Watertight surface creation by using ¡® Mesh&Curves ' option (with pure untrimmed surface)

Purpose:

In this tutorial, we will show how to create watertighted surface (multiple surfaces) from mesh by using option ¡® Mesh&Curves ' . We will create all the surfaces as untrimmed surface (quad face). Using untrimmed surface, the continuity transition along surface boundary line can reach exact G0 continuity and numberical G1 continuity (such as the maximum tangent angle is smaller than 0.5 degree), this means that we will create watertighted surface over the mesh model.

To create multiple surfaces from mesh, we need to do two main steps:

Step 1: create a curve network on the selected mesh by using option ¡® Sketch on mesh ' in ¡® Create Bspline Curve ' ;

Step 2: create multiple surfaces from mesh by using option ¡® Mesh&Curves ' in ¡® Fit from pnts/mesh ' .

In the following picture, we showed the original mesh model, the curve network (curves and vertexs) and the surfaces created from the mesh.

 

mesh model, curve network and surfaces

2.5.1 Create a curve network on the selected mesh by using option ¡® Sketch on mesh ' in ¡® Create Bspline Curve ' .

Step 1:

Click menu ¡® Geometry->Curve->Bspline Curve ' or icon , a dialog will show. Since we want to create only one curve segment by selecting several nodes or points, we set checkbox Multi-Curves to be unchecked.

Sketch on mesh in Curve creation

 

Step 2

Create first curve. Click ShadeElem icon to set the mesh displayed in shade mode. Shade mode can help us see mesh feature line clearly, so we select several nodes along feature line to create curve. Fig 2.5.4 shows the first curve created by selecting 4 nodes.

create first curve by selecting nodes

 

 

Step 3

Create second curve. In order to let second curve connect with first curve, we select the last node of the first curve as start point, then end the second curve on another new node. The second curve captures mesh feature line on another direction.

create the second curve

 

Step 4

Continue to create the 3 rd curve. In order to get good curve connectivity, we select the last node of the second curve as start point of the 3 rd curve. In our later operation, we always start the new curve by selecting any end node of the existing curves and end the new curve at another new node or end point of the existing curves . This operation will help us keep our curve network good connectivity (no gap tolerance on their intersection poisition).

create the 3 rd curve

 

Step 5

Create the 4 th curve. Select the last node of the 3 rd curve as start point and end this curve on the first node of the first curve. So we get a curve network with 4 curves. A untrimmed surface will generate from them.

create the 4th curve

Step 6

Continue to create other curves, we get a curve network which is defined on the mesh.

 

curve network

2.5.2 Create multiple surfaces from mesh by using option ¡® Mesh&Curves ' in ¡® Fit from pnts/mesh '

Step 7

Click menu Geometry->Surface->Fit from pnts/mesh or icon , and choose option ¡®Surface from Mesh&Curves' .

Step 8

Click checkbox Mesh to select the mesh model bypart . Click checkbox Boundary curves for surface to select all the curves which are created in above steps.

Step 9

Click button Layout , the initial surfaces will generate. If the initial surfaces are created successfully, Fit button will be enabled, otherwise, it is still disabled.

 

previewed surface

 

Step 10

Set Max Tol = 0.1 , click Fit button , the initial surfaces will be updated. Apply button will be activated.

Step 11

Click Apply button, the updated surfaces will be added into database.

 

final surface