v19.9.0

Highlights

Feature release of NCore 19 with FTheta tangential distortion.

• FTheta tangential distortion coefficients: FThetaCameraModelParameters.tangential_coeffs ([t0, t1], in pixels, default zeros) holds the tangential distortion of FTheta calibrations, which was previously dropped (up to ~12 px in the image corners of wide-angle cameras). Projection evaluates the term as DriveWorks does, and unprojection inverts it with a fixed number of iterations (FThetaCameraModel.tangential_iterations, worst round trip error ~5e-4 px on a 120 deg FOV camera with strong tangential distortion).
  • Models without tangential coefficients produce bit-identical results.
  • Stored data is unchanged: all-zero coefficients (and an identity linear_cde) are omitted when encoding, and data without the key loads as zeros. Readers older than 19.9 ignore the coefficients and project as if they were zero.
  • Non-zero coefficients require max_angle < pi/2.
• Faster camera models without distortion terms: FTheta skips the linear term when linear_cde is the identity, and OpenCV pinhole skips tangential / thin-prism terms whose coefficients are all zero (outputs are bit-identical). New parameter properties FThetaCameraModelParameters.has_linear_term / has_tangential_distortion, OpenCVPinholeCameraModelParameters.has_tangential_distortion / has_thin_prism_distortion.

Changes since v19.8.6

➕ Added

• (sensors) add FTheta tangential distortion coefficients (b642eef) - @janickm

⚡ Performance

• (sensors) skip zero tangential and thin-prism terms in OpenCV pinhole (c089273) - @janickm
• (sensors) skip identity linear term in FTheta camera model (86be5dd) - @janickm

Full diff: v19.8.6...v19.9.0