displacement_band_weights — 3D `terrain` op

• Data kinds: mesh → matrix

• Call: import fullseye as fs; fs.ledger.displacement_band_weights(V, F, wavelengths=(0.06, 0.03, 0.015, 0.0075, 0.00375), *, nyquist: 'float' = 2.0, fade: 'float' = 1.0, local_edge=None) -> 'np.ndarray' (to call the implementation directly, import render3d; render3d.displacement_band_weights(V, F, wavelengths=(0.06, 0.03, 0.015, 0.0075, 0.00375), *, nyquist: 'float' = 2.0, fade: 'float' = 1.0, local_edge=None) -> 'np.ndarray'; from the registry, ops3d.get("displacement_band_weights"))

Usage

Per-octave, per-vertex band gate `(K, N)` in [0,1]: 1 where the mesh can carry the

> The detailed description below is the original text — the summary and the headings are translated.

wavelength as geometry, 0 where it would alias.

A vertex with local edge length `e (mean incident edge, :func:mesh_edge_lengths`,

or `local_edge (N,) if given) carries wavelength λ only when λ ≥ nyquist·e`;

the gate rises linearly from 0 at `λ = nyquist·e to 1 at λ = (nyquist+fade)·e`

(`fade=0` → hard cut). Used two ways by the Itokawa pipeline: (i) on the *rendered*

mesh to decide which octaves may be displaced (the rest go to bump normals); (ii) on

the *source* model to measure which wavelengths the real data already carries — the

complement `1 − gate` is the synthetic-relief weight (0 where the data are fine,

1 where they are coarse), so dense regions are not double-textured. Deterministic.

計算は `ratio = λ_k / e_i に対し、fade == 0 なら gate = (ratio ≥ nyquist)` の

二値、それ以外は `gate = clip((ratio − nyquist) / fade, 0, 1)`。返り値は float64

`(K, N)`(K = 波長数、N = 頂点数)。

• `wavelengths: メッシュ単位の波長列(空・非正・非有限は ValueError`)。

`mesh_displace_spectrum` と同じ列を渡す。

• `nyquist`: 「幾何として担える」と見なす波長/辺長比の下限(既定 2 = 1 波長に

2 辺)。0 以下は `ValueError`。

• `fade: 遷移幅(辺長の倍数)。0 で硬い閾値。負は ValueError`。

• `local_edge: 頂点ごとの辺長 (N,) を自分で与える場合(mesh_edge_lengths` の

`per='vertex' 相当)。長さ不一致・非正・非有限は ValueError。None` なら

内部で :func:mesh_edge_lengths を呼ぶ。

`mesh_displace_spectrum` は内部でこの関数を呼ぶので、通常は直接呼ぶ必要はない。直接

使うのは、元データが既に担っている波長を測って `1 − gate を weights` として渡す

(細かい所に合成起伏を二重に載せない)ときと、`bump_normals_fbm` へ回す残りを

決めるとき。

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.

Runnable examples (verified samples that actually call this op)

• itokawa_regolith_hero — py -3.11 examples_3d/itokawa_regolith_hero.py

Ops the type connects to (they accept `matrix` as input)

fuse_to_voxel

Same category (`terrain`)

mesh_displace_fbm · terrain_region_mask · mesh_scatter_boulders · mesh_edge_lengths · mesh_subdivide · mesh_displace_spectrum · bump_normals_fbm

*Provenance: render3d.py — 3D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

displacement_band_weights — 3D terrain op