本文主要是通过算法计算slope和自己按照核函数去计算slope查看两者之间的差异
这里面有几个属性需要了解下：
ee.Kernel.fixed(width, height, weights, x, y, normalize)
创建内核：设定长和宽，权重，x，y上的偏移位置，也就是回归左下角一般默认，将内核值归一化，使其和为1
Creates a Kernel.
Arguments:
width (Integer, default: -1):
The width of the kernel in pixels.
height (Integer, default: -1):
The height of the kernel in pixels.
weights (List):
A 2-D list of [height] x [width] values to use as the weights of the kernel.
x (Integer, default: -1):
The location of the focus, as an offset from the left.
y (Integer, default: -1):
The location of the focus, as an offset from the top.
normalize (Boolean, default: false):
Normalize the kernel values to sum