Boundaries can be found from the mesh using the function 'findBoundaries'. It has the following syntax
boundaries = findBoundaries(mesh, querystring, optional arguments);
The return value is a vector. The vector holds the indices of boundaries (a triangle segment).
circle = findBoundaries(mesh, 'direction', [line_startx line_starty line_startz], [line_endx line_endy line_endz])
Now circle contains the the indices of the triangles of a circular region in the boundary. The circle is defined by a cylinder that intersects the boundary. The cylinder is defined by a line given as parameter.
A detailed documentation of the optional arguments and the query strings are given below.
| Query string | Description | Arguments | Argument description | Row length |
| 'direction' | Finds elements that are contained in a region defined by a cross sectional shape and a line that intesects it in the middle. The line starts from origin and goes to waypoint. | origin | Origin point of the line | 3 |
| waypoint | Direction vector of the line | 3 | ||
| radius | Width of the line segment | 1 | ||
| shape: circle (default), box, arbitrary | Cross-sectional shape of the region | |||
| points (optional) | If an arbitrary shape is defined, this specifies its coordinates | |||
| 'halfspace | Returns the elements within a halfspace spanned by a location vector and a plane normal | location | Location of the center of the plane (point that the plane intersects) | 3 |
| normal | Normal of the plane. Elements in the direction of normal will be selected. | 3 | ||
| 'inverse | Inverses the selection | selection | Array that contains the indices of the boundary that is selected | number of elements in the selection |
| 'location | Finds a boundary nearest to a user specified location | location | The location | number of points specified |
| 'sphericalregion' | Finds a boundary that is contained within a subspace defined by a segment of the unit sphere | starttheta | Starting polar angle | 1 |
| startphi | Starting azimuthal angle | 1 | ||
| endtheta | Ending polar angle | 1 | ||
| endphi | Ending azimuthal angle | 1 |