THE ENLARGEMENT AND CLARIFICATION OF THE BESTIARY OF THE AMUR-USSURI PROVINCE OF ROCK ART

В статье представлены результаты работ по редокументированию памятников Нижнего Амура и Уссури (Хабаровский край). Целью работ 2017-2019 гг. было документирование камней и плоскостей с петроглифами современными техническими средствами, а также выявление ранее неизвестных наскальных изображений и поиск утраченных. Для документирования применялась фотосъемка с фотограмметрической обработкой цифровых фотоснимков и формированием текстурированных полигональных моделей камней и поверхностей с петроглифами. В результате камеральной обработки моделей было выявлено 29 неизвестных ранее петроглифов и существенно уточнены контуры 17 изображений. В статье представлены новые данные о зооморфных изображениях в пределах пункта 2 памятника Сикачи-Алян. The paper presents results of the work on re-documenting sites in the Lower Amur and the Ussuri region (Khabarovsk region). The aim of the activities carried out in 2017-2019 was to document boulders and surfaces carrying petroglyphs with the use of modern technical means and identify rock drawings unknown before, as well as search for lost drawings. Documenting was based on photographing with photogrammetric processing of digital photos and development of textured polygonal models of boulders and surfaces with petroglyphs. The desk processing of the boulder models revealed 29 earlier unknown petroglyphs and clarified outlines of 17 drawings. The paper provides new data on zoomorphic images within location 2 at Sikachi-Alyan.

An interference discrimination method for assembly sequence planning and assembly simulation

Purpose The purpose of this paper is to discriminate fake interference caused by polygonal approximation so as to achieve accurate assembly sequence planning and assembly simulation. Design/methodology/approach An approximation zone model is proposed to formulate polygonal approximation. Fake interference is discriminated from hard interference by evaluating if polygonal models intersect within corresponding approximation zones. To reduce the computation, the surface-surface, surface-end face and end face-end face intersection test methods have been developed to evaluate the intersection and obtain collision data. An updated collision detection algorithm with this method is presented, which is implemented by a system named AutoAssem. Findings This method has been applied to a set of products such as a valve for assembly interference matrix generation, static and dynamic collision detection. The results show that it ensures the accuracy of assembly sequence planning and assembly simulation for polygonal models. Practical implications This method facilitates assembly design in the virtual environment with polygonal models. It can also be applied to computer aided design systems to achieve quick and accurate collision detection. Originality/value Fake interference between polygonal models may result in serious errors in assembly sequence planning and assembly simulation. Assembly zone model and novel polygon intersection verification methods have been proposed to effectively tackle this problem. Compared to current methods, this method considers valid penetration direction and approximation difference, does not need to process complicated auxiliary data and can be easily integrated with current collision detection methods.

Adaptive Rendering of Dynamic 3D Scenes

Rendering of dynamic 3d scenes is challenging because it is impossible to perform preprocessing to merge and simplify polygonal models, to precalculate visibility information. The dynamic behavior of objects (visibility change, movement) is causing command buffers rebuilding and rejecting of invisible objects often does not result in performance gains. We propose an adaptive method for visualizing dynamic scenes, which selects the most efficient method for recording and using command buffers and the number of hardware occlusion queries. Proposed adaptive method is based on the performance model, which performs an estimation of the execution time of the main stages of forward rendering. Testing results of the proposed method showed its effectiveness when rendering large dynamic scenes.

A Low-Complexity Region-Based Authentication Algorithm for 3D Polygonal Models

This study proposes a low-complexity region-based authentication algorithm for three-dimensional (3D) polygonal models, based on local geometrical property evaluation. A vertex traversal scheme with a secret key is adopted to classify each vertex into one of two categories: embeddable vertices and reference vertices. An embeddable vertex is one with an authentication code embedded. The algorithm then uses reference vertices to calculate local geometrical properties for the corresponding embeddable vertices. For each embeddable vertex, we feed the number of reference vertices and local properties into a hash function to generate the authentication code. The embeddable vertex is then embedded with the authentication code, which is based on a simple message-digit substitution scheme. The proposed algorithm is of low complexity and distortion-controllable and possesses a higher and more adaptive embedding capacity and a higher embedding rate than most existing region-based authentication algorithms for 3D polygonal models. The experimental results demonstrate the feasibility of the proposed algorithm.