Intersects

This feature allows you to calculate intersections based on one of the following methods:

Bearing-bearing
The bearing-bearing intersect is calculated based on a line passing through a point on a given bearing intersecting another line passing through a second point on another specified bearing.

Bearing-distance
This is based on a line passing through a point at a given bearing intersecting a circle at a given distance (radius) from a second point.  This intersection by result in 2 points of intersection.

Distance-distance
This is based on intersecting a circle at a given distance (radius) from a point with another circle at another given distance (radius) from a second point.  This may also result in 2 points of intersection.

Perpendicular
This is based on calculating the perpendicular distance from a given point to a line that passes through another point at a specified bearing.

Tangent
This is based on calculating the tangent points of a line drawn from a given point to a circle having a specified radius and radius point.

Command line input
After selecting the Intersects option on the CGCogo pull down menu and the Use Intersects Dialog menu item is not checked you will see the following prompt.

Intersection method: Brng-Brng/Brng-Dist/Dist-Dist/Perp/Tangent or offsets-on
    [BB/BD/DD/Perp/Tangent/turn-Offsets-on]:

Bearing–Bearing Intersections:
Type “bb”, then press <Enter>
At the Enter first Point: prompt type in or pick the point using the mouse
As an illustration, using the example shown in the figure: type or pick point 2203.
At the Enter first bearing:  prompt there are 3 options available:
Type the bearing directly using the special C&G notation qddmmss (quadrant, degrees, minutes and econds)
105.2316 (N 05° 23’ 16”E)


Enter the two known C&G points that define the bearing either by typing the two points in with a dash between them or picking the two points one at a time using the mouse.
Or select a C&G line.  When you select a line the bearing is computed by inversing between the two points that created the line.  The bearing quadrant is based on traversing from the end point of the line farthest from the location where the line was picked to the end point of the line nearest to the point picked.

Enter second point: for the example type or pick point 2204
Enter second bearing: use any of the methods outlined for entering first bearing.
The intersection will then be calculated, the intersection point saved to the coordinate file and the results displayed at the command line.

When saving the intersection point, depending on your settings on the Global Settings tab of the C&G Options dialog, you may be asked to either enter or change the point ID, elevation, point code and description.

At each of the STORING POINT prompts there is an option to change settings [Settings].  Pressing S will bring up the Global Options tab of the C&G Options dialog box, allowing you to change settings prior to saving the point. (see the CGTools Chapter for a description of the CGOptions dialog box)

Bearing-Distance Intersection
Type bd to calculate the intersection of a circle with a line. Generally, the data is entered in the same fashion as for a bearing-bearing intersection.
Once the data is entered  each of the two solutions will be displayed one at a time.
You will be asked if the solution shown is the correct solution.  

Is this the correct solution [Yes/No/ESC]:

If the solution is the correct one press Y for <Yes>.  If it is not the correct solution press N for <No> and the second solution will be displayed.  If neither solution is correct press <Esc> to cancel and return to the previous prompt.

Distance-Distance Intersection
Type dd to calculate the intersection of two circles: with the distances being the radii of the circles
You will be prompted to enter the first radius point and distance (radius)
You will then be asked to enter the second radius point and distance (radius)
As with the bearing-distance intersection,  the two possible solutions will be displayed and you will be asked to choose the correct one (see dialog below).

If you click the No button the other possible solution will be displayed.  If you click the Yes button the intersection point will be stored.  If you click Cancel the point will not be stored.

The routine will continue with additional DD Intersections prompts until you escape [ESC] the routine.
The process will be repeated until the user presses <Esc> twice to end the command.

Perpendicular Intersection
Press P and <Enter> to calculate the point where the perpendicular constructed from a given point to a line intersects the line.
At the Enter first Point <>: prompt, type or pick a point on the line (in the example illustrated in the figure, type or pick point 2514)
At the Enter bearing: <>: prompt, type the bearing of the line or type or pick the two points defining the bearing (in the example, 2514-2513)
You will then be asked if you want to
Store Perp. Int. Pt. (Yes/No):
Choose whether to store the calculated point or simply view the data (you may not want to save the resulting intersection point).
Enter second point <>: Type the point ID, or use the mouse to pick the point from which the perpendicular to line is to be constructed (in the example, 2488).  
The STORE POINT prompt will indicate the point being stored (in the example it will be 2489). Press <ESC> to cancel point storage.
To exit the Instrsects feature, the user must press <Esc> twice or the routine will repeat.

Tangent Intersection

Type T and <Enter> to calculate the points at which a line from a given point becomes tangent to a circle. You must choose a radius point for the circle, the radius of the circle, and the external point from which the tangent will start.
At the Enter radius point for circle: prompt, type or pick the center or radius point of the circle (in the example, 2490)
At the Enter radius of circle: prompt, type the radius or type or pick two points that define the radius distance (in this example, 2490-2492, or 69.92’ )
At the Second point: prompt, type or pick the point through which the tangent lines must pass (in the example, 2491)
As in some of the other intersection types, you must select the desired solution from the two possible solutions using the dialog shown for the distance-distance intersect..  If you click the Yes button, he intersection point will then be saved to the coordinate file and the results displayed at the command line.
To end the command, press <Esc> twice or the routine will repeat

Turn-Offsets-on:


Type O and <Enter> to turn the use of offsets on or off .
An example of an offset intersection would be the easement lines for a sewer line.  This routine can calculate the offset intersection say for a 7.5’ left offset and a 10’ right offset, as shown.
For example:
Enter first offset distance <>: -7.50

Enter Second offset distance <-7.50>: 10.00
The offset distances are positive if right of the line, as seen looking down the line in the direction of the defined bearing, negative if left of the line.

Intersects dialog
If the Use Intersects Dialog menu item is checked you will see the following dialog:

To use the Intersects dialog just set the Intersect Type drop down list to specify the type of intersect you wish to do.  Next click on the item you wish to specify.  You may type in the information or you can move the cursor over the drawing area and you will be prompted for the information required for the edit box you were last in.  To enter the next item, click on that edit box and type the information or, as before, move the cursor over the drawing and you will be prompted for the necessary information for the last edit box you were in.  Continue to do this until all information has been entered then click the Compute button to compute the intersection.  The results will be printed on the CAD command line and to the print file.  If the Store Intersect Point check box is checked the intersection point will be stored in the coordinate file.  You may specify offsets by checking the Specify Offsets checkbox and entering or picking the offset distance(s). Click the Reset button to remove all entered data from the dialog.

You may perform any other commands while the Intersects dialog is displayed - the data entered in the dialog will remain for use at any time.

Prompts

Not using Intersects Dialog:
Intersection method: Brng-Brng/Brng-Dist/Dist-Dist/Perp/Tangent or offsets-on
    [BB/BD/DD/Perp/Tangent/turn-Offsets-on]: Type the 1 or 2 capitalized letters to specify the type of intersect to calculate or to turn offsets on.
point prompts
Enter point: Type a point ID or pick a point symbol on the screen.
Enter first point: Type a point ID or pick a point symbol on the screen.
Enter second point: Type a point ID or pick a point symbol on the screen.
Enter radius point for circle: Type a point ID or pick a point symbol on the screen.
Enter point on tangent line: Type a point ID or pick a point symbol on the screen.
bearing prompts:
Enter bearing <100.0000>: Type or pick the bearing.
Enter first bearing <100.0000>: Type or pick the bearing.
Enter second bearing <100.0000>: Type or pick the bearing.
distance prompts:
Enter distance <0.000000>: Type or pick the distance.
Enter 1st distance <0.000000>: Type or pick the distance.
Enter radius of circle <0.000000>: Type or pick the distance.
perpendicular intersect prompt:
Store perpendicular intersect point [Yes/No] <N>: Type "Y" or "N" and Enter.
Stopping to allow viewing of intersect point (red X) <Enter to continue> This prompt is displayed if you answered "N" to the previous prompt.  Just press Enter to continue.
Intersects dialog: Type or pick the data into the appropriate edit boxes then click the Compute button to view the results and save the intersection point to the coordinate file.

Pulldown Menu Location: CG-Survey > Cogo
Keyboard Command: cg_intersects
Prerequiste:  coordinate file