Raster cache

Remote terminal refinement reads raster windows. Pourpoint requests the TIFF metadata entries and compressed byte ranges required for the selected window instead of downloading the complete raster. Materialized windows can be cached on disk for reuse across overlapping watersheds.

This bounded-read design does not mean every file is always read partially. A cold engine open may fetch the small manifest and graph completely. Required Parquet ranges may also be retained in an in-memory per-engine cache. Set HFX_CACHE_DIR to choose the persistent metadata and raster-window cache location; otherwise the operating-system cache directory is used.

Refinement behavior

refine=True is best effort. If no usable D8 declaration exists, delineation can return whole source units. refine=False disables terminal refinement:

import pourpoint

engine = pourpoint.Engine("/data/hfx/local", refine=False)

The project-hosted GRIT manifest declares one compatible D8 pair at aux/d8/flow_dir.tif and aux/d8/flow_acc.tif. The engine returns a terminal sub-polygon at the selected raster seed when refinement succeeds. In the current development version, refinement ranks threshold-qualified cells throughout the terminal unit against the vector snap point, or the request point for containment. No raster search radius is imposed. Reads remain terminal-localized.

For the complete released CRS, unit, data type, predictor, and COG boundary, see D8 compatibility and remote layout.