基于开源高程数据api增加 ，原地址 https://open-elevation.com
Open-Elevation 类似免费开源的 [Google Elevation API] (https://developers.google.com/maps/documentation/elevation/start)
API 文档 [available here] (https://github.com/yihui8776/elevationServerTerrain/tree/main/docs/api.md)