Concatenating Surfaces

This task explains how to concatenate a two-cell mono-domain FreeStyle surface or two separate contiguous surfaces into a mono-cell surface.
The resulting surface is a curvature continuous surface (C2).
Open the Concatenate2.CATPart document.
This document contains a set of connex surfaces.

  1. Click the Concatenate icon .
    The Concatenate dialog box is displayed.

  2. Set the tolerance value.
 

This value defines the maximum parametric deviation allowed between the selected elements and the resulting curve when concatenating. 

The Maximum deviation value displayed in the dialog box (see step 5) is computed as the standard distance analysis and therefore is not necessarily the minimum tolerance value to be set in order to concatenate the curves.

  1. Select the surfaces you wish to concatenate and click Apply.
 

A single surface is previewed, with its segment limits in both U and V, provided the tolerance is compatible. If not, a message is issued prompting you to increase the tolerance value. 

The minimum tolerance value necessary to obtain a result displays as well.

  1. Change the tolerance value so that it is compatible to create a single surface.

  2. Click More>> in the dialog box.
 

  1. Check the Information option.
    The corresponding information is displayed on the resulting surface, that is:

  • Nu/Nv: number of control points in U and V

  • o: the curve order

  • s: the number of segments in the curve

  • the maximum deviation
 

In case you did not check the Information button, the maximum deviation is also displayed in the dialog box.

  1. Check the Auto Update Tolerance button to automatically update the tolerance value in case the value you set is too low.
    A minimum result to enable the concatenation is displayed and the concatenation is performed.

No message is issued prompting you to increase the tolerance value as the minimum value is set automatically.

  1. Click OK in the Concatenate dialog box.
    A surface is created, the result of the concatenation of the initially selected elements  (we changed its color to blue for easier identification). This surface is C2 continuous.

  • Only two cells, whether in the same element (join for example) or in separate elements (two different cells) can be concatenated at a time. To concatenate more, you need to concatenate the first two cells, then the resulting concatenated surface with another cell, and so forth.

  • If the selected surfaces are not connex (if there is an important gap between the two surfaces) the Apply button is grayed, and you cannot create the concatenated surface.
  • If the selected elements present a curvature discontinuity you will need to increase the tolerance value accordingly.
    In this case too, the maximum deviation will increase considerably.
Available capabilities from the Dashboard are: keep original, and furtive display.