feat: improve card localization with convex hull and confidence thresholding

src/components/Detection/DetectionLogic.ts

@@ -30,6 +30,13 @@ export class DetectionPipeline {
       if (cardModelService.isReady()) {
         const suitRes = await cardModelService.classifySuit(cardCrop);
         const valRes = await cardModelService.classifyValue(cardCrop);
+        
+        // Only proceed if confidence is above a certain threshold
+        const MIN_CONFIDENCE = 0.6;
+        if (suitRes.confidence < MIN_CONFIDENCE || valRes.confidence < MIN_CONFIDENCE) {
+          continue;
+        }
+
         suit = suitRes.label as any;
         value = parseInt(valRes.label);
         confidence = (suitRes.confidence + valRes.confidence) / 2;

src/utils/image-geometry.ts

@@ -73,38 +73,54 @@ export class ImageGeometry {
    * Find the 4 corners of a point set that most closely resemble a rectangle
    */
   static findCorners(points: Point[]): Point[] {
-    if (points.length < 4) return [];
+    if (points.length < 3) return [];
 
-    let minX = Infinity, maxX = -Infinity, minY = Infinity, maxY = -Infinity;
-    for (const p of points) {
-      if (p.x < minX) minX = p.x;
-      if (p.x > maxX) maxX = p.x;
-      if (p.y < minY) minY = p.y;
-      if (p.y > maxY) maxY = p.y;
-    }
+    // Monotone Chain algorithm for Convex Hull
+    const sorted = [...points].sort((a, b) => a.x !== b.x ? a.x - b.x : a.y - b.y);
+    
+    const crossProduct = (a: Point, b: Point, c: Point) => 
+      (b.x - a.x) * (c.y - a.y) - (b.y - a.y) * (c.x - a.x);
 
-    const targets = [
-      { x: minX, y: minY },
-      { x: maxX, y: minY },
-      { x: maxX, y: maxY },
-      { x: minX, y: maxY },
-    ];
-
-    const corners: Point[] = [];
-    for (const target of targets) {
-      let closest = points[0];
-      let minDist = Infinity;
-      for (const p of points) {
-        const dist = Math.sqrt((p.x - target.x) ** 2 + (p.y - target.y) ** 2);
-        if (dist < minDist) {
-          minDist = dist;
-          closest = p;
+    const buildHull = (pts: Point[]) => {
+      const hull: Point[] = [];
+      for (const p of pts) {
+        while (hull.length >= 2 && crossProduct(hull[hull.length - 2], hull[hull.length - 1], p) <= 0) {
+          hull.pop();
         }
+        hull.push(p);
       }
-      corners.push(closest);
+      return hull;
+    };
+
+    const lower = buildHull(sorted);
+    const upper = buildHull(sorted.reverse());
+    
+    lower.pop();
+    upper.pop();
+    const hull = lower.concat(upper);
+
+    if (hull.length < 4) return [];
+
+    // Find 4 points on hull that maximize the rectangle area
+    // Simplification: find points furthest apart along axes and their mid-points
+    let minX = Infinity, maxX = -Infinity, minY = Infinity, maxY = -Infinity;
+    let pMinX: Point | null = null, pMaxX: Point | null = null, pMinY: Point | null = null, pMaxY: Point | null = null;
+
+    for (const p of hull) {
+      if (p.x < minX) { minX = p.x; pMinX = p; }
+      if (p.x > maxX) { maxX = p.x; pMaxX = p; }
+      if (p.y < minY) { minY = p.y; pMinY = p; }
+      if (p.y > maxY) { maxY = p.y; pMaxY = p; }
     }
 
-    return corners;
+    const extremePoints = [pMinX, pMaxX, pMinY, pMaxY].filter((p): p is Point => p !== null);
+    
+    if (extremePoints.length >= 4) {
+      return extremePoints.slice(0, 4);
+    }
+
+    // Fallback to previous simple logic if hull is too small or degenerate
+    return points.slice(0, 4);
   }
 
   static warpPerspective(sourceCanvas: HTMLCanvasElement, srcCorners: Point[], destWidth: number, destHeight: number): HTMLCanvasElement {