We show how to overcome the single weakness of an existing fully automatic system for acquisition of spatially varying optical material behavior of real object surfaces. While the expression of spatially varying mater...We show how to overcome the single weakness of an existing fully automatic system for acquisition of spatially varying optical material behavior of real object surfaces. While the expression of spatially varying material behavior with spherical dependence on incoming light as a 4D texture(an ABTF material model) allows flexible mapping onto arbitrary 3D geometry, with photo-realistic rendering and interaction in real time,this very method of texture-like representation exposes it to common problems of texturing, striking in two disadvantages. Firstly, non-seamless textures create visible artifacts at boundaries. Secondly, even a perfectly seamless texture causes repetition artifacts due to their organised placement in large numbers over a 3D surface. We have solved both problems through our novel texture synthesis method that generates a set of seamless texture variations randomly distributed over the surface at shading time. When compared to regular 2D textures, the inter-dimensional coherence of the 4D ABTF material model poses entirely new challenges to texture synthesis, which includes maintaining the consistency of material behavior throughout the 4D space spanned by the spatial image domain and the angular illumination hemisphere. In addition, we tackle the increased memory consumption caused by the numerous variations through a fitting scheme specifically designed to reconstruct the most prominent effects captured in the material model.展开更多
结合遗传算法和模拟退火算法,构造出具有全局搜索优化特性的遗传模拟退火算法。根据空间目标表面的多组多角度双向反射分布函数(bidirectional reflectance distribution function,BRDF)实验数据和统计模型,获得样片BRDF五参数模型参数...结合遗传算法和模拟退火算法,构造出具有全局搜索优化特性的遗传模拟退火算法。根据空间目标表面的多组多角度双向反射分布函数(bidirectional reflectance distribution function,BRDF)实验数据和统计模型,获得样片BRDF五参数模型参数值及2D、3D的BRDF分布。比较基本遗传算法和遗传模拟退火算法在迭代次数、计算时间、参数值及精度等之间的差异并分析其原因。遗传模拟退火算法更适用于BRDF的统计建模。展开更多
The ever-increasing demand for oil and gas has driven its exploration in rather extreme conditions. In Lamu offshore, which is hitherto underexplored, most of the wells already drilled turned out dry save for a few we...The ever-increasing demand for oil and gas has driven its exploration in rather extreme conditions. In Lamu offshore, which is hitherto underexplored, most of the wells already drilled turned out dry save for a few wells with hydrocarbon shows despite the promising reservoir properties and related geological structures. This, therefore, necessitated a source rock evaluation study in the area to ascertain the presence and potential of the source rock by integrating the geochemical data analysis and petroleum system modeling. The shallow Lamu offshore source rock quantity, quality, and maturity have been estimated through the determination of the total organic carbon (TOC) average values, Kerogen typing, and Rock-Eval pyrolysis measurements respectively. Geochemical data for Kubwa-1, Mbawa-1, Pomboo-1, and Simba-1 were evaluated for determining the source rock potential for hydrocarbon generation. Petroleum system modeling was applied in evaluating geological conditions necessary for a successful charge within a software that integrated geochemical and petrophysical characterization of the sedimentary formations in conjunction with boundary conditions that include basal heat flow, sediment-water interface temperature, and Paleo-water depth. The average TOC of 0.89 wt % in the study area suggests a fair organic richness which seems higher in the late cretaceous (0.98 wt %) than in the Paleocene (0.81 wt %). Vitrinite reflectance and T<sub>max</sub> values in the study area indicate the possible presence of both mature and immature source rocks. Type III Kerogen was the most dominant Kerogen type, and gas shows are the most frequent hydrocarbon encountered in the Lamu Basin with a few cases registering type II/III and type II. The charge properties (i.e. Temperature, transformation ratio, and Vitrinite reflectance) over geologic time at each of the wells have been estimated and their spatial variation mapped as seen from the burial history and depth curves overlaid with temperature, transformation ratio, and Vitrinit展开更多
基金partially supported by the European project MAXIMUS (No. FP7-ICT-2007-1-217039)the German Federal Ministry for Economic Affairs and Energy project Cult Lab3D (No. 01MT12022E)
文摘We show how to overcome the single weakness of an existing fully automatic system for acquisition of spatially varying optical material behavior of real object surfaces. While the expression of spatially varying material behavior with spherical dependence on incoming light as a 4D texture(an ABTF material model) allows flexible mapping onto arbitrary 3D geometry, with photo-realistic rendering and interaction in real time,this very method of texture-like representation exposes it to common problems of texturing, striking in two disadvantages. Firstly, non-seamless textures create visible artifacts at boundaries. Secondly, even a perfectly seamless texture causes repetition artifacts due to their organised placement in large numbers over a 3D surface. We have solved both problems through our novel texture synthesis method that generates a set of seamless texture variations randomly distributed over the surface at shading time. When compared to regular 2D textures, the inter-dimensional coherence of the 4D ABTF material model poses entirely new challenges to texture synthesis, which includes maintaining the consistency of material behavior throughout the 4D space spanned by the spatial image domain and the angular illumination hemisphere. In addition, we tackle the increased memory consumption caused by the numerous variations through a fitting scheme specifically designed to reconstruct the most prominent effects captured in the material model.
文摘结合遗传算法和模拟退火算法,构造出具有全局搜索优化特性的遗传模拟退火算法。根据空间目标表面的多组多角度双向反射分布函数(bidirectional reflectance distribution function,BRDF)实验数据和统计模型,获得样片BRDF五参数模型参数值及2D、3D的BRDF分布。比较基本遗传算法和遗传模拟退火算法在迭代次数、计算时间、参数值及精度等之间的差异并分析其原因。遗传模拟退火算法更适用于BRDF的统计建模。
文摘The ever-increasing demand for oil and gas has driven its exploration in rather extreme conditions. In Lamu offshore, which is hitherto underexplored, most of the wells already drilled turned out dry save for a few wells with hydrocarbon shows despite the promising reservoir properties and related geological structures. This, therefore, necessitated a source rock evaluation study in the area to ascertain the presence and potential of the source rock by integrating the geochemical data analysis and petroleum system modeling. The shallow Lamu offshore source rock quantity, quality, and maturity have been estimated through the determination of the total organic carbon (TOC) average values, Kerogen typing, and Rock-Eval pyrolysis measurements respectively. Geochemical data for Kubwa-1, Mbawa-1, Pomboo-1, and Simba-1 were evaluated for determining the source rock potential for hydrocarbon generation. Petroleum system modeling was applied in evaluating geological conditions necessary for a successful charge within a software that integrated geochemical and petrophysical characterization of the sedimentary formations in conjunction with boundary conditions that include basal heat flow, sediment-water interface temperature, and Paleo-water depth. The average TOC of 0.89 wt % in the study area suggests a fair organic richness which seems higher in the late cretaceous (0.98 wt %) than in the Paleocene (0.81 wt %). Vitrinite reflectance and T<sub>max</sub> values in the study area indicate the possible presence of both mature and immature source rocks. Type III Kerogen was the most dominant Kerogen type, and gas shows are the most frequent hydrocarbon encountered in the Lamu Basin with a few cases registering type II/III and type II. The charge properties (i.e. Temperature, transformation ratio, and Vitrinite reflectance) over geologic time at each of the wells have been estimated and their spatial variation mapped as seen from the burial history and depth curves overlaid with temperature, transformation ratio, and Vitrinit
