fix: PhysicalFeatureExtractor 除零 → 设零而非人为放大

- 之前 np.sign(x)*1e-12 在 x=0 时得 0，a/0=inf
- 固定 1e-12 兜底又会制造极端比值(14080/1e-12=1.4e16)
- 改为: 分母<1e-10 时直接设 ratio=0，不做人为放大
- 物理意义: 波段为零的像素，光谱比值无意义

src/preprocessing/spectral_Preprocessing.py

@@ -502,11 +502,15 @@ class PhysicalFeatureExtractor(TransformerMixin, BaseEstimator, _ArrayAsFloat64)
             a = X[:, ia]; b = X[:, ib]
             if ftype == 'ratio':
                 denom = a + b
-                denom = np.where(np.abs(denom) < 1e-12, 1e-12, denom)
-                feats.append(((a - b) / denom).reshape(-1, 1))
+                valid = np.abs(denom) >= 1e-10
+                vals = np.zeros_like(a, dtype=np.float64)
+                vals[valid] = (a[valid] - b[valid]) / denom[valid]
+                feats.append(vals.reshape(-1, 1))
             else:  # ratio_single
-                denom = np.where(np.abs(b) < 1e-12, 1e-12, b)
-                feats.append((a / denom).reshape(-1, 1))
+                valid = np.abs(b) >= 1e-10
+                vals = np.zeros_like(a, dtype=np.float64)
+                vals[valid] = a[valid] / b[valid]
+                feats.append(vals.reshape(-1, 1))
         out = np.hstack(feats)
         out = np.nan_to_num(out, nan=0.0, posinf=0.0, neginf=0.0)
         out = np.clip(out, -1e15, 1e15)