord or tangent. If the radius point does not exist, the program asks for the bearing to the radius point, the delta, and either the radius, arc, chord or tangent.

NOTE: For all curve computations, clockwise curves are defined with a positive delta or radius, arc, chord or tangent distance and counter-clockwise curves are defined with a negative delta or radius, arc, chord or tangent distance.

INVERSE CURVE

This option computes curve data (delta angle, radius, arc, chord and tangent distance) given an occupied (From:) point (P.C.), a radius point, and a known point (P.T.).

Inverse curve

Radius point#
Enter the radius point number.

P.T. point#
Enter the point number of the P.T. of the curve. The program normally inverses the curve with a delta of less than 180º. To inverse a curve with a delta of greater than 180º, press the >180 button.

NOTE: If the distance from the P.C. to the radius point is not within.01 of the distance from the P.T. to the radius point, the program displays “RADII DO NOT MATCH”, and returns to the P.C. without inversing the curve.

The P.T. becomes the occupied (From:) point and the chord bearing becomes the reference bearing. The curve data and the P.T. coordinates are displayed. The program then returns to the “To:” field.

CREATE CURVE

The create curve option computes the P.C., radius point and P.T. of a curve given the P.I. (occupied (From:) point) and either the radius, arc, chord or tangent. Before coming into this function, you must establish the bearing into the curve by inversing or traversing into the P.I. of the curve.

Create curve

Radius point#
Enter the radius point number.

P.C. point#
Enter a point number for the P.C. of the curve.

P.T. point#
Enter a point number for the P.T. of the curve.

Brg from PI to PT
Enter the angle/bearing from the P.I. to the P.T. of the curve. If desired, you can enter the delta angle of the curve as an AR or AL to turn from the ref. bearing.

Enter curve data:
Enter the Radius, Arc, Chord, or Tangent distance for the curve, then press Radius, Arc, Chord, or Tangent.

Desired radius:
If a radius was not entered, the program displays the computed radius. To use this value, press OK, or enter a new radius.

The P.T. becomes the occupied (From:) point, and the bearing to the P.I. becomes the reference bearing. The curve data and the P.T. coordinates are displayed. The program then returns to the “To:” field.

POINT ON CURVE

This function creates a point on a curve from the P.C. (occupied (From:) point) of the curve with or without an existing radius point. If the radius point exists, you must supply a delta, arc, chord or tangent distance. If the radius point does not exist, you must supply a bearing to the radius point, the central angle (delta) of the curve and the radius, arc, chord or tangent distance.

Radius point#
Enter the radius point number.

* IF THE RADIUS POINT EXISTS *

Enter curve data:
Enter the Delta, Arc, Chord or Tangent distance for the curve, and press Delta, Arc, Chord, or Tangent.

P.O.C. point #
Enter a point number for the computed P.O.C.

The last P.O.C. established becomes the occupied (From:) point and the bearing tangent to the curve at the P.O.C. becomes the reference bearing. The program computes and displays the curve data.

* IF THE RADIUS POINT DOES NOT EXIST *

Brg to radius
Enter the bearing from the P.C. to the radius point. (In many cases, you could enter a 90 AR or AL to specify this bearing turned from the ref. bearing.)

Central angle
Enter the central angle (delta) of the curve. For counter-clockwise curves, enter a negative central angle.

Enter curve data:
Enter the Radius, Arc, Chord, or Tangent distance for the curve, then press Radius, Arc, Chord, or Tangent.

Desired radius:
If a radius was not entered, the program displays the computed radius. To use this value, press OK, or enter a new radius.

P.O.C. point #
Enter point number for P.O.C. The program computes and displays the curve data.

The P.O.C. established becomes the occupied (From:) point and the bearing tangent to the curve at the P.O.C. becomes the reference bearing. The P.O.C. coordinates are displayed.

OFFSET INTERSECTION

This option computes a point at the intersection of offsets from 2 lines.

OFFSET INTERSECTION

Center Point#:
Enter the center point number.

First Bearing (or pt,pt):
Enter the bearing of the first line.

First Offset:
Enter the offset distance from first line. (+ = right, – = left.)

Second Bearing (or pt,pt):
Enter the bearing of the second line.

Second Offset:
Enter the offset distance from second line.

Offset point#:
Enter the point number to store the computed offset point. The program then returns to the main menu.

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