Model functionalities exemplified for membrane geometries. (a) shows a bacterial membrane where the user defines an area of interest in the tomogram browser and a group of seed points (in red). (b) is one of the user interfaces attached to the membrane model, offering a montage view of the area of interest. Each slice represent a z-cut of the tomogram for different, equispaced values of z. Seed points entered by the user on the first section are used to automatically compute points belonging to the membrane in the next section. The GUI allows the immediate evaluation and correction of the automatic detection. (c) The detected set of points. These are processed by the workflow GUI in (d) to parameterize the membrane as a smoothly triangulated surface, which is then used to define a regular distribution of points, each of which is provided with an initial orientation normal to the membrane, as shown in (e).