Digital Elevation Model (DEM) records topographic fluctuation changes and in which it contains various topographic construct information including valley lines and ridge lines.

数字高程模型(dem)是记录地形起伏变化的资料，当中蕴含着各种地形地貌的结构信息，其中包括山谷线和山脊线。

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The base, in an eastern Afghanistan valley, was surrounded by ridge lines where the insurgents were able to fire down at U.S. and Afghan troops.

CNN: Afghan insurgents pushed into U.S. base, official says

Mr. ZEV YAROSLAVSKY (Supervisor, Los Angeles County): Where we have tried to protect the ridge lines of the mountains from gaudy, ugly and defiling developments where the occupant of the home would have a 360-degree view, but that the rest of the world would have to look at that gaudy building.

NPR: Calif. Voters Weigh Eminent Domain Ballot Proposal

The dramatic contrasts of tone and scale, the sweeping lines of the ridge, the well-tracked path to the empty summit all add up to an arresting image, a strangely beautiful world where humans don't quite belong but yet intend to tread.

WSJ: Photographic Balancing Acts | Swiss Alpine Museum | He Cut a Fresh Path in Mountain Photography | By Michael J. Ybarra