Generating a Surface

For many purposes, you will want to create a surface which is defined by several individual, intersecting objects. If such a generated surface is required for a command's execution, it can be defined as follows:

The objects whose outlines are to be included in the new surface are chosen. Click on objects to choose them.

If you need to temporarily close gaps or add outline elements for executing this command, please use the Dynamic Snapping Guide to add lines or curves before finishing object selection.

After choosing the objects, several reference points can be entered, one after another. These points can be entered using the mouse, by clicking anywhere in the drawing.

Use the buttons in the Parameter Window to select for each individual reference point which types of outlines shall be recognized:

The position of the reference points determines where and how the surface should be generated. Each reference point should be close to one of the outline elements to be incorporated in the surface. It shows with which element the search for a closed outline should begin. Through its position relative to this element, it also determines whether the "largest possible" or "smallest possible" surface should be worked out (see graphic).

The effect of the reference point can be explained (simply) as follows: Imagine emptying a can of paint at the reference point. The paint spreads out in all directions until it reaches an object.

The result is one area which is covered in paint, and one area which is not. The boundary between these two areas is the outline of the newly-generated surface.

As you enter the reference points, a preview is visible showing which outline would be created from the current position.

If multiple reference points are entered, one outline will be calculated for each of those reference points according to the method described above. The resulting outlines will then be combined to one surface. This way it's easy to generate complex surface (see graphic).

Reference point input can be cancelled or finished at any time using the Workflow Manager. Click the right mouse button to display the Workflow Manager and choose either the Cancel Command or Finish Command command.

If an error message appears, please check first if the chosen objects together really form a close surface, i.e. they all touch and/or overlap each other. To do so, it may be necessary to zoom in deeply. Only if the chosen objects seem to be sufficient and correct, and the surface should thus be possible to generate, try increasing the tolerance by a small step. Don't forget to reset the tolerance to its previous value once you're finished!

In the command's parameters, you can choose whether the result shall be automatically simplified, and set the corresponding tolerances (see "Simplify Curve / Surface" dialog).

As the result is a surface, only its possible elements (lines, circle arcs and Bézier curves) can be used when calculating the result. Many object types (above all, ellipses and ellipse parts) must therefore be converted to polylines first, which inevitably causes loss of quality. The precision of the conversion can be specified using the command Drawing Settings > Precision in the entry "Transform".

The selected objects, on the basis of which the surface is generated are neither deleted nor altered. If they are to be deleted, the easiest way is to use the command Delete Objects or press the DELETE key. The required selection can easily be made by pressing the F11 Key. This deletes exactly the objects used to generate the surface.