Global hierarchical detail network three-dimensional terrain image overlaying method

Abstract

The invention relates to a global hierarchical detail network three-dimensional terrain image overlaying method which includes the following steps. Firstly, a global uniform texture locator system which can meet a certain requirement is built up. Secondly, in terrain hierarchical models, defined model top texture locators in a global uniform texture locator system are arranged on model tops when models of terrain blocks are built up. Thirdly, when expression of the terrain hierarchical model is drawn, the global uniform texture locators of the model tops can respectively converted to be multiple texture locators which aim at terrain texture and overlaid images. The problem that synchronous conversion in a multiple space is hard is solved. Fourthly, in time of sampling texture, image sources of pixel texture are compared to complete uniform drawing of the overlaid images and the terrain texture when the texture is sampled. The global hierarchical detail network three-dimensional terrain image overlaying method can efficiently achieve overlaying of images which are completely sewed up with terrains without extra models and the problem of real-time interaction and expression of the overlaid images is solved.

Description

technical field [0001] The invention relates to the technical field of computer graphics and large-area terrain three-dimensional simulation, in particular to a method for superimposing three-dimensional terrain images of global hierarchical detail grids. technical background [0002] Google Earth, developed by Google, provides a function of superimposing images on 3D terrain. Google Earth uses high-end pixel-level ClipMap technology to achieve global 3D expression. This technology can easily overlap images and terrain. position, and can conveniently realize image scaling, rotation and shifting operations. However, since the vast majority of global 3D terrain modeling is still expressed in the easier-to-grasp terrain block level-of-detail model (LoD), it becomes extremely difficult to implement such a seemingly simple function in this level-of-detail mode , so far, have not seen the relevant application of new product examples, the reasons for the difficulties are as follow...

AI Technical Summary

Problems solved by technology

However, its shortcomings are not only due to the fact that the additional terrain representation model has a certain degree of impact on the efficiency of the entire global terrain representation, the more important issue is how to ensure that the newly established image overlay model can be completely superimposed on the original terrain surface , we know that if we want to completely coincide with the original terrain surface, there is only one situation, that is, all the vertices of the new model are completely consistent with the corresponding vertices of the original terrain model, but we must ensure that this consistency is completely consistent in the multi-layer terrain representation It is impossible to use a regular grid model, because the grid spacing of terrain blocks in different layers is inconsistent. Even if the efficiency loss is not considered, it is expressed in a triangular network. How to extract the terrain block coverage vertex data from the corresponding terrain? It is an extremely complicated problem to deal with the vertex sampling offset caused by image rotation and how to quickly respond to image interaction in real time to build a corresponding model.

[0005] According to our understanding, there are almost no successful cases of the former segmentation thinking, and the latter model thinking of independent expression can only be applied to static, regular image stacking in the true north direction, such as the realization in World Wind , and the problem of overlapping gaps cannot be avoided

Images