The old sar3d core was a port of the superseded Horns_3D notebook and
produced wrong volumes. The compute core now follows the reference
notebook exactly:
- segmented_interleaved frame timing rebuilt from per-trace capture
stamps (uniform tx_per_segment split as the no-stamps fallback), with
the coarse inter-segment dtau and the intra-sweep dtau applied as one
phase ramp before the IFFT;
- ground scene coordinates with the ground_depth_m lift (scene Y=0 is
the ground), full-region grid instead of a window around a center
depth, geo_ref compensation anchored on the ground plane, power 0.3;
- notebook finalization in C++: |acc/cnt|, depth mask, normalization
without the Y-edge planes, separable Gaussian over (Z, X), level;
- CUDA kernel computes geometry in double: float32 loses ~3e-4 of an
A-scan sample in tau and drifts ~1e-4 from the float64 reference.
Live-config keys follow: the center_depth/half_width/grid_n window knobs
are replaced by ground/voxel/y-range/margin/sigma/power/tx_per_segment.
Parity against the notebook npz exports (frames 0034-0036 of the
20260922_mine_fast_true dataset): max|diff| <= 1.6e-6 off the depth-mask
knife edge, identical argmax, level rel diff <= 7e-7. Verified via
make sar3d_parity --dump-dir + scripts/sar3d_volume_compare.py; the
executable spec lives in scripts/sar3d_reference_check.py (bit-tight
against the npz, including the animation shifted-grid arithmetic).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
aweandClaude Fable 5
b8cb572bc4