dem_flow_direction — DEM hydrology op

• Data kinds: depth → labels

• Call: import demops; demops.dem_flow_direction(dem, cell_size, nodata='error') (or opsdem.get("dem_flow_direction"))

Usage

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

D8 流向。O'Callaghan & Mark (1984)。

返り値は `(H, W) の整数で、0-7 が :data:_D8 の並び、-1` が

「流出先なし」(周囲より低い = 窪地、または境界外へ出る)。

`nodata="outlet"` なら、欠測セルへ向かう流れを許す(そこで系を出る)。

`"barrier" なら欠測へは流れない。欠測セル自身は常に -1`。

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 labels as input)

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Same category (hydrology)

dem_fill_sinks · dem_flow_accumulation · dem_stream_network

*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.