dem_cell_size_webmercator — DEM geodesy op

Data kinds: nonemeasurement (an op determined by its arguments alone — it takes no image or data input)

Call: import demops; demops.dem_cell_size_webmercator(zoom, lat_deg) (or opsdem.get("dem_cell_size_webmercator"))

Usage

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

Web メルカトルのタイルの地上分解能 [m/px]。緯度で変わる

`156543.03392804097 * cos(lat) / 2^zoom`(タイルが 256 px の場合)。

実測の目安: 東京(北緯 35.68 度)の z=15 で 3.880 m、赤道では 4.777 m。

赤道の値をそのまま使うと東京で傾斜が 23 % 過小になります —— これは

例外を出さずに全部の下流の数字を狂わせるので、この族で最も多い事故です。

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)

Same category (geodesy)

dem_geodetic_to_ecef · dem_ecef_to_geodetic · dem_geocentric_grid · dem_earth_curvature_drop · 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.