Applet Components

• Instruction panel:

In this panel the applet gives information to the user regarding the execution of the algorithm and the status of the applet.

• Drawing Area:

This is the white canvas where the user enters the polygonal chain to be approximated by the iterative end-points fitting algorithm. The user enters the polygonal chain by clicking in this area. The user must double-click on the last point of the polygonal chain.

• Error Bar:

This is a scroll bar used to set the error tolerance required of the approximation. This error is measured in pixels.

• Distance Criterion:

This is a menu to select which criterion should be used by the algorithm to obtain the approximation.

• Procedure Buttons:

These are a set of buttons that allow the user to apply the algorithm.

Distance Criterion

This applet is equiped with two different distance criteria: Segment-Distance and Parallel-Strip. The difference between these distance criteria is described below:

• Segment-Distance
  This criterion specifies the distance as the minimum distance of a point P to all points X, such that X belongs the the segment being considered.

The selection of a point is illustrated in the figure below. The distance in consideration is drawn in magenta while the segment is drawn in green.



• Parallel-Strip
  This criterion specifies the distance as the minimun orthogonal distance from a point to the line containing the line-segment.

The selection of a point is llustrated in the figure below. The distance being considered is highlighted in magenta while the line containing the line-segment is highlighted in green.



Back to Applet Components

Procedure Buttons

• Clear All:

This button is used to clear the drawing area and restart the algorithm.

• Repeat Polychain:

This button is used to restart the algorithm using the polygonal chain previously specified.

• Show Approximation:

This button is used to execute the algorithm on the polygonal chain inserted by the user. The approximation is drawn in blue on the drawing area.

• Apply Step:

This button is used to execute only one step of the algorithm. The points being considered are painted in orange on the drawing area. The distance being considered is highlighted in magenta whereas the segment against which the distance is considered is drawn in green. The algorithm progressively builds the approximation highlighting the selected points in blue.

Back to Applet Components