Gauss Point presentations use primitives to visualize the value of the results obtained during calculations so that the color and relative size of the points depend on each component of a vector, tensor or matrix (e.g. scalar and module for vectors). Of course, the size of primitives in the Viewer also depends on their location within the 3D scene. At a given computed size, a primitive will be bigger when it is close to the camera and smaller at a distance.
There are three Basic primitive types which can be used in Gauss Points presentations: Point Sprites, Open GL Points and Geometrical Spheres.
Each Point Sprite is visualised in 3D Viewer with two 16*16 textures: Main texture which defines the shape of the point sprite and Alpha Channel Texture which defines the transparency of the point sprite. By default Salome suggests textures defined in the Preferences, however you can browse for other .bmp, .png or .jpg files to be used as textures.
Alpha Channel Threshold defines the level of transparency ranging from 0 to 1.
The default sizes of point sprites are computed by the system, therefore, these parameters cannot be defined in the preferences, however, the Maximum Size of the point sprite is limited (Clamp) so that the whole scene would remain visible if the user applies a high zoom factor. Maximum Size corresponds to the maximum size of a point sprite during rendering whatever is the magnification of the point or the zoom of the view. Technically, it corresponds to setting up a clamp in the vertex shader. The Size is measured in pixels and belongs to the interval from 1 to 512.
OpenGL Points don't use any files as textures, displaying results as simple OpenGL points, so the only parameter relevant to them is the Maximum Size.
Geometrical Spheres display results using a standard sphere with a number of faces be defined thought a Resolution parameter. By default the Resolution is set to 8. This number corresponds to the Latitude and Longitude definitions of a VTK sphere. The Number of Faces parameter is equal to the total number of points in the scene when no segmentation cursor is used or number of points within the cursor when a segmentation is in progress, multiplied by the number of faces of one Sphere in the current resolution. This value computed by the system using the formula: NbrFaces = 2*Resolution x [Resolution-2] and displayed to the end-user for information purpose.
In the pictures you can see the spheres with Resolution of 8:
and 6:
Notify when number of faces exceeds prompts the user by a dialog to continue or to cancel the display operation if the number of faces is greater than the number defined in the menu.