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.

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.

**Circle: 3 Points**Define a circle with 3*Points*. The center of this circle is returned as the*Constructed Coordinates*.**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*.**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*.**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*.**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*.**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*.**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

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.

- Circle: Center and Radius
- Circle: Center and Point
- Circle: 3 Points
- 2 Points and Radius
- 2 Points on Diameter
- 2 Tangents and Radius
- Line: 2 Points, Offset and Angle
- Line: Point and Bearing
- 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**

- Select the
*Intersection of Elements Point Location Method*. The*Title Bar*should read**Point Construction: 1st Construct**. - Select from one of the
*Element Types*for the first element. - Supply the required data for the selected
*Element Type*. Temporary graphics begin to appear as data is supplied. - Click
*Accept*to return to the*Point Construction*panel. The*Title Bar*should now read**Point Construction: 2nd Construct**. - Select from one of the
*Element Types*for the second element. - Supply the required data for the selected
*Element Type*. Temporary graphics continue to appear as data is supplied. - 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. - Select
*Accept*to return the*Constructed Coordinates*. The temporary graphics are removed from the MX*Display*.