Al-Rafidain Engineering Journal (AREJ) Vol.26, No.2, October 2021, pp.300-308 Al-Rafidain Engineering Journal (AREJ) Vol.26, No.2, October 2021, pp.300-308 Evaluation of Hidden Surface Removal Methods Using Open GL * Remote Sensing Center, University of Mosul ** Computer Engineering Department, Collage of Engineering, University of Mosul Received: 2/2/2021 Accepted: 14/3/2021 ABSTRACT The research aims to address one of the complex problems that may be encountered when generating computer images for three-dimensional (3D) objects, which is the hidden surface detection and elimination. Several methods have been devised, through the last three decades, to solve this problem. However, the most popular methods used widely nowadays are depth or Z-Buffer (ZB) and Binary Space Partition Tree (BSPT). The first method (ZB) is very simple and more general but requires additional memory to store depth values in addition to intensity. On the other hand, (BSPT) method is more complex to implement but requires memory for pixel intensity only. Modelling graphical database in a binary tree make the dealing with parts of the database feasible. This is so important for clipping a part or more of the database when outside the viewing zone. The focus of this paper is to study these two methods, design an algorithm to implement each of them. After that a reasonable procedure is to found and applied for testing the performance of each of the two methods using exactly the same graphic load. A step by step increase of this load should be possible so that the behavior of the execution time at different complexity level and on average bases can be reported. The outcome results of the two methods should be compared and a recommendation to use which one of them is to be concluded [1]. Since one of the most popular graphics library which is being used during the last ten years and nowadays is the Open Graphic Library( OpenGL) from(Silicon Graphic Incorporation (SGI)[2], the algorithms of this work are implemented and the related software is carried out using this library with visual C platform. Keywords: Hidden Surface. Back Face. Pixel. BSPT. ZB. OpenGL This is an open access article under the CC BY 4.0 license (http://creativecommons.org/licenses/by/4.0/). https://rengj.mosuljournals.com ============================================================================= 1. INTRODUCTION Computer has become a powerful tool for the rapid and economical production of pictures. There is virtually no area in which graphical displays cannot be used to some advantage, and so it is not surprising to find that the use of computer graphics is so widespread [3]. Although early applications in engineering and science had to rely on expensive and cumbersome equipment, advances in computer technology have made interactive computer graphics as a practical tool. Computer graphic have attracted the attention of many researchers in many fields like engineering, medicine , business, industry, government, art, entertainment, advertising , education and training [4] . Several techniques are used to solve the hidden surface problem which are the painter s’ algorithm, Z-buffer, scan line, ray casting, depth sort, and BSPT. Among the most important of these technologies, BSPT and ZB are of the algorithms to rapidly generate realistic images of 3-D scenes composed of polygons. The BSP algorithm and z-buffer are used for solving the hidden surface problem [6] . OpenGL is a low-level graphic library specification, which makes available to the programmer a major of geometric primitives: points, lines, polygons, images, and bitmaps. It provides a set of commands that allow the specification of geometric objects using the Lubna Muzahim Saeed lubnasaeed81@gmail.com Fakhrulddin H. Ali fhazaa@uomosul.edu.iq