Struct ForstnerConfig 

pub struct ForstnerConfig {
    pub radius: i32,
    pub min_trace: f32,
    pub min_det: f32,
    pub max_condition_number: f32,
    pub max_offset: f32,
}

Förstner-style gradient-based refiner.

The Förstner operator fits a subpixel corner location by solving a weighted least-squares system on the image gradient structure tensor within a local window. The thresholds below control when the system is well-conditioned enough to yield a reliable estimate.

Reference: Förstner, W. & Gülch, E. (1987). “A fast operator for detection and precise location of distinct points, corners and centres of circular features.”

Fields

radius: i32

Half-size of the local gradient window (full window is 2*radius+1). A radius of 2 gives a 5×5 patch — large enough to capture the gradient structure around a corner while staying local.

min_trace: f32

Minimum trace of the structure tensor (sum of eigenvalues). Rejects flat regions where gradient energy is too low. The value 25.0 corresponds roughly to an average gradient magnitude of ~5 per pixel in a 5×5 window (5² = 25), filtering out textureless areas.

min_det: f32

Minimum determinant of the structure tensor (product of eigenvalues). Guards against singular or near-singular systems where the least-squares solution is numerically unstable. 1e-3 is a conservative floor that rejects only truly degenerate cases.

max_condition_number: f32

Maximum ratio of the larger to the smaller eigenvalue. A high condition number indicates an edge rather than a corner (one dominant gradient direction). The threshold 50.0 is permissive — standard Harris/Förstner literature suggests values in the 10–100 range depending on noise level and corner sharpness.

max_offset: f32

Maximum displacement (in pixels) from the initial integer seed to the refined subpixel location. Offsets larger than ~1.5 px suggest the seed was mislocated and the refinement is extrapolating rather than interpolating; such results are rejected.

Trait Implementations

impl Clone for ForstnerConfig

fn clone(&self) -> ForstnerConfig

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ForstnerConfig

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ForstnerConfig

fn default() -> Self

Returns the “default value” for a type.

impl Copy for ForstnerConfig