Select a portion of the image to edit. Selecting a chain is the equivalent to marking elements in the GraphiCAD, Picture to Part, and Mill modules. Edit Chain enables you to edit only portions of the image. Edit Chain is activated by selecting this option from the command bar or clicking F8 shortcut key and clicking the desired chain, or by pressing Ctrl while clicking on the desired chain. The selected element appears with nodes (circles/rectangles marking the control points).

You can apply some actions on the selected element:

Draw freehand. This feature is useful for tracing a picture background manually. When you select Sketch, a dialog box with the Sketch options appears:

Figure 2.16. Sketch Dialogue

While sketching, you may switch back and forth between the Tangent and Corner options.

Press Esc to quit the sketching mode and return to the editing mode.

Erases portions of the drawing that are not required. Activate the feature Delete Chain from the Modify menu.

Upon selecting this option, the cursor will change to a delete cursor .

Delete part of the chain and break it. The chain will break only between two neighboring control points.

Activate the feature Break Chain from the Modify menu or by using the F7 keyboard shortcut. Position the cursor on the part to be deleted and click the left mouse button. This command is repetitive and is terminated by pressing Esc or making a new selection from the Modify menu. To select a new chain, simply press Ctrl while clicking with the mouse on a new chain.

Upon selecting this option, the cursor will change to a break cursor .

Enables you to change the nature of any geometry from one based on curves and/or polylines to one based on either curves or polylines.

Change Chain Type is activated by selecting this option from the Modify menu. This command is repetitive and is terminated by pressing Esc or by making a new selection from the Modify menu. To select a new chain, simply press Ctrl while clicking with the mouse on a new chain.

Upon selecting this option, the cursor will change to a change chain type cursor .

Figure 2.17. Change Chain Type Example

Filter unnecessary entities. Selecting this function will open the Filter Parameters dialog box. Enter the Minimal chain length for filtering. All chains of smaller length will be deleted.

Figure 2.18. Filter Short Chains Dialogue

Reduces the number of control points along all the curves in your job. This option is very useful when tracing a "noisy" image with groups of control points which do not contribute to the shape of the original image. You can reduce the number of control points that describe the image.

Figure 2.19. Global Reduce Points Dialogue

Enter the Tolerance value, which defines the approximation of the new curves regarding the original curves. Press OK to confirm or Cancel to abort this option. The new curves will have fewer points only if the tolerance is loose enough; this requires some "feel".

To change any arc on the selected geometry into a vertex of two line segments. With this function, you can change a figure with rounded corners into a figure with angular corners.

Figure 2.20. Force Corner Example

To apply this function, select the object. Choose Force Corner from the Modify menu. Place the cursor on the point that is to be the vertex and click with the mouse. Pressing F5 or pressing Force Corner on the toolbar can also activate Force Corner. To select a new chain, simply press Ctrl while clicking with the mouse on a new chain. Force Corner is repetitive and is terminated by pressing Esc.

Upon selecting this option, the cursor will change to a force corner cursor .

To change an angular corner into a rounded corner. The Force Tangent function is the inverse of the Force Corner function. Force Tangent is repetitive and is terminated by pressing Esc.

Figure 2.21. Force Tangent Example

To apply this function, select the object. Choose Force Tangent from the Modify menu. Point the cursor on the corner to be rounded and click on the mouse. Force Tangent may also be activated by pressing F6, or by selecting Force Tangent on the toolbar. To select a new chain, simply press Ctrl while clicking with the mouse on a new chain.

Upon selecting this option, the cursor will change to a force tangent cursor .

Filter a group of extraneous points along a desired polyline in order to achieve a straight line. The new line can then be edited like any line segment.

Figure 2.22. Line Filter Example

To use this function, select the object. Choose Line Filter from the Modify menu. Three points must be selected to apply the filter: the starting point, the direction point (a point between the starting point and the end point), and the end point. After the third point is selected, a single line segment appears. This line segment connects the starting point and the end point. To select a new chain, simply press Ctrl while clicking with the mouse on a new chain.

Filter a group of extraneous points along a desired arc in order to yield a clear arc. The Curve Filter function is analogous to the Line Filter function in its application, and the result is a single arc instead of a line segment. The resultant arc can be edited like any other arc.

Figure 2.23. Curve Filter Example

To use this function, select the object. Choose Curve Filter from the Modify menu. Three points must be selected to apply the filter: the starting point, the direction point (a point between the starting point and the end point), and the end point. After the third point is selected, a single curve appears. This curve connects the starting point and the end point. To select a new chain, simply press Ctrl while clicking with the mouse on a new chain.

Reduce the number of control points along a curve. This option is very useful when tracing a "noisy" image with groups of control points, which do not contribute to the shape of the original image.

Figure 2.24. Reduce Points Example

To use this function, select the object. Choose Reduce Points from the Modify menu. Three points must be selected to apply the filter: the starting point, the direction point (a point between the starting point and the end point), and the end point. After the third point is selected, the Tolerance dialog box appears:

Figure 2.25. Global Reduce Points Dialogue

Enter the Tolerance value, which defines the approximation of the new curve regarding the edited curve. Press OK to confirm or Cancel to abort this option. The section of chain that has been selected will be replaced with a new curve. The new curve will have fewer points only if the tolerance is loose enough; this requires some "feel". To select a new chain, press Ctrl while clicking with the mouse on a new chain.

Used on a raster image, before tracing it into a vector image. By adding graphical filters to the raster image you are able to trace the image with greater ease and precision.

Select Edit Picture from the Modify menu; the Raster Filters dialog box will open. You can now edit the picture using the graphical filter option and the scale variants.

Figure 2.26. Raster Filters Dialogue

To use this function, select the object. Choose Curve Filter from the Modify menu. Three points must be selected to apply the filter: the starting point, the direction point (a point between the starting point and the end point), and the end point. After the third point is selected, a single curve appears. This curve connects the starting point and the end point. To select a new chain, simply press Ctrl while clicking with the mouse on a new chain.