ALGORITHMS FOR ESTIMATION OF SCENE
OBJECTS VISIBILITY IN SIMULATION TRAINING OF BASIC LAPAROSCOPY SKILLS 

Kuz'min Andrey Viktorovich, Candidate of engineering sciences, associate professor, sub-department of theoretical and applied mechanics, Penza State University (40 Krasnaya street, Penza, Russia), flickerlight@inbox.ru
Milyutkin Mikhail Grigor'evich, senior developer, SEC “Magenta Technology” (146 Samarskaya street, Samara, Russia), milutkin@magenta-technology.ru
Cherepanov Aleksey Sergeevich, senior developer, SEC “Magenta Technology” (146 Samarskaya street, Samara, Russia), cherepanov@magenta-technology.ru
Ivashchenko Anton Vladimirovich, Doctor of engineering sciences, associate professor, project manager, SEC “Magenta Technology” (146 Samarskaya street, Samara, Russia), ivashenko@magenta-technology.ru
Kolsanov Aleksandr Vladimirovich, Doctor of medical sciences, professor, head of sub-department of operative surgery and clinical anatomy with innovation technologies course, Samara State Medical University (89 Chapaevskaya street, Samara, Russia), avkolsanov@mail.ru
Yunusov Renat Rafatovich, Candidate of medical sciences, associate professor, sub-department of operative surgery and clinical anatomy with innovation technologies course, Samara State Medical University (89 Chapaevskaya street, Samara, Russia), avkolsanov@mail.ru 

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Background. The interest in simulation training of the basic laparoscopy skills of laparoscopy surgeons is associated with the prevalence of laparoscopic operations and the possibility for the effective use of modern technology. "Virtual Surgery" is a training system for operative laparoscopy created with the use of upto-date technologies of 3D simulation by a team of scientists and doctors from Samara State Medical University and software developers of Magenta Technology. In simulation of laparoscopic operation of prior importance is that the surgeon gets the visual information from the monitor that demonstrates the image from the endoscopic camera. The student learns to estimate properly the positional relationship of the objects by the flat image from the camera, to control the movements of instruments, to coordinate the interaction of the camera and instruments having them permanently in view. Thus, one of the key tasks of operation process simulation is the estimation of visibility of scene objects.
Materials and methods. The software of the complex is accomplished by the use of up-to-date technologies of simulation of 3D modeling and physical properties of materials: USB HID, DirectInput, SDL, OpenGL, Direct3D, OpenCL, DirectCompute, CUDA, PhysX, Havok. OGRE 3D engine was chosen as the base for visualization. The analysis of the existing methods has shown that the most effective method is the one of occlusion query that is
supported by OGRE 3D engine starting with version 1.8.
Results. The main tasks of the basic laparoscopy skills training connected with the control over the endoscopic
camera and scene objects visibility were analyzed. For successful solution of these tasks the algorithms using OGRE 3D occlusion query were developed. The descriptions of the main steps of using occlusion query as well as the corresponding data structures were given. The results are illustrated by the images of real base skills scenes from the «Virtual Surgery».
Conclusions. The introduced algorithms of using occlusion query solve the tasks of basic skills of laparoscopy training. They are inculcated in the "Virtual Surgery". 

3D simulation, surgery education using simulation, occlusion query, geometrical model, camera, projection, ogre3d. 

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