Google Earth Engine（GEE）——表达式波段计算：如何按照自己的公式设立波段运算以EVI增强型植被指数为例

expression(expression, map)

Evaluates an arithmetic expression on an image, possibly involving additional images.

The bands of the primary input image are available using the built-in function b(), as b(0) or b('band_name').

Variables in the expression are interpreted as additional image parameters which must be supplied in opt_map. The bands of each such image can be accessed like image.band_name or image[0].

Both b() and image[] allow multiple arguments, to specify multiple bands, such as b(1, 'name', 3). Calling b() with no arguments, or using a variable by itself,