Google Earth Engine（GEE）——制作一个简易的panel的demo来展示地图

函数：

getDownloadURL(params, callback)

Get a download URL for small chunks of image data in GeoTIFF or NumPy format. Maximum request size is 32 MB, maximum grid dimension is 10000.

Use getThumbURL for RGB visualization formats PNG and JPG.

Returns returns a download URL, or undefined if a callback was specified.

获取GeoTIFF或NumPy格式的小块图像数据的下载URL。最大请求大小为32MB，最大网格尺寸为10000。

对于RGB可视化格式PNG和JPG，使用getThumbURL。

返回 返回一个下载URL，如果指定了回调，则未定义。

Arguments:

this:image (Image):

The Image instance.

params (Object):

An object containing download options with the following possible values:

- name: a base name to use when constructing filenames. Only applicable when format is "ZIPPED_GEO_TIFF" (def