关于百度地图缩放级别

百度地图自身有17个级别，如下：

{"20m","50m","100m","200m","500m","1km","2km","5km","10km","20km","25km","50km","100km","200km","500km","1000km","2000km"}  

但是，提供的开发包只支持16个级别， Level: 3~18, 比例尺如下：

{"50m","100m","200m","500m","1km","2km","5km","10km","20km","25km","50km","100km","200km","500km","1000km","2000km"}