tb_keypoints_uv_to_points — 2D typed op

• Data kinds: keypoints → points

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

tb_keypoints_uv_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.*

*Knob a does not change the output (measured: identical at 0.1 / 0.5 / 0.9).*

*Knob b does not change the output (measured: identical at 0.1 / 0.5 / 0.9).*

Stages (the ops that come before → this op, left to right):

▸ tb_keypoints_uv_to_points: stages (docs site)

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

▸ tb_keypoints_uv_to_points: other inputs (docs site)

Usage

Image coordinates (N,2) = (u, v) -> point cloud (N,3) = (z, y, x). An exit of keypoints.

The axis convention is written in the op name because in this repo match3d.project_points, which produces keypoints, returns (u, v) = (column, row), while fuse3d.to_points(voxel), which produces points, returns (z, y, x) —— naively connecting them as "the first 2 columns" swaps rows and columns with neither an exception nor a NaN. Here they are swapped explicitly as y = v, x = u before being passed on.

A round trip with points_zyx_to_keypoints_uv is bit-identical (in the direction where z is passed).

Args:

keypoints: (N, 2) of (u, v).

z: z of the plane to place them on (a scalar or an (N,) array).

Returns:

(N, 3) float64 of (z, y, x).

Raises:

ValueError: invalid shape / non-finite / length mismatch of z.

The reprconv op keypoints_uv_to_points bridged into the 2-D evolution registry. The implementation is the same; only the calling convention is adapted to op(v, a, b). This op has no tunable parameters; neither a nor b is used.

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.

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_keypoints 0.50 0.50
tb_keypoints_uv_to_points 0.50 0.50

▸ Load this pipeline  ·  Load & run

Runnable examples (verified samples that actually call this op)

The examples below call the underlying ledger op keypoints_uv_to_points. This bridge op is the same implementation adapted to the fn(v, a, b) convention, so the behaviour carries over unchanged (only the call form differs).

• representation_roundtrip — py -3.11 examples/representation_roundtrip.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 (typed)

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 · tb_voxel_grid_downsample


*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.