nx_motion.nx

buildroot/runtime/nx_motion.nx

6488 B197 linesdepth 5pulls 6 transitivereach 1 importersview sourcekind librarytopic motion

docs dependencies structs consts functions

about

nx_motion.nx -- frame-to-frame motion (Lucas-Kanade optical flow). Brightness-constancy + small-motion assumption: I(x, y, t) = I(x + u, y + v, t + 1) Taylor expand: I_x * u + I_y * v + I_t = 0 Over an N-pixel window this is N equations in 2 unknowns; solve via 2x2 least-squares (normal equations + Cramer's rule). What this unlocks: + motion detection (frame diff) + tracking (per-pixel flow vectors) + camera-motion estimation (mean flow direction) + scene-cut detection (flow magnitude spike) + activity recognition substrate Returns flow in Q8 sub-pixel precision (1 unit = 1/256 pixel). 5x5 integration window default. genealogy_id: lucas_kanade_1981 + horn_schunck_1981 lineage_id: gradient_based_optical_flow + 2x2_least_squares

dependencies 2 imports · 1 importers

imports: syscalls.nxnx_image.nx

imported by: nx_motion_test.nx

structs

90	struct FlowField

consts

32	const NX_MOTION_Q: i64 = 256 // Q8 sub-pixel
33	const NX_MOTION_WIN: i64 = 5 // 5x5 integration

functions

39	func nx_motion_frame_diff(a: Image, b: Image) -> *Image called by 1: main calls 3: nx_image_alloc nx_image_get nx_image_set
64	func nx_motion_temporal_grad(frame1: Image, frame2: Image) -> *ImageS64 called by 2: nx_motion_lucas_kanade main calls 3: nx_image_s64_alloc nx_image_get nx_image_s64_set
95	func nx_motion_lucas_kanade(frame1: Image, frame2: Image) -> *FlowField called by 1: main calls 6: nx_image_sobel_x nx_image_sobel_y nx_motion_temporal_grad nx_image_s64_alloc nx_image_s64_get nx_image_s64_set
163	func nx_motion_mean_flow(flow: *FlowField, mag_threshold: i64, called by 1: main calls 1: nx_image_s64_get