img_to_points — 2D bridge op

Data kinds: imagepoints

Call: fullseye.apply(img, "img_to_points", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])

img_to_points: input → output

*The figure is the actual output on a synthetic 128×128 input. Left: input, right: output. Point clouds are drawn as a top-down scatter (brightness = z), 1-D series as a line plot, volumes as the maximum-intensity projection along z, videos as the middle frame, complex images as magnitude; return values that are not pictures are shown as the values themselves.*

Sweeping knob a (0.1 / 0.5 / 0.9, the other knob at its default):

img_to_points: knob a sweep (docs site)

Sweeping knob b (0.1 / 0.5 / 0.9, the other knob at its default):

img_to_points: knob b sweep (docs site)

On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):

img_to_points: other inputs (docs site)

*The 4th column is a colour (H,W,3) input. This op handles colour without crossing channels (it does not convolve the colour channel as a third spatial axis).*

Usage

Read the image as a height field and turn it into an (x, y, z) point cloud (N,3).

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

各画素 `(row, col) を 1 点 (x, y, z) = (col * 10/W, row * 10/H, value * 10 * s)`

に写す —— 画像の幅・高さを 一辺 10 の箱 に正規化した座標(`POINTS_BOX`)。

点群 op の橋渡し(`tb_*`)が束縛している半径・境界箱・格子解像度はこの尺度

(連鎖ファザーの種 `[0,10)^3`)を前提にしているので、画素座標のまま渡すと

半径系 op の近傍が空になり占有格子が全 0 になる(実測)。画素に戻すなら

`x * W / 10y * H / 10。列の規約は camera.depth_to_points` と同じ

(x, y, z) —— `reprconv(z, y, x)` とは逆なので、その族へ渡すときは

`tb_points_zyx_to_keypoints_uv` 等の入口で読み替えること。

• `a → 高さの倍率 s = 0.25 + 1.75 * a`(a=0.5 で 1.125。値域 [0,1] の画像なら

z の範囲は x, y と同じ桁 [0, 11.25] になり、点群 op が「平面」でなく「地形」を見る)。

• `b → 間引きの歩幅 stride = 1 + int(b * 3)`(b=0.5 で 2。128×128 なら

4,096 点。b=0 で全画素、b=1 で 1/16)。

• 返り値: `(N, 3) float64、N = ceil(H/stride) * ceil(W/stride)`。空にはならない。

• 順序は行優先(row-major)で決定的。同じ入力なら同じ配列。

使いどころ: 点群 op(`tb_alpha_shape_boundary / tb_estimate_point_normals` /

`tb_points_to_voxel` …)を 1 枚の画像から 試す入口。DEM(標高図)を

`value = 標高 / 最大標高` に正規化して渡せば、そのまま地形の点群になる。

Detailed usage guide

gallery2d_bridge 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.

Try it in Studio

The program below has been verified to run (same input as the figure). In Studio's help this block becomes buttons that load and run it on the spot.

img_to_points 0.50 0.50

▸ Load this pipeline  ·  Load & run

Runnable examples (verified samples that actually call this op)

gallery2d_bridgepy -3.11 examples/gallery2d_bridge.py

Ops the type connects to (they accept points as input)

identity · tb_points_to_voxel · tb_estimate_point_normals · tb_iss_keypoints · tb_project_points · tb_render_point_depth · tb_statistical_outlier_removal · tb_radius_outlier_removal

Same category (bridge)

img_to_keypoints · img_to_signal · img_to_projection_profile · img_to_counts · img_to_matrix · img_to_video · img_to_volume · img_to_lightfield


*Provenance: ops.py — 2D 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.