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samstars.features.cost_surface

samstars.features.cost_surface

CostSurfaceWeights dataclass

Source code in samstars/features/cost_surface.py 
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@dataclass
class CostSurfaceWeights:
    grad: float = 0.4
    gap: float = 0.3
    tex: float = 0.3
    slic: float = 0

    def __post_init__(self):
        """Validate and normalize configuration after initialization."""
        s = self.grad + self.gap + self.tex + self.slic
        if abs(s - 1) > 1e-6:
            raise ValueError("Weights must sum to 1 (got {:.3f})".format(s))

__post_init__()

Validate and normalize configuration after initialization.

Source code in samstars/features/cost_surface.py 
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def __post_init__(self):
    """Validate and normalize configuration after initialization."""
    s = self.grad + self.gap + self.tex + self.slic
    if abs(s - 1) > 1e-6:
        raise ValueError("Weights must sum to 1 (got {:.3f})".format(s))

build_cost_surface(*, wv3_path, chm_path, slic_path=None, weights=(0.4, 0.3, 0.3, 0), nodata_value=-9999.0)

Build cost surface.

Source code in samstars/features/cost_surface.py 
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def build_cost_surface(
    *,
    wv3_path: str | Path,
    chm_path: str | Path,
    slic_path: str | Path | None = None,
    weights: tuple[float, float, float, float] = (0.4, 0.3, 0.3, 0),
    nodata_value: float = -9999.0,
):
    """Build cost surface."""
    w = CostSurfaceWeights(*weights)

    with rasterio.open(wv3_path) as src:
        C, B, G, Y, R, RE, N1, N2 = src.read(masked=True).astype(np.float32)
        profile = src.profile.copy()
        profile["bounds"] = rasterio.transform.array_bounds(
            profile["height"], profile["width"], profile["transform"]
        )

    chm, _ = _read_band(chm_path)

    grad = _chm_gradient(chm)
    gap  = _normalise(1 - _ndvi(R, N1))
    tex  = _texture_entropy(C)

    if slic_path:
        if str(slic_path).lower().endswith(".gpkg"):
            slic_lab = _rasterise_slic_gpkg(slic_path, profile)
        else:                                  # assume raster label image
            slic_lab, _ = _read_band(slic_path)
        edge = _slic_edge(slic_lab)
        w_slic = w.slic
    else:
        edge = 0.0
        s = w.grad + w.gap + w.tex
        w.grad, w.gap, w.tex = (w.grad / s, w.gap / s, w.tex / s)
        w_slic = 0.0
        warnings.warn("No SLIC provided – cost built from 3 terms only.")

    cost = (
        w.grad * grad +
        w.gap  * gap  +
        w.tex  * tex  +
        w_slic * edge
    )
    cost = np.clip(cost, 0, 1).astype(np.float32)

    cost[np.isnan(cost)] = nodata_value
    profile.update(count=1, dtype="float32",
                   compress="deflate",
                   nodata=nodata_value)
    return cost, profile

write_cost_surface(cost, profile, out_path, *, exist_ok=True)

Write cost surface.

Source code in samstars/features/cost_surface.py 
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def write_cost_surface(
    cost: np.ndarray,
    profile: dict,
    out_path: str | Path,
    *,
    exist_ok: bool = True,
):
    """Write cost surface."""
    out_path = Path(out_path)
    if not exist_ok and out_path.exists():
        raise FileExistsError(out_path)
    out_path.parent.mkdir(parents=True, exist_ok=True)
    with rasterio.open(out_path, "w", **profile) as dst:
        dst.write(cost, 1)
    return out_path