Draw and adjust polygon

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Purpose:

To dynamically draw a polygon specifying distance and bearing, azimuth, XY coordinates or angle with previous course.

You can import XY coordinate information from an existing text file or import information selecting an existing polyline in the drawing.

The polygon error of closure can be adjusted using the Compass or Transit Rule or by the Crandall Method and an Excel compatible Traverse Adjustment Report can be generated. Point numbers are automatically annotated.

This tool is useful if you need to reconstruct a polygon from legal documentation or from traverse surveying information.

Fig. 1: Main window

1. Toolbar buttons:

	Open course file. Open a CADSiteTools polygon file (*.cstp)
	Import XY text file. Draw a polygon importing reading a text file containing coordinate data per line (see fig. 2).
	Save course file. Save polygon information to file.
	Add linear course. Add a line segment indicating bearing or azimuth-distance, angle with previous course or XY coordinates.(see fig. 3)
	Add arc. Add an arc segment indicating bearing-distance or azimuth-distance, angle with previous course or XY coordinates. Arc can be created specifying chord or radius length and central angle (delta) or arc length.(see fig. 4)
	Add XY coordinate. Add a linear course specifying XY coordinates. Coordinate values can be typed or selected from screen.(see fig. 5)
	Edit current selected course. Change bearing or azimuth, distance, angle or coordinates from current selected course. If an arc course is selected radius, arc and chord length or central angle (delta) can also be updated.
	Delete current selected course. Current selected course data will be deleted and data from the following courses will be updated.
	Import polyline. Read course data selecting an existing polyline.
	Draw polygon. Create a polyline entity in AutoCAD from defined course data, optionally applying linear and angular error adjusting methods. A traverse adjustment Excel compatible report can be created. Point numbers can be annotated and arc adjustment options specified.

2. Point number and description. A number or string must be entered to identify the current course endpoint. Point description is optional.

3. Polygon description. Used to identify the polygon (optional)

4. Polygon Preview Window. Polygon drawing is updated every time a course is added, edited or deleted or a new polygon course file is opened. Current selected course is shown in green color. The view can be enlarged, reduced, moved or restored to its original extents selecting the view buttons at the left of the preview window.

5. Course Data Window. Formatted information from each course is displayed in each row. Hovering the mouse pointer over the current selected row will display additional information. Data will be formatted according to course type (line, arc or XY coordinate). After a row selection is changed the image in the Polygon Preview Window will be updated, showing the corresponding point number and description and the selected course in green color in the Polygon Preview Window.

Import XY Text File

Fig. 2: Import XY text file window

1. File format. The selected coordinate format must correspond with the data format in the text file. e.g.: if the text file contains number of point, coordinate X and Y per line, then the file format selected in the list must be nXY.

2. Value separators. If the data in the text file is separated with characters other than blank spaces, each separator must be typed in the box and the 'Add' button must be pressed to add it to the list. e.g, if data in the text file is separated by commas, the comma character must be added to the list.

3. Skip first line from file. If the first line of the text file is a header, this option must be selected to ignore it and process the following line.

Add Line Course

Fig.3: Add line course

1. Bearing/Azimuth angle: If the bearing format option is selected the North (N), South(S), East (E) and West (W) directions can be selected. Bearing degree values must be entered between 0 an 90 degrees and azimuth degree values between 0 and 360, minutes and second between 0 a 60.

2. Angle selection button. Press this button to get an angle value between two selected points.

3. Distance. This value can be typed or selected specifying two points in the drawing.

4. Distance selector button. Press this button to get the distance between two selected points.

5. Specify angle with previous course. Press this button to set right/left or deflection angle relative to previous course. Bearing or azimuth angle will be calculated automatically.

6. Specify point coordinates. A dialog box will be displayed to type the X Y coordinates or select a point in the drawing.

· Tip: Pressing ENTER after typing the degree value will get you to the next box where you can type the minutes value. Likewise, after typing the minutes value pressing ENTER will get you to the next box where you can type the seconds value.

· Tip: If you type a degree value with decimal places and press ENTER the minutes and seconds box will be filled automatically. e.g., typing the degree value of 25.1475 and pressing ENTER will automatically place the value of 25 in the degrees box, 8 in the minutes box and 51.00 in the seconds box (25.1475 decimal degrees is equivalent to 25° 8' 51.00").

· Tip: Pressing enter after typing the distance value will automatically add the line course and the Polygon Preview Window will be updated. The degrees box will be automatically selected ready to enter data for the next course.

Add Arc Course

Fig. 4: Add arc

2. Angle selection button. Press this button to get an angle value between two selected points.

3. Chord or radius length. This value can be typed or selected specifying two points in the drawing.

4. Distance selector button. Press this button to get the distance between two selected points.

5. Specify angle with previous course. Press this button to set right/left or deflection angle relative to previous course. Bearing or azimuth angle will be calculated automatically.

6. Specify point coordinates. A dialog box will be displayed to type the X Y coordinates or select a point in the drawing.

7. Angle reference. Chord: bearing or azimuth angle value can be referenced to the arc chord or to the radius from the start point to the center of the arc.

8. Arc data: Arc can be constructed specifying radius, arc length or central angle (delta). If the 'Tangent to previous course' option is selected the chord bearing will be calculated so the arc maintains tangency with the previous course. If the 'Tangent to previous and next course' option is selected the radius, arc length and central angle (delta) will be calculated so the arc maintains tangency to the previous and next course.

9. Curve bows to: Select if curve bends to the right or left.

· Tip: Pressing ENTER after typing the degree value will get you to the next box where you can type the minutes value. Likewise, typing the minutes value and pressing ENTER will get you to the next box where you can type the seconds value.

Fig. 5: Point coordinates

1. X coordinate box: Pressing ENTER will set the value and the Y numeric box will be automatically selected.

2. Y coordinate box: Pressing ENTER will automatically add the point and the Polygon Preview Window will be automatically selected. The X coordinate box will be selected ready to enter the XY coordinates for the next course.

3. Point selector button. Press this button to select a point in drawing.

Draw Polygon

Fig. 6: Traverse error adjustment.

1. Linear error of closure adjustment method. If the last point is not equal to the polygon's point of beginning (POB) the error can be distributed modifying the vertices coordinates. This adjustment can be made using the following methods:

Compass rule. Also known as Bowditch method. The distribution of the linear error of closure will be proportional to each segment length relative to the polygon length.

Transit rule. The distribution of the linear error of closure will be proportional to each segment departure(X projection) and latitude (Y projection) relative to the total sum of departures and latitudes.

Crandall method. A formula developed by Charles L. Crandall will be used for the distribution of the linear error of closure. This formula is based on least squares adjustment assuming equal weights for each measured distance.

Move last point to P.O.B. : Last point will be moved to the point of beginning (POB), all other vertices will be left undisturbed.

None: No linear error adjustment will be applied.

2. Angular error adjustment. The angular error is the difference between a measured angular value and a calculated angular value. The total angular error will be divided by the number of the polygon sides and added to each measured angular value. The angular error adjustment will be applied before the linear error adjustment.

This error can be calculated using the following methods:

By interior angles sum check: The measured angular sum will be obtained adding the measured interior angle values. The calculated interior angle total sum will be obtained using the formula (n - 2)*180 , where n is the polygon total number of sides.

By measured azimuth reference. Calculated azimuth of last course will be obtained taking as reference the azimuth of the first course and the traverse deflection angles. The measured azimuth angle of the last course must be entered typing the degrees, minutes and seconds values in the corresponding numeric boxes.

None. No angular error adjustment will be applied.

3. Create traverse adjustment report. Check to create a traverse adjustment Excel compatible report. After the polygon is drawn the report will be shown in the Report Viewer containing all the calculations made to compensate linear and angular errors, and the final adjusted coordinates and angles.

Fig. 7: Polygon annotations

1. Annotate point number. Check to label each polygon vertex when finished. The point numbers annotated will be the ones defined for each polygon course.

2. Text settings: Select layer, color style and font for the point number text annotation. Text size can be typed or selected in drawing pressing the distance selector button. Text size can be in drawing units or plotting units according to the defined paper space layout scale.

Fig. 8: Arc adjustment.

Set Course Angle

After applying the linear and angular error adjustments the polygon vertices coordinates will be modified. The starting and ending points of arc segments will no longer coincide, and the arcs must be adjusted. This adjustment can be made selecting the following options:

1. Maintain radius: The radius and degree of curvature of the original arc will be maintained. Central angle (delta) and arc length will be adjusted.

2. Maintain central angle (delta): The subtended angle of the original arc will be maintained. Radius and arc length will be adjusted.

3. Maintain arc length: The arch length of the original arc will be maintained. Radius will be adjusted.

4. Maintain tangent: The distance between the point of intersection (PI) of the arc tangents and the arc start point and endpoint of the original arc will be maintained. Radius and central angle (delta) will be adjusted.

5. Maintain middle ordinate: The distance form the middle of the chord and the middle of the original arc will be maintained. Radius and central angle (delta) will be adjusted.

Fig. 9: Set course angle

The course angle can be defined also specifying the angle or deflection with previous course. These angles are measured as follows:

1. Right angle. Measured from station point A to previous course backsight point, turning right to foresight point B.

2. Left angle. Measured from station point A to previous course backsight point, turning left to foresight point B.

3. Right deflection angle: The angle measured from station point A to a point in the direction of the prolongation of the previous course angle turning right to foresight point B .

4. Left deflection angle: The angle measured from station point A to a point in the direction of the prolongation of the previous course angle turning left to foresight point B.

5. Angle value numeric boxes: Right or left angle values must be entered between 0 an less than 360 degrees. Deflection angle values between 0 and less than 180 and minutes and seconds values between 0 and less than 60. Pressing ENTER when the seconds numeric box is active is equivalent to press the OK button.

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