The proposed laser pointer technique uses two spots on a screen for interaction with virtual environments and presentations. The spots are produced by splitting an infrared laser beam.

The proposed multiple-point interaction technique realizes direct interaction and control in a virtual environment and presentation. The device for interaction is constructed on the basis of the infrared (IR) laser which is invisible for a human eye and does not interfere with the visual channel of a presentation, since there can be no coincidence of the color of the infrared laser and the visible object on the screen.The special designed optical scheme splits a laser beam into three with a small angle of divergence. As a result we receive the three IR spots on the screen.The coordinates of the laser spots received from the infrared camera are interpreted as a position of the (pointer) cursor after the mathematical processing which is displayed with the help of the projection system and can be interpreted as commands of the application control.

The purpose of the article is the consideration of the problem of ambiguity over the faces arising in the Marching Cube algorithm. The article shows that for unambiguous choice of the sequence of the points of intersection of the isosurface with edges confining the face it is sufficient to sort them along one of the coordinates. It also presents the solution of this problem inside the cube. Graph theory methods are used to approximate the isosurface inside the cell.>