DEM应用在WW的三维表现中占有很重要的位置,跟影像数据同等重要!幸好影像和DEM的加载和处理原理上几乎一致,对基于WW搞GIS三维开发来说是件好事,理解好任何一种,另一种触类旁通!前一篇,主要从功能上做了简单入门介绍,该篇将从代码级别分析WW内置的SRTM的DEM数据加载和应用,下一篇讲从二次开发角度上讲解如何处理、配置自己的影像和DEM数据。呵呵,因为DEM部分很重要,且是放假期间我也有时间,争取篇篇精彩!
两个缩写词介绍:因为这两个缩写词常出现,知道是什么缩写,就不觉得神秘啦!
SRTM:The Shuttle Radar Topography Mission (SRTM) obtained elevation data on a near-global scale to generate the most complete high-resolution digital topographic database of Earth. SRTM consisted of a specially modified radar system that flew onboard the Space Shuttle Endeavour during an 11-day mission in February of 2000.
NLT:NASA Learning Technologies.
我从BMNG.cs为例入手研究DEM的使用,当然研究瓦片影像也该从此入手,但,今天影像不是我们关注的重点。现在正式步入主题,跟我一起分析和学习代码吧!
BMNG.cs类144行构造函数中代码,
WorldWind.NltImageStore imageStore = new WorldWind.NltImageStore(String.Format("bmng.topo.2004{0:D2}", i + 1), "http://worldwind25.arc.nasa.gov/tile/tile.aspx");
imageStore.DataDirectory = null;
imageStore.LevelZeroTileSizeDegrees = 36.0;
imageStore.LevelCount = 5;
imageStore.ImageExtension = "jpg";
imageStore.CacheDirectory = String.Format("{0}\\BMNG\\{1}", m_WorldWindow.Cache.CacheDirectory, String.Format("BMNG (Shaded) Tiled - {0}.2004", i + 1));
ias = new WorldWind.ImageStore[1];
ias[0] = imageStore;
m_QuadTileLayers[0, i] = new WorldWind.Renderable.QuadTileSet(
String.Format("Tiled - {0}.2004", i + 1),
m_WorldWindow.CurrentWorld,
0,
90, -90, -180, 180,
true,
ias);
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