trig point       
noun [ C ]  geography UK specialized uk/ˈtrɪɡ ˌpɔɪnt/ us/ˈtrɪɡ ˌpɔɪnt/ (also triangulation point, /traɪˌæŋ.ɡjəˈleɪ.ʃən ˌpɔɪnt/ /traɪˌæŋ.ɡjəˈleɪ.ʃən ˌpɔɪnt/)
 三角测量点
a point at the top of a hill or mountain, usually marked by a small stone or concrete structure, used in surveying (= measuring and recording details of the distances, heights, etc. of areas of land)
  Ward Stone has a trig point and is one of the highest points locally, providing superb views. 沃德石山上有一个三角测量点,是当地最高点之一,景色极好。 
 - More examples
 - Turn left and walk toward the trig point and summit cairn.
 - We sat with our backs against the trig point and gazed down like gods on the coastal plain of Thassos.
 - The other, less steep, ridge leads directly to the summit cairn and trig point at 3,442ft/1,049m.
 - He was so taken in by the view that he stepped back from the trig point and disappeared over the edge of the crag that crowns the top.