Fix complex-roof segmentation: recover small planes, reject walls, handle solar

Cluster of fixes triggered by 8121 Golden Vista Way failing hard (4 planes on
what's really an 8+ plane multi-wing roof with existing solar).

- fusion.min_fraction 0.05 -> 0.02
5% of building area was eating legitimate hip caps and wing sections on
complex roofs. 2% keeps them.

- radio_backbone: add solar panel prompts, count them as roof
ROOF_PROMPTS gains "solar panel array on roof" and "photovoltaic panels
installed on roof". Existing solar was being pushed toward "wall"/"shadow"
by RADIO, causing fusion to carve holes in the roof mask (41% roof
classification on parents' house vs 73% on a bare-roof reference).

- ransac_planes: reject planes with pitch > 65deg
RANSAC was fitting the occasional facade edge in the DSM as a "plane"
at 70-80deg pitch. Consume the inliers so we don't refit, but don't emit.

- geo_export: polygon simplification epsilon 0.025 -> 0.010
Hip caps and dormers were being collapsed into straight lines at 2.5% of
perimeter. Tighter tolerance preserves architectural detail.

- radio_backbone.get_roof_mask defaults to len(ROOF_PROMPTS)
so future prompt additions don't require touching call sites.

Result on 8121 Golden Vista: RANSAC 7 -> final 10 planes exported.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

fusion.py

@@ -14,7 +14,7 @@ def fuse_segmentations(
     ransac_labels: np.ndarray,
     radio_scores: np.ndarray,
     building_mask: np.ndarray,
-    num_roof_classes: int = 4,
+    num_roof_classes: int = 6,
 ) -> np.ndarray:
     """Merge RANSAC plane labels with RADIO appearance scores.
 
@@ -110,11 +110,15 @@ def split_disconnected_regions(label_map: np.ndarray) -> np.ndarray:
 def merge_small_fragments(
     label_map: np.ndarray,
     building_mask: np.ndarray,
-    min_fraction: float = 0.05,
+    min_fraction: float = 0.02,
 ) -> np.ndarray:
     """Merge fragments smaller than min_fraction of building area.
 
     Small fragments get absorbed into their nearest neighboring plane.
+
+    Default 0.02 (2%) preserves real hip caps and small wings on complex roofs.
+    Higher values (0.05) merged legitimate small planes into their neighbors —
+    see 8121 Golden Vista Way for a failure case at 0.05.
     """
     building_area = (building_mask > 0).sum()
     min_pixels = int(building_area * min_fraction)

geo_export.py

@@ -101,9 +101,11 @@ def labels_to_geojson(
             if area_sqft < min_area_sqft:
                 continue
 
-            # Simplify polygon (2.5% of perimeter — clean roof plane shapes)
+            # Simplify polygon. Lower epsilon (1% vs previous 2.5%) preserves
+            # real geometry on complex roofs — hip caps and dormers were being
+            # collapsed into straight lines at 2.5%.
             perimeter = cv2.arcLength(contour, True)
-            epsilon = 0.025 * perimeter
+            epsilon = 0.010 * perimeter
             simplified = cv2.approxPolyDP(contour, epsilon, True)
 
             coords = [pixel_to_geo(pt[0][0], pt[0][1], w, h, bounds) for pt in simplified]

pipeline.py

@@ -158,7 +158,7 @@ def run(
     result.status.append("Fusing geometry + appearance...")
     fused = fuse_segmentations(ransac_labels, score_map, cropped_mask)
     fused = split_disconnected_regions(fused)
-    fused = merge_small_fragments(fused, cropped_mask, min_fraction=0.05)
+    fused = merge_small_fragments(fused, cropped_mask, min_fraction=0.02)
     result.fused_labels = fused
 
     n_final = len(set(np.unique(fused)) - {0})

radio_backbone.py

@@ -18,12 +18,17 @@ from einops import rearrange
 
 PATCH_SIZE = 16
 
-# Zero-shot text prompts for roof segmentation
+# Zero-shot text prompts for roof segmentation.
+# Solar-array prompts count as "roof" — the pixels underneath still belong
+# to a roof plane; without these prompts, RADIO pushes solar-covered
+# pixels toward "wall"/"shadow" and fusion carves holes in the roof mask.
 ROOF_PROMPTS = [
     "flat roof plane",
     "pitched roof plane",
     "hip roof plane",
     "gable roof plane",
+    "solar panel array on roof",
+    "photovoltaic panels installed on roof",
 ]
 NON_ROOF_PROMPTS = [
     "sky",
@@ -259,9 +264,12 @@ def zero_shot_segment(
     return score_map_np, seg_map, all_labels
 
 
-def get_roof_mask(seg_map: np.ndarray, num_roof_classes: int = 4) -> np.ndarray:
+def get_roof_mask(seg_map: np.ndarray, num_roof_classes: int = None) -> np.ndarray:
     """Extract binary roof mask from segmentation map.
 
     Assumes first num_roof_classes indices in the label list are roof types.
+    Defaults to len(ROOF_PROMPTS) so this stays correct if the prompt list changes.
     """
+    if num_roof_classes is None:
+        num_roof_classes = len(ROOF_PROMPTS)
     return (seg_map < num_roof_classes).astype(np.uint8)

ransac_planes.py

@@ -154,8 +154,15 @@ def fit_planes(
         pitch_deg = float(np.degrees(np.arccos(np.clip(abs(refined_normal[2]), 0, 1))))
         azimuth_deg = float(np.degrees(np.arctan2(-refined_normal[0], -refined_normal[1])) % 360)
 
+        # Reject wall-like fits — roofs top out around 60° pitch (12/12 = 45°).
+        # Anything steeper is almost certainly RANSAC finding a facade edge in the DSM.
+        if pitch_deg > 65.0:
+            # Still consume the inliers so we don't re-fit the same wall,
+            # but don't emit this plane.
+            continue
+
         planes.append({
-            "segment_id": plane_idx + 1,
+            "segment_id": len(planes) + 1,
             "equation": [float(refined_normal[0]), float(refined_normal[1]),
                          float(refined_normal[2]), float(refined_d)],
             "normal": refined_normal.tolist(),