typed op• 資料種類:counts → feature
• 呼叫:fullseye.apply(img, "tb_dtof_depth", a=0.5, b=0.5)(2-D 的模型是一張圖 + 兩個純量旋鈕 a,b∈[0,1])
*無圖: 該運算子以 counts 為輸入。從影像開始的 Studio 程式無法到達該型別，請參見下方的可執行範例。*
由光子到達時間直方圖得到的距離：`d = c*t/2`。
> 以下的詳細說明為原文 —— 摘要與標題已翻譯。
Direct time-of-flight. The light travels to the target and back, so the
one-way distance is half the round-trip time times the speed of light.
*bin_ps* is the width of one time bin (a 100 ps bin is 1.50 cm of depth).
Four estimators, from crudest to sharpest:
• `"peak"` — the centre of the fullest bin. Quantised to the bin grid;
the error is uniform in `+-half a bin (+-0.75 cm` at 100 ps).
• `"centroid"` — the first moment of the whole histogram. Exact for a
symmetric pulse *with no background*, and badly biased toward the middle
of the window with one — pass `subtract_background=True`.
• `"parabolic"` — a parabola through the peak bin and its two neighbours.
Sub-bin, cheap, and biased for a Gaussian pulse.
• `"gaussian"` — the same parabola fitted to the log of those three
samples, which is the exact vertex for a Gaussian pulse.
Measured on a noiseless simulated return at 2.4371 m (256 bins x 100 ps,
500 ps IRF), absolute error: `peak 1.29 mm, centroid` 4.4e-16 m,
`parabolic 0.067 mm, gaussian` 9.4e-9 m — three orders of magnitude
between the crudest and the sharpest.
With Poisson noise (200 signal + 200 ambient photons, seed 0) the same
four give 13.7 mm, 146.5 mm (with `subtract_background=True`), 8.5 mm and
8.0 mm. Two honest readings of that: once shot noise dominates the sub-bin
estimators buy about 1.6x, not three orders of magnitude, and the centroid
collapses because a median-subtracted ambient floor still leaves noise
across the whole window that drags the first moment toward the centre. Use
`"gaussian" or "parabolic" on noisy data; use "centroid"` only when
the background is genuinely gone.
*offset_ps* is a system delay to remove: ``t_flight = t_measured -
offset_ps``, so a positive offset makes the answer *closer*. Returns the
distance in metres as a float.
Raises `ValueError`: negative, non-finite, non-1-D or all-zero *hist*,
a non-positive *bin_ps*, an unknown *mode*, a non-finite *offset_ps*, a
flat histogram in a peak-based mode (`argmax` would silently pick bin 0
and report the first bin's depth), a peak in the first or last bin with a
sub-bin *mode* (there is no neighbour to fit to — use `"peak"`), a
degenerate three-sample fit, and — instead of returning a negative distance —
an *offset_ps* larger than the measured arrival time.
Typed bridge of the photon op `dtof_depth into the 2-D evolution registry: the same implementation, called under the op(v, a, b) convention. a drives bin_ps (default 100); b` is unused.
• 範例資料目錄(下載 URL / 授權) —— 2-D 用 skimage.data(BSD/公有領域)加合成圖,3-D 給出真實資料源(Stanford/PDS 等)的下載 URL。
• 運算子來歷與參考文獻 —— 該運算子族所依據的研究/方法出處。
• (尚無)
feature 作為輸入)typed)tb_points_to_voxel · tb_estimate_point_normals · tb_iss_keypoints · tb_angle_3points · tb_project_points · tb_render_point_depth · tb_statistical_outlier_removal · tb_radius_outlier_removal
*Provenance: ops.py — 2D 運算子登記表。本條目由 tools/opdocs.py md 自動產生(請勿手動編輯)。*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.