dem_earth_curvature_drop — DEM geodesy op

• Data kinds: none → measurement (an op determined by its arguments alone — it takes no image or data input)

• Call: import demops; demops.dem_earth_curvature_drop(distance_m, refraction=0.13) (or opsdem.get("dem_earth_curvature_drop"))

Usage

> This operator's description has not been translated yet. The original text follows as it is.

見通し計算の地球曲率落ち [m]。`(1 - k) d^2 / (2 R)`。

遠くの地面は地球の丸みぶん下がって見え、大気屈折はそれを一部打ち消します。

標準大気(`k = 0.13`)での目安:

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距離 曲率のみ 屈折込み

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1 km 0.078 m 0.068 m

5 km 1.962 m 1.707 m

10 km 7.848 m 6.828 m

30 km 70.63 m 61.45 m

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30 km 先の見通しでは 60 m 以上下がるので、平面として扱った可視領域は

その距離では意味を持ちません。`refraction` は標準大気の慣行値であって

定数ではない —— 夜間の逆転層では負にも 0.25 にもなります。

Detailed usage guide

• dem_terrain_analysis family guide

References (sample data, literature)

• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).

• Operator provenance and references — the sources of the research/methods this op family came from.

• The canonical algorithm (author, year) and its uses are named in the family usage guide above.

Runnable examples (verified samples that actually call this op)

• (none yet)

Ops the type connects to (they accept measurement as input)

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Same category (geodesy)

dem_geodetic_to_ecef · dem_ecef_to_geodetic · dem_geocentric_grid · dem_cell_size_webmercator · dem_geodetic_slope

*Provenance: demops.py — DEM operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.