基于跨越式HLOD的倾斜摄影模型快速可视化方法

Rapid Visualization Method of Oblique Airborne Photogrammetry Model Based on Skipping HLOD

为了在浏览器上实现大规模倾斜摄影模型的可视化,针对传统分层层次细节模型(HLOD)在绘制过程中需要逐级遍历所需分辨率之前的每一级别分辨率的瓦片,逐步细化到所需分辨率的局限性,参考MRF数据格式设计一种适合网络传输和应用的三维模型数据格式,提出一种面向具有静态LOD三维模型数据的快速绘制方法,可以使基于Web GL的三维地学浏览器引擎在加载模型瓦片数据时,根据视点位置和屏幕空间误差动态越过无需绘制的层次,实现跨越式调度和渲染.实验表明,该方法配合内外存调度、遮挡剔除等加速策略可以有效地降低浏览器端的下载数据量,减少网络请求和内存占用,同时减轻客户端的渲染压力.

In order to realize visualization of large-scale oblique airborne photogrammetry 3D model in the browser, the traditional hierarchical levels of detail model （HLOD） in the process of drawing to progressively traverse required for each level of resolution before the resolution of tiles, stepwise refinement to the limitations of the required resolution. This paper refers to MRF data format to design a 3D model data format for online transmission and application and puts forward a method for fast rendering with static LOD 3D model data. This method can make the 3D WebGL browser engine load tile model data skipping the unmapped hierarchy dynamically according to the viewpoint location and screen space error realizing the leap-forward scheduling and rendering. Experiments show that the method with internal and external memory scheduling and occlusion culling strategy can reduce the downloads through browser and network requests and memory, while reducing the pressure of the client.