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Construction Point Selection Method v8i


Primarily during design work, it is necessary to specify points that are neither existing points nor known coordinates.  These points often require a geometric construction prior to deriving usable coordinates.  MX's Construction point selection method allows COGO like point construction.

Simple point constructions will only require a Single Element to derive point coordinates.  For all other point constructions, an Intersection of Elements is required.

Point or element constructions are displayed in purple as temporary graphics on the MX Display.  These graphics are removed when the Constructed Coordinates are accepted.

Obtaining a Construction Point Selection
Place the cursor in any Point Control box.  Right click to summons a pop-up menu containing all the available point selection methods for that operation.  Select the Construction point selection method.

         Point Construction Single Element panel

The Point Construction: 1st Construct panel for a Single Element construction is displayed.


Single Element Point Construction

The button icons representing the Element Types show the element to be constructed.  The points, lines, and circles that appear in Gray represent the required data.  The point that appears in Red represents the constructed point.

There are seven Element Types available with the Single Element point construction.

  1. Circle: 3 Points  Define a circle with 3 Points.  The center of this circle is returned as the Constructed Coordinates.
  2. Circle: 2 Points and Radius  Define a circle with 2 Points, a Radius, and a projection.  The projection is required to indicate which side of the 2 Points the center should be.  The center of this circle is returned as the Constructed Coordinates.
  3. Circle: 2 Tangents and Radius  Define a circle with 2 Tangents, a Radius, and a projection.  The projection is required to indicate which sides of the 2 Tangents the center should be.  The center of this circle is returned as the Constructed Coordinates.
  4. Line: Divide a Line  Define a line segment with 2 Points.  The line segment is divided by a Ratio value.  This point of division is returned as the Constructed Coordinates.
  5. Line: Point, Bearing and Distance  Define a line using a Point and Bearing.  The coordinates of a point at a Distance from the first point is returned as the Constructed Coordinates.
  6. Line: Angle and Distance  Define a line segment with 2 Points.  The coordinates of a point at an Angle and Distance from the first point is returned as the Constructed Coordinates.
  7. Line: Distance and Offset  Define a line segment with 2 Points.  The coordinate of a point at a Distance from the first point and an Offset from the line segment is returned as the Constructed Coordinates.

Intersection of Elements Point Construction

Point Construction Intersection of Elements panel

The Intersection of Elements is more involved than the Single Element construction.  It requires 2 single element constructions and possibly a decision as to which intersection is preferred.  The Title Bar for Point Constructions indicates whether the first or second element is under construction.

There are 10 Element Types available for intersecting.

  1. Circle: Center and Radius
  2. Circle: Center and Point
  3. Circle: 3 Points
  4. 2 Points and Radius
  5. 2 Points on Diameter
  6. 2 Tangents and Radius
  7. Line: 2 Points, Offset and Angle
  8. Line: Point and Bearing
  9. Line: Divide a Line

The button icons representing the Element Types show the element to be constructed.  The points and lines that appear in Gray represent the required data.  The lines and circles that appears in Red represents the element being constructed.

If more than one intersection exists, then the Next Intersection button becomes active.  It allows one to toggle between the geometric possibilities.   As long as one element is a circle, then there will be 2 intersections.  Use the MX Display to verify the desired choice.

Construction Sequence

  1. Select the Intersection of Elements Point Location Method.  The Title Bar should read Point Construction: 1st Construct.
  2. Select from one of the Element Types for the first element.
  3. Supply the required data for the selected Element Type.  Temporary graphics begin to appear as data is supplied.
  4. Click Accept to return to the Point Construction panel.  The Title Bar should now read Point Construction: 2nd Construct.
  5. Select from one of the Element Types for the second element.
  6. Supply the required data for the selected Element Type.  Temporary graphics continue to appear as data is supplied.
  7. If more than one intersection exists, use the Next Intersection button to toggle between the geometric possibilities.  Use the MX Display to verify the desired choice.
  8. Select Accept to return the Constructed Coordinates.  The temporary graphics are removed from the MX Display.




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