Description

In the solid modeling approach, Pointwise creates models and quilts while importing the initial CAD data. Models are topological CAD entities that allow for watertight meshing over gaps and cracks existent in the underlying geometry. Quilts are meshing regions defined at the CAD level. Furthermore, while a model is a watertight representation of the geometry, quilts are the regions withing the model that hide unnecessary complex topology in the underlying geometry by defining meshing region boundaries. Note that models can be open or closed and they can be assembled into larger models using the command described in this section.

 

Tip: Keep in mind that non-parametric surfaces such as shells cannot be assembled into models.

The Assemble Models command is only available when database surfaces are present. That being said, note that non-parametric surfaces such as shells cannot be assembled into models. Once this condition is met, the Assemble Models command is available regardless of the current selection. However, after the panel is open (image below), only models and database surfaces will be considered and available for further selection.

Assemble Models
Use the tools in the Assemble Models panel to assemble new models.

Entering the Assemble Models command with no database models or database surfaces selected will present the panel shown in the figure above. As surfaces are selected, the total is shown in the table as Surfaces. On the other hand, as models are selected, the total number of models and their corresponding quilts are shown as Models and Quilts respectively. The table also presents the number of Lamina Boundaries (color coded in red) and Manifold Boundaries (color coded in light blue). The former corresponds to surface edges used by exactly one surface. The latter, corresponds to surface edges used by exactly two surfaces.

The Assemble command will become available once a surface, a model, a group of surfaces, a group of models, or a group of surfaces and models is selected. The Assemble command will have the selected entities combined into as few models as possible subject to the Edge Tolerance.

The Edge Tolerance represents the single maximum physical edge distance between two surfaces. Uncheck Use Default to adjust the tolerance if necessary to overcome larger gaps. Note that the default value of this tolerance is calculated as a function of the Model Size tolerance as follows:

Edge Tolerance (default) = Model Size / 106

After the assemble operation is complete, the total number of assembled models is then shown in the table as Models. Use the Clear Assembly command to clear out the current assembled model while leaving the selection active.

 

Tip: If your newly created models overlap where you wish them to be joined, use the Edit, Trim By surfaces command to trim the models against each other and allow them to be joined into a single model.

The simple store geometry shown below will be used to illustrate the assembly process.

Assemble Model Ex 1
A simple database is used to illustrate database model assembly.

Selecting all of the database surfaces for this geometry and clicking Assemble in the panel produces the rendering and the tabulated results show in the figure below.

Assemble Model Ex 2
Rendering changes were performed to reflect the models assembled. The results are tabulated at the top of the Assemble panel.

Note that each resulting model is rendered shaded in a different color for clarity. In this particular case there are five models: one for the body and one for each of the four fins.

Note the light blue edges rendered for all of the original surfaces. These indicate manifold connections between the surfaces; each common edge is used exactly twice between two adjacent surfaces. The table shown in the figure above indicates that there are 24 Manifold Boundaries and 8 Lamina Boundaries. The latter are surface edges used by only one surface. In this case, the fins pass through the body and the open root edges of the fins are free.

If you make the body transparent (see the Attributes section for further details), you will see the fins cutting through it and the red edges indicating Lamina Boundaries as shown in the figure below. It is important to note that each individual surface is converted into a single quilt during model assembly.

Assemble Model Transparency
Making the body transparent, allows you to clearly see the fins cutting through it and their Lamina edges (in red).

Use the options in the Automatic Quilt Assembly frame to have database quilts assembled automatically during the model assemble process. Check on Enable for this functionality to be active. Quilts will be assembled according to the turning Angle. Furthermore, quilts meeting at a common edge with a turning angle smaller than the value specified in the Angle field, will be assembled into a single database quilt.

Also, a turning angle can be specified in the Boundary Angle field so that quilt bounding curves can be joined during the quilt assemble operation. Such curves will be joined where the turning angle at their common end points is smaller than the value entered in this field. Refer to the Quilts section for more information on quilts and assembling them separately.

Assemble Models Autoquilt
Use Automatic Quilt Assembly to create quilts as a post-process of model assembly.

At the bottom of the Assemble Models panel, you will find the Excluded Entities table. This table presents the list of entities that could not be assembled into a single database model. In the particular case shown below, the Entity field indicates that the problematic entity is the model named "TrimSurf-6357-model". Furthermore, the Reason field indicates that this entity is overlapping another database model (i.e. typical case of overlapping surfaces). Select a row in the table and use the Zoom to Selected Entities command to quickly zoom into the appropriate problematic entity.

Assemble Models, Excluded Entities Table
The Excluded Entities table presents a list of entities that could not be assembled into a single model.

Demonstration

Assembling a Watertight Model

Identifying Lamina Boundaries

Removing Model Discontinuities for Meshing