实现地形的部分主要都是改etm实现的。

Mainly to achieve some of the terrain changed ETM achieve.

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实验结果表明该模型能实现地形场景的实时浏览，提高地形场景的绘制效率。

The experiments show that and the real time dynamic browsing is achieved , thus the performance of terrain rendering is improved greatly.

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利用MAPGIS实现地形图数字化是获取空间地理信息数据的主要手段之一，而图形数字化过程中会产生各种类型的误差。

To implement topographic map digitalization by means of MAPGIS is one of main means of getting spatial geographic information data, and that digitalization could bring out diversified sorts of errors.

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