Project Refine

 

The Refine project provides an interface to some interactive refine methods, the most important one is the curvature dependent refinement. The methods for selecting edges for refinement are defined on Adapt2d, the refine methods themselves are based on the methods described in section 6.3.3.4 and provide special support for Surfaces.

 
Figure 8.23: User-Interface for the Refine Project

Refining a step of a Surface changes the discretization of the step itself and possibly some neighbour steps therefore the refine methods have to be applied carefully, please read the next section before you use them.

There are three different display methods (you have to press first, then the button) for selecting which edges should be refined. The display is switched to grid mode and the geometry is rendered in green, the edges that will be refined are drawn in red and the edges that will be inserted are drawn in yellow (the result can differ slightly from what you see because the refine algorithm may add some correction steps).

With this method triangles in regions of high Gaussian curvature can be refined (see the next section for an example), all edges with a curvature higher than the value of the ruler added to the option menu are selected for refinement. The curvature of an edge is computed from the angle(s) between the surface normals at opposite vertices of the triangle(s) the edge belongs to (the normal rotation along and if possible across the edge).

Refine the triangles with a boundary edge with a length greater than the value of the ruler added to the option menu. As for the other methods the longest edge of the triangle is selected for refinement, therefore it may be necessary to refine triangles twice to really refine the boundary edges.

Refine all triangles which are inside a ball and have an edge longer than the selected sidelength value. The center of the ball can be changed by pressing the button and picking a point in the graphics window.

Be careful: These methods replace the "set-rfc-field-send" method with their own versions, if you want to use the original method after using one of these methods you must restore adapt2d_set_rfc_field_send as "set-rfc-field-send" method.

Refining all steps of a Surface instance with is only possible if they all have the same discretization, therefore you can only use this method before methods like and which change the discretization locally. only refines the current step of a Surface instance (and its neighbour steps), the objects of the steps are split if necessary (see the next section for further information).

In some cases refining several triangulations with the same discretization using the same refine field results in triangulations with different discretizations. This can only happen if the refine algorithm has to add correction steps for refining the marked edges and if corresponding triangles have different longest edges, therefore this problem is more likely to occur when a whole sequence of steps is refined with . You can still continue working with these triangulations, but you won't be able to interpolate them or to refine them again.