# Split Surfaces by Curvature

This tool analyzes the curvature of the selected surfaces according to a specified angle in degrees. The surfaces with such curvatures are listed with the list of parametric coordinates where this criterion may be satisfied.

By default, not all the parametric coordinates will be always enabled because the analysis is performed taking into account the neighboring surfaces, so more divisions may appear because of the adjacent surfaces. The tool enables only the divisions that provide the angular step.

This tool only takes into account NURBS surfaces, so objects must be exploded (explode command) to be analyzed and meshes must be converted (meshToSurfaces command). Note that meshes are made of almost planar elements, so analyzing its curvature would not have real interest.

The elements and options available in the tool are:

- Angle The reference angle for the curvatures detection.
- Update Button Press it to repeat the identification of the curved surfaces in the selected list. It must be pressed if the Angle is modified.
- Status Indicates if there are curved surfaces or not.
- List of curved surfaces found In case of identifying some curved surfaces, they are separated in this list. The list is updated whenever some of the considered surfaces is removed of the geometry or modified with some opperations such as group, split or boolean operations,...
- Parametric coordinates Table with the U and V coordinates where a curvature deviation has been detected for the selected surface in the list. The detected parametric coordinates can be selected to be visualized in Dash-Blue lines, but only the enabled coordinates are always represented in grey lines.
- SplitSurfaceByIsoparamGrid button The curved surface selected in the list may be split by the isoparam lines corresponding to the parametric points enabled in the U-V tables. The button only can be used when at least one parametric coordinate is enabled.

In the following, an example of a sphere is analyzed to test this tool. Remember that the sphere must be exploded to be analyzed with the tool.

Click on Geometry – Tools – Split Surfaces by Curvature to open the panel.

By selecting all the surfaces of the exploded sphere, the next two test are performed:

- Angle of 30 degrees. Select all the surfaces, insert a curvature angle of 30 degrees and then click on Update button.

As all the surfaces of the sphere has the same shape and a curvature of 90 degrees in each parametric dimension, they are listed with 2 parametric divisions in U and V dimensions each one. The next figure shows the representation of the second surface in the list with all the parametric coordinates on the table enabled and only one of then selected.

- Angle of 20 degrees. Select all the surfaces, insert a curvature angle of 20 degrees and then click on update button.

As all the surfaces of the sphere has the same shape and a curvature of 90 degrees in each parametric dimension, and the selected angle is not a divisor of 90, the curvature of 20 degrees may be different according to the start reference point that is considered. The next figure shows the representation of the second surface in the list with the default parametric coordinates on the table enabled and the disabled ones in V-dimension selected. In this figure is shown that the curvature analysis provides two different solutions the enabled and the disabled divisions.

Click on SplitSurfaceByIsoparamGrid button to finish the example by dividing the surface with the enabled parametric coordinates. After run the command, the list of curved surfaces is updated and the first one is selected, as shown in next figure.