Switched to 7-point algorithm.

Exclude points matches with low stdev.

Cargo.toml

@@ -20,6 +20,7 @@ spade = { version = "2.2", default_features = false }
 wgpu = { version = "0.16", default-features = false, features = ["wgsl"] }
 pollster = { version = "0.3", default-features = false }
 bytemuck = { version = "*", features = ["derive"] }
+roots = { version = "0.0.8", default-features = false }
 
 [profile.release]
 strip = true

src/correlation.rs

@@ -4,10 +4,12 @@ use std::sync::atomic::{AtomicUsize, Ordering};
 
 type Point = (usize, usize);
 
+// TODO 0.17 Improve performance with feature-rich images.
 const THRESHOLD: f32 = 0.80;
-const KERNEL_SIZE: usize = 7;
+const KERNEL_SIZE: usize = 15;
 const KERNEL_WIDTH: usize = KERNEL_SIZE * 2 + 1;
 const KERNEL_POINT_COUNT: usize = KERNEL_WIDTH * KERNEL_WIDTH;
+const MIN_STDEV: f32 = 3.0;
 
 #[derive(Debug)]
 pub struct PointData<const KPC: usize> {
@@ -64,6 +66,9 @@ impl KeypointMatching {
                     Some(it) => it,
                     None => return vec![],
                 };
+                if data1.stdev < MIN_STDEV {
+                    return vec![];
+                }
                 let points2 = points2;
                 points2
                     .iter()
@@ -73,6 +78,9 @@ impl KeypointMatching {
                             Some(it) => it,
                             None => return None,
                         };
+                        if data2.stdev < MIN_STDEV {
+                            return None;
+                        }
                         correlate_points(data1, data2)
                             .filter(|corr| *corr > THRESHOLD)
                             .map(|_| (*p1, *p2))

src/crosscorrelation.rs

@@ -4,7 +4,7 @@ use rayon::prelude::*;
 use std::{cell::RefCell, error, ops::Range, sync::atomic::AtomicUsize, sync::atomic::Ordering};
 
 const SCALE_MIN_SIZE: usize = 64;
-const KERNEL_SIZE: usize = 7;
+const KERNEL_SIZE: usize = 5;
 const KERNEL_WIDTH: usize = KERNEL_SIZE * 2 + 1;
 const KERNEL_POINT_COUNT: usize = KERNEL_WIDTH * KERNEL_WIDTH;
 

src/fast.rs

@@ -26,7 +26,7 @@ const FAST_CIRCLE_PIXELS: [(i8, i8); 16] = [
 const KERNEL_SIZE: usize = 3;
 // TODO: update to match results from previous C version
 const FAST_THRESHOLD: u8 = 15;
-const KEYPOINT_SCALE_MIN_SIZE: usize = 256;
+const KEYPOINT_SCALE_MIN_SIZE: usize = 512;
 const FAST_NUM_POINTS: usize = 12;
 const FAST_CIRCLE_LENGTH: usize = FAST_CIRCLE_PIXELS.len() + FAST_NUM_POINTS - 1;