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tono/docs/nodes/Watershed Segmentation.md

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Watershed Segmentation

Segment a height field into grains using the two-stage Gwyddion watershed workflow: drop-based seed location followed by watershed growth. Supports hill or valley detection and optional union/intersection with an existing mask.

Inputs

Name Type Required Description
field DATA_FIELD Yes Input topographic field
mask IMAGE No Optional existing mask to combine with the watershed result

Outputs

Name Type Description
mask IMAGE Binary grain mask from watershed segmentation

Controls

Name Type Default Description
invert_height BOOLEAN False When True, detects valleys instead of hills (inverts the height field)
locate_steps INT 10 Number of drop steps in the seed location stage (1-200)
locate_threshold INT 10 Minimum drop threshold for seed acceptance (0-100000)
locate_drop_size FLOAT 0.1 Relative drop size for seed location stage (0.0001-1.0)
watershed_steps INT 20 Number of steps in the watershed growth stage (1-2000)
watershed_drop_size FLOAT 0.1 Relative drop size for watershed growth stage (0.0001-1.0)
combine_mode dropdown replace How to combine with an existing mask: replace (ignore existing), union (OR), or intersection (AND)

Notes

  • Parameter tuning is required; the default settings work best for isolated round features.
  • Very large locate_threshold values may reject all seeds and produce an empty mask.