If you're looking at it with optical imagery, you might define the edges of clouds another way.

如果你用光学图像来看，你可能会用另一种方式定义云的边缘。

We looked at satellite-based radar and optical imagery, and we lit that region up.

我们查看了基于卫星的雷达和光学图像，然后照亮了那个区域。

Optical imagery satellites, like the U.S. Geological Survey's Landsat, use reflected light to passively take photos from high in the sky.

光学成像卫星，如美国地质调查局的 Landsat，使用反射光从高空被动拍摄照片。