The map above shows forest canopy height for the United States in shades of green.

上面的地图通过绿色阴影的深浅标示出美国森林的树冠高度。

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Using a combination of NASA satellite images and laser data, scientists have produced a first-of-its kind map that details the height of the world’s forests.

科学家在综合美国国家航空航天局（NASA）卫星图像和激光（扫描）数据的基础上，绘制出了世界上第一幅展示森林林木高度的地图。

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A standard height map is used to represent the varying height of the surface.

一张标准的高度贴图被用来表现表面多变的高度。

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The first filter that is applied to the height map is a simple Gaussian blur, which the GPU handles with ease, but which -- if left to its own devices -- would simply smooth out all the dramatic extremes in the height map and leave us with a bunch of bland rolling hills.

ENGADGET: Primed: The crazy science of GPU compute Mobile

Instead of randomly generating an entire, playable map, Firaxis's designers only use the CPU to generate a "height map" that contains simple coordinates and 8-bit height values.

ENGADGET: Primed: The crazy science of GPU compute Mobile

So, this approach requires one more layer of effort: converting the height map (or at least its visible tiles) into a "normal map" which is smooth and natural enough to be subjected to lighting effects and then displayed on screen.

ENGADGET: Primed: The crazy science of GPU compute Mobile