Curving Line Features

The Curving pop-up menu, shown below, gives access to options that allow you to change the shape of the lines being drawn between feature points.  The shape of the line feature is governed by existence of curve comma codes on points.

Curve

• Segment will add the curve comma code to the points at either end of a line feature segment.  Please note that a single line feature segment cannot be curved unless at least one end has the curve tangent comma code.  Without tangents, it takes at least three points to describe a curve.
  
  
• Between will add the curve comma code to the points between two indicated points on a line feature.  As it is expected that curving will take place between the two points, the two indicated points will also have the curve comma code added.
  
  
• All will add the curve comma code to all the points of an indicated line feature.  As it does this, it will also remove any tangent or discontinuity comma codes from the points.

Before Curve Fitting	After Curve Between	Before Discontinuity	After Discontinuity

• Discontinuity will add the curve discontinuity comma code to an indicated point on a line feature.  A discontinuity is where two curves start at a common point but do not share a tangent through that point.

Tangent

• Point will add the curve tangent comma code to an indicated point on a line feature.  In the example shown below, the two most northerly points have been indicated.  This is one way in which you can create a single curved segment on a feature.  The other way is by having one point with a tangent comma code and the other with a curve or discontinuity.

After Tangent Point	Before Straight Point	After Straight Point

• Segment allows you to add a curve tangent comma code to the end points of a line feature segment.  This is often all that is necessary to simulate the curved parts of the pedestrian refuges found on urban roads.
  
  
• Between operates in the same way as the Curve Between option except that the indicated points will have tangent comma codes applied to them rather than the normal curve comma code.  The points in between the indicated points will have the curve comma code applied
  
  

Straight

• Point will remove all curve comma codes from an indicated point on a line feature.  This means that if either of the segments using the indicated point were curved, they would become straight.  In the example shown above, the curve was generated though the three north-westerly points.  Removing the curve comma code from the most westerly nullifies any effect of the other two points.

• Between will remove all curve comma codes from those points between two indicated points.  Any curve comma codes on the two indicate points will remain.
  
  
• All will remove all curve comma codes from the points of a line feature.

Arc Fit

• Between will cause the points on the string between those indicated to be moved as best as it can to a theoretical curve.  Note at least 3 points are needed to construct a curve.
  
  
• All will cause all the points on an indicated string to be moved as best as it can to a theoretical curve.  Note at least 3 points are needed to construct a curve.