dc-l1-tokyo-ring-orientation

Rerun

import geopandas as gpd

def inspect_geojson(file_path):
    try:
        gdf = gpd.read_file(file_path)
        print(f"Total features: {len(gdf)}")
        print(f"Geometry types: {gdf.geometry.type.unique()}")
        print(f"First 5 geometries:\n{gdf.geometry.head()}")
        
        # Check for invalid geometries
        invalid_count = gdf.geometry.is_valid.value_counts().get(False, 0)
        print(f"Invalid geometries count: {invalid_count}")
        
        if invalid_count > 0:
            print("Sample invalid geometry:")
            print(gdf[~gdf.geometry.is_valid].geometry.head())
            
    except Exception as e:
        print(f"Error: {e}")

inspect_geojson('tokyo_buildings_legacy.geojson')

import geopandas as gpd
import json

def check_winding_order(gdf):
    """
    GeoJSON spec (RFC 7946) requires exterior rings to be counter-clockwise (CCW)
    and interior rings (holes) to be clockwise (CW). 
    However, some tools use the opposite convention.
    The issue described (interiors shaded incorrectly) often implies 
    inverted winding orders or incorrect orientation of rings.
    """
    print("Checking ring orientations...")
    # We will check the first feature's rings
    first_geom = gdf.geometry.iloc[0]
    if hasattr(first_geom, 'interiors'):
        print(f"First geometry has {len(first_geom.interiors)} interior rings.")
        
def fix_geometries(input_path, output_path):
    gdf = gpd.read_file(input_path)
    
    print(f"Original invalid geometries: {sum(~gdf.geometry.is_valid)}")
    
    # The issue "interiors shaded incorrectly: holes appear filled and exteriors render as empty space"
    # sounds like the polygon winding order is completely reversed (exterior is CW, interior is CCW)
    # or the orientation of the rings is simply wrong for standard GeoJSON rendering.
    
    # In Shapely/GeoPandas, 'orient' can fix this.
    # According to RFC 7946:
    # Exterior ring should be Counter-Clockwise (CCW).
    # Interior rings should be Clockwise (CW).
    
    from shapely.geometry import Polygon, MultiPolygon
    from shapely.ops import orient

    def fix_polygon(geom):
        if geom.is_empty:
            return geom
        if isinstance(geom, Polygon):
            # orient(polygon, sign=1.0) makes exterior CCW and interior CW
            return orient(geom, sign=1.0)
        elif isinstance(geom, MultiPolygon):
            return MultiPolygon([orient(p, sign=1.0) for p in geom.geoms])
        return geom

    gdf['geometry'] = gdf['geometry'].apply(fix_polygon)
    
    # After orienting, let's ensure they are valid (though orient usually handles it)
    # We use buffer(0) as a common trick to fix minor topological issues
    gdf['geometry'] = gdf['geometry'].buffer(0)
    
    print(f"New invalid geometries: {sum(~gdf.geometry.is_valid)}")
    
    gdf.to_file(output_path, driver='GeoJSON')
    print(f"Saved to {output_path}")

if __name__ == "__main__":
    fix_geometries('tokyo_buildings_legacy.geojson', 'tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon
from shapely.ops import orient

def test_orientation(file_path):
    gdf = gpd.read_file(file_path)
    geom = gdf.geometry.iloc[0]
    print(f"Geometry: {geom.geom_type}")
    
    # For a Polygon, geom.exterior.is_ccw tells us if exterior is CCW
    # For a Polygon, geom.interiors[0].is_ccw tells us if the first interior is CCW
    
    if isinstance(geom, Polygon):
        print(f"Exterior CCW: {geom.exterior.is_ccw}")
        for i, interior in enumerate(geom.interiors):
            print(f"Interior {i} CCW: {interior.is_ccw}")
    elif isinstance(geom, MultiPolygon):
        print("MultiPolygon detected, checking first part...")
        sub_geom = geom.geoms[0]
        print(f"Exterior CCW: {sub_geom.exterior.is_ccw}")
        for i, interior in enumerate(sub_geom.interiors):
            print(f"Interior {i} CCW: {interior.is_ccw}")

print("--- Legacy Data ---")
test_orientation('tokyo_buildings_legacy.geojson')
print("\n--- Fixed Data ---")
test_orientation('tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon
from shapely.ops import orient

def test_orientation(file_path):
    gdf = gpd.read_file(file_path)
    # We need to check ALL features to be sure, but let's start with the first one.
    # If the first one is False, maybe it's because of how Shapely represents it?
    # Let's use the actual coordinate values to verify.
    
    geom = gdf.geometry.iloc[0]
    print(f"Geometry: {geom.geom_type}")
    
    # Manual check of exterior
    coords = list(geom.exterior.coords)
    print(f"Exterior coords: {coords[:3]} ...")
    
    # Calculate signed area to determine winding order
    # Area > 0 means CCW in some conventions, but let's use a standard method
    def is_ccw(coords):
        area = 0
        for i in range(len(coords) - 1):
            x1, y1 = coords[i]
            x2, y2 = coords[i+1]
            area += (x2 - x1) * (y2 + y1)
        return area < 0

    print(f"Is exterior CCW (manual): {is_ccw(coords)}")

if __name__ == "__main__":
    print("--- Legacy Data ---")
    test_orientation('tokyo_buildings_legacy.geojson')
    print("\n--- Fixed Data ---")
    test_orientation('tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon
from shapely.ops import orient

def fix_geometries(input_path, output_path):
    gdf = gpd.read_file(input_path)
    
    def fix_polygon(geom):
        if geom.is_empty:
            return geom
        if isinstance(geom, Polygon):
            # The issue is that the exterior is CW and interiors are CCW.
            # orient(geom, sign=1.0) makes exterior CCW and interior CW.
            # However, orient() only works if the geometry is 'correctly' oriented
            # in its current state or if we define the expected sign.
            # Actually, orient(geom, sign=1.0) forces exterior to be CCW.
            # Let's check if it actually changes the coordinates.
            return orient(geom, sign=1.0)
        elif isinstance(geom, MultiPolygon):
            return MultiPolygon([orient(p, sign=1.0) for p in geom.geoms])
        return geom

    # Let's test the effect of orient(geom, sign=1.0) on a single polygon
    test_poly = gdf.geometry.iloc[0]
    fixed_poly = orient(test_poly, sign=1.0)
    
    print(f"Original exterior coords: {list(test_poly.exterior.coords)[:3]}")
    print(f"Fixed exterior coords:    {list(fixed_poly.exterior.coords)[:3]}")
    
    # If they are the same, it means the sign=1.0 didn't flip it.
    # This might happen if Shapely thinks it's already CCW.
    # But my manual check said False (CW).
    
    gdf['geometry'] = gdf['geometry'].apply(fix_polygon)
    gdf.to_file(output_path, driver='GeoJSON')

if __name__ == "__main__":
    fix_geometries('tokyo_buildings_legacy.geojson', 'tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon
from shapely.ops import orient

def fix_geometries(input_path, output_path):
    gdf = gpd.read_file(input_path)
    
    def fix_polygon(geom):
        if geom.is_empty:
            return geom
        if isinstance(geom, Polygon):
            # sign=1.0: exterior CCW, interior CW
            # sign=-1.0: exterior CW, interior CCW
            # RFC 7946 requires CCW exterior and CW interior.
            return orient(geom, sign=1.0)
        elif isinstance(geom, MultiPolygon):
            return MultiPolygon([orient(p, sign=1.0) for p in geom.geoms])
        return geom

    gdf['geometry'] = gdf['geometry'].apply(fix_polygon)
    
    # Also fix validity issues which might cause import rejections
    gdf['geometry'] = gdf['geometry'].buffer(0)
    
    gdf.to_file(output_path, driver='GeoJSON')

if __name__ == "__main__":
    fix_geometries('tokyo_buildings_legacy.geojson', 'tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon
from shapely.ops import orient

def fix_geometries(input_path, output_path):
    gdf = gpd.read_file(input_path)
    
    def fix_polygon(geom):
        if geom.is_empty:
            return geom
        if isinstance(geom, Polygon):
            # RFC 7946 requires:
            # Exterior ring: Counter-Clockwise (CCW)
            # Interior rings: Clockwise (CW)
            # orient(geom, sign=1.0) does exactly this.
            return orient(geom, sign=1.0)
        elif isinstance(geom, MultiPolygon):
            return MultiPolygon([orient(p, sign=1.0) for p in geom.geoms])
        return geom

    # Apply fix
    gdf['geometry'] = gdf['geometry'].apply(fix_polygon)
    
    # Ensure validity to satisfy tile-server requirements
    # buffer(0) is a standard way to fix self-intersections or other topology issues
    gdf['geometry'] = gdf['geometry'].buffer(0)
    
    # Save the fixed file
    gdf.to_file(output_path, driver='GeoJSON')
    print(f"Successfully fixed {len(gdf)} features and saved to {output_path}")

if __name__ == "__main__":
    fix_geometries('tokyo_buildings_legacy.geojson', 'tokyo_buildings_fixed.geojson')

import geopandas as gpd

def check_rings(file_path):
    gdf = gpd.read_file(file_path)
    for i, geom in enumerate(gdf.geometry):
        if isinstance(geom, Polygon):
            # Exterior
            ext = list(geom.exterior.coords)
            # Check if CCW using shoelace formula on exterior
            area = 0
            for j in range(len(ext)-1):
                area += (ext[j+1][0] - ext[j][0]) * (ext[j+1][1] + ext[j][1])
            ext_ccw = area < 0
            
            # Interiors
            for k, interior in enumerate(geom.interiors):
                int_coords = list(interior.coords)
                i_area = 0
                for j in range(len(int_coords)-1):
                    i_area += (int_coords[j+1][0] - int_coords[j][0]) * (int_coords[j+1][1] + int_coords[j][1])
                int_ccw = i_area < 0
                
                if not ext_ccw:
                    print(f"Feature {i} exterior is NOT CCW")
                if int_ccw:
                    print(f"Feature {i} interior {k} is NOT CW")
            
            if not ext_ccw:
                 print(f"Feature {i} exterior is NOT CCW")
        elif i == 0:
             print("First feature is not a Polygon")

check_rings('tokyo_buildings_fixed.geojson')

from shapely.geometry import Polygon

def check_rings(file_path):
    import geopandas as gpd
    gdf = gpd.read_file(file_path)
    errors = 0
    for i, geom in enumerate(gdf.geometry):
        if isinstance(geom, Polygon):
            # Exterior
            ext = list(geom.exterior.coords)
            # Check if CCW using shoelace formula on exterior
            area = 0
            for j in range(len(ext)-1):
                area += (ext[j+1][0] - ext[j][0]) * (ext[j+1][1] + ext[j][1])
            ext_ccw = area < 0
            
            # Interiors
            for k, interior in enumerate(geom.interiors):
                int_coords = list(interior.coords)
                i_area = 0
                for j in range(len(int_coords)-1):
                    i_area += (int_coords[j+1][0] - int_coords[j][0]) * (int_coords[j+1][1] + int_coords[j][1])
                int_cw = i_area > 0
                
                if not int_cw:
                    # print(f"Feature {i} interior {k} is NOT CW")
                    errors += 1
            
            if not ext_ccw:
                # print(f"Feature {i} exterior is NOT CCW")
                errors += 1
        elif i == 0:
             print("First feature is not a Polygon")
    print(f"Total orientation errors found: {errors}")

check_rings('tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon
from shapely.ops import orient

def fix_geometries(input_path, output_path):
    gdf = gpd.read_file(input_path)
    
    def fix_polygon(geom):
        if geom.is_empty:
            return geom
        if isinstance(geom, Polygon):
            # orient(geom, sign=1.0) makes exterior CCW and interior CW
            # If my manual test said it was CW, and orient didn't change it,
            # then sign=1.0 might be the wrong direction for Shapely's internal representation.
            # Let's try both and see which one yields "area < 0" for exterior in my check script.
            # Actually, orient(geom, sign=1.0) is documented to make exterior CCW.
            # Let's just use it.
            return orient(geom, sign=1.0)
        elif isinstance(geom, MultiPolygon):
            return MultiPolygon([orient(p, sign=1.0) for p in geom.geoms])
        return geom

    gdf['geometry'] = gdf['geometry'].apply(fix_polygon)
    gdf['geometry'] = gdf['geometry'].buffer(0)
    gdf.to_file(output_path, driver='GeoJSON')

if __name__ == "__main__":
    fix_geometries('tokyo_buildings_legacy.geojson', 'tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon

def check_rings(file_path):
    gdf = gpd.read_file(file_path)
    errors = 0
    for i, geom in enumerate(gdf.geometry):
        if isinstance(geom, Polygon):
            ext = list(geom.exterior.coords)
            area = 0
            for j in range(len(ext)-1):
                area += (ext[j+1][0] - ext[j][0]) * (ext[j+1][1] + ext[j][1])
            ext_ccw = area < 0
            
            if not ext_ccw:
                errors += 1
                
            for k, interior in enumerate(geom.interiors):
                int_coords = list(interior.coords)
                i_area = 0
                for j in range(len(int_coords)-1):
                    i_area += (int_coords[j+1][0] - int_coords[j][0]) * (int_coords[j+1][1] + int_coords[j][1])
                int_cw = i_area > 0
                if not int_cw:
                    errors += 1
    print(f"Total orientation errors found: {errors}")

check_rings('tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon
from shapely.ops import orient

def fix_geometries(input_path, output_path):
    gdf = gpd.read_file(input_path)
    
    def fix_polygon(geom):
        if geom.is_empty:
            return geom
        if isinstance(geom, Polygon):
            # The issue might be that the input is already "correct" for Shapely
            # but has the wrong orientation for the GeoJSON spec.
            # Let's try sign=-1.0 (Exterior CW, Interior CCW)
            # Wait, if I want Exterior CCW and Interior CW (RFC 7946), 
            # and my manual check said it was NOT CCW (area < 0)...
            # Let's try a different approach. 
            # We will use orient(geom, sign=1.0) and if it doesn't change, 
            # we manually flip the rings.
            
            # But first, let's see what orient(geom, sign=1.0) does to the area.
            # I'll just use orient(geom, sign=1.0) as it is the standard.
            # The fact that it's not working might mean my manual shoelace 
            # logic is flipped or something.
            # Let's check the area in the original.
            return orient(geom, sign=1.0)
        elif isinstance(geom, MultiPolygon):
            return MultiPolygon([orient(p, sign=1.0) for p in geom.geoms])
        return geom

    # Let's try sign=-1.0 if sign=1.0 failed
    # Wait, I just realized: orient(geom, sign=1.0) might not be enough if 
    # the geometry itself is considered 'valid' but with wrong orientation.
    # Let's try to force the orientation.
    
    def force_orientation(geom):
        if isinstance(geom, Polygon):
            # Exterior CCW, Interior CW
            # We'll use the sign that results in positive area for CCW in our shoelace
            # Actually, in my shoelace formula:
            # area = sum (x2 - x1) * (y2 + y1)
            # if area < 0, it's CCW.
            # if area > 0, it's CW.
            
            # Let's try sign=-1.0 for orient
            return orient(geom, sign=-1.0)
        return geom

    # Testing with sign=-1.0
    gdf['geometry'] = gdf['geometry'].apply(force_orientation)
    gdf.to_file(output_path, driver='GeoJSON')

if __name__ == "__main__":
    fix_geometries('tokyo_buildings_legacy.geojson', 'tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon

def check_rings(file_path):
    gdf = gpd.read_file(file_path)
    errors = 0
    for i, geom in enumerate(gdf.geometry):
        if isinstance(geom, Polygon):
            ext = list(geom.exterior.coords)
            area = 0
            for j in range(len(ext)-1):
                area += (ext[j+1][0] - ext[j][0]) * (ext[j+1][1] + ext[j][1])
            ext_ccw = area < 0
            
            if not ext_ccw:
                errors += 1
                
            for k, interior in enumerate(geom.interiors):
                int_coords = list(interior.coords)
                i_area = 0
                for j in range(len(int_coords)-1):
                    i_area += (int_coords[j+1][0] - int_coords[j][0]) * (int_coords[j+1][1] + int_coords[j][1])
                int_cw = i_area > 0
                if not int_cw:
                    errors += 1
    print(f"Total orientation errors found: {errors}")

check_rings('tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon
from shapely.ops import orient

def fix_geometries(input_path, output_path):
    gdf = gpd.read_file(input_path)
    
    def fix_polygon(geom):
        if geom.is_empty:
            return geom
        if isinstance(geom, Polygon):
            # We want: Exterior CCW (area < 0 in shoelace), Interior CW (area > 0 in shoelace)
            # Shapely's orient(geom, sign=1.0) makes exterior CCW.
            # Let's check why my manual shoelace test is failing.
            # If sign=1.0 doesn't work, maybe orient() is not behaving as I expect.
            # Let's manually flip.
            
            # Current orientation
            ext_coords = list(geom.exterior.coords)
            area = 0
            for j in range(len(ext_coords)-1):
                area += (ext_coords[j+1][0] - ext_coords[j][0]) * (ext_coords[j+1][1] + ext_coords[j][1])
            
            # If area > 0, it's CW. We want CCW (area < 0).
            # If area < 0, it's CCW. We want CCW (area < 0).
            # So if area > 0, reverse ext_coords.
            
            new_ext_coords = ext_coords[::-1] if area > 0 else ext_coords
            
            new_interiors = []
            for interior in geom.interiors:
                int_coords = list(interior.coords)
                i_area = 0
                for j in range(len(int_coords)-1):
                    i_area += (int_coords[j+1][0] - int_coords[j][0]) * (int_coords[j+1][1] + int_coords[j][1])
                # We want CW (i_area > 0).
                # If i_area < 0, it's CCW. Reverse it.
                new_int_coords = int_coords[::-1] if i_area < 0 else int_coords
                new_interiors.append(new_int_coords)
                
            return Polygon(new_ext_coords, new_interiors)
            
        elif isinstance(geom, MultiPolygon):
            return MultiPolygon([fix_polygon(p) for p in geom.geoms])
        return geom

    gdf['geometry'] = gdf['geometry'].apply(fix_polygon)
    gdf['geometry'] = gdf['geometry'].buffer(0)
    gdf.to_file(output_path, driver='GeoJSON')

if __name__ == "__main__":
    fix_geometries('tokyo_buildings_legacy.geojson', 'tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon

def check_rings(file_path):
    gdf = gpd.read_file(file_path)
    errors = 0
    for i, geom in enumerate(gdf.geometry):
        if isinstance(geom, Polygon):
            ext = list(geom.exterior.coords)
            area = 0
            for j in range(len(ext)-1):
                area += (ext[j+1][0] - ext[j][0]) * (ext[j+1][1] + ext[j][1])
            
            # In the previous version, I said area < 0 is CCW.
            # Let's re-verify with a simple CCW square: (0,0), (1,0), (1,1), (0,1)
            # x1=0, y1=0; x2=1, y2=0 => (1-0)*(0+0) = 0
            # x2=1, y2=0; x3=1, y3=1 => (1-1)*(1+0) = 0
            # x3=1, y3=1; x4=0, y4=1 => (0-1)*(1+1) = -2
            # x4=0, y4=1; x1=0, y1=0 => (0-0)*(0+1) = 0
            # Total area = -2. So yes, CCW is area < 0.
            
            ext_ccw = area < 0
            if not ext_ccw:
                errors += 1
            
            for k, interior in enumerate(geom.interiors):
                int_coords = list(interior.coords)
                i_area = 0
                for j in range(len(int_coords)-1):
                    i_area += (int_coords[j+1][0] - int_coords[j][0]) * (int_coords[j+1][1] + int_coords[j][1])
                # CW should be area > 0
                int_cw = i_area > 0
                if not int_cw:
                    errors += 1
    print(f"Total orientation errors found: {errors}")

check_rings('tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon

def fix_geometries(input_path, output_path):
    gdf = gpd.read_file(input_path)
    
    def fix_polygon(geom):
        if geom.is_empty:
            return geom
        if isinstance(geom, Polygon):
            # We want: Exterior CCW (area < 0), Interior CW (area > 0)
            
            # Get current exterior
            ext_coords = list(geom.exterior.coords)
            ext_area = 0
            for j in range(len(ext_coords)-1):
                ext_area += (ext_coords[j+1][0] - ext_coords[j][0]) * (ext_coords[j+1][1] + ext_coords[j][1])
            
            # If ext_area > 0, it is CW, so reverse it to make it CCW (ext_area < 0)
            if ext_area > 0:
                ext_coords = ext_coords[::-1]
                
            new_interiors = []
            for interior in geom.interiors:
                int_coords = list(interior.coords)
                int_area = 0
                for j in range(len(int_coords)-1):
                    int_area += (int_coords[j+1][0] - int_coords[j][0]) * (int_coords[j+1][1] + int_coords[j][1])
                
                # If int_area < 0, it is CCW, so reverse it to make it CW (int_area > 0)
                if int_area < 0:
                    int_coords = int_coords[::-1]
                new_interiors.append(int_coords)
                
            return Polygon(ext_coords, new_interiors)
            
        elif isinstance(geom, MultiPolygon):
            return MultiPolygon([fix_polygon(p) for p in geom.geoms])
        return geom

    gdf['geometry'] = gdf['geometry'].apply(fix_polygon)
    # Ensure valid
    gdf['geometry'] = gdf['geometry'].buffer(0)
    gdf.to_file(output_path, driver='GeoJSON')

if __name__ == "__main__":
    fix_geometries('tokyo_buildings_legacy.geojson', 'tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon

def check_rings(file_path):
    gdf = gpd.read_file(file_path)
    errors = 0
    for i, geom in enumerate(gdf.geometry):
        if isinstance(geom, Polygon):
            ext = list(geom.exterior.coords)
            area = 0
            for j in range(len(ext)-1):
                area += (ext[j+1][0] - ext[j][0]) * (ext[j+1][1] + ext[j][1])
            
            # In my previous check, I said area < 0 is CCW.
            # Let's re-verify.
            # For (0,0), (1,0), (1,1), (0,1) -> area is -2.
            # For (0,0), (0,1), (1,1), (1,0) -> (0-0)*(1+0) + (1-0)*(1+1) + (1-1)*(0+1) + (0-1)*(0+0) = 0 + 2 + 0 + 0 = 2.
            # So CCW is area < 0, CW is area > 0.
            
            ext_ccw = area < 0
            if not ext_ccw:
                errors += 1
                
            for k, interior in enumerate(geom.interiors):
                int_coords = list(interior.coords)
                i_area = 0
                for j in range(len(int_coords)-1):
                    i_area += (int_coords[j+1][0] - int_coords[j][0]) * (int_coords[j+1][1] + int_coords[j][1])
                int_cw = i_area > 0
                if not int_cw:
                    errors += 1
    print(f"Total orientation errors found: {errors}")

check_rings('tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon

def fix_geometries(input_path, output_path):
    gdf = gpd.read_file(input_path)
    
    def fix_polygon(geom):
        if geom.is_empty:
            return geom
        if isinstance(geom, Polygon):
            # THE PROBLEM: I've been using area < 0 for CCW.
            # Let's use the area sign as a direct check.
            
            ext_coords = list(geom.exterior.coords)
            ext_area = 0
            for j in range(len(ext_coords)-1):
                ext_area += (ext_coords[j+1][0] - ext_coords[j][0]) * (ext_coords[j+1][1] + ext_coords[j][1])
            
            # If ext_area > 0, it is CW. We want CCW (area < 0).
            # If ext_area < 0, it is CCW. We want CCW.
            # Let's just flip if area > 0.
            if ext_area > 0:
                ext_coords = ext_coords[::-1]
                
            new_interiors = []
            for interior in geom.interiors:
                int_coords = list(interior.coords)
                int_area = 0
                for j in range(len(int_coords)-1):
                    int_area += (int_coords[j+1][0] - int_coords[j][0]) * (int_coords[j+1][1] + int_coords[j][1])
                
                # If int_area < 0, it is CCW. We want CW (area > 0).
                # If int_area > 0, it is CW. We want CW.
                if int_area < 0:
                    int_coords = int_coords[::-1]
                new_interiors.append(int_coords)
                
            return Polygon(ext_coords, new_interiors)
            
        elif isinstance(geom, MultiPolygon):
            return MultiPolygon([fix_polygon(p) for p in geom.geoms])
        return geom

    # Wait, I just noticed something in my manual check.
    # If I reverse a list like [1, 2, 3, 1], I get [1, 3, 2, 1].
    # That is correct.
    
    # Let's re-run the fixer.
    gdf['geometry'] = gdf['geometry'].apply(fix_polygon)
    gdf['geometry'] = gdf['geometry'].buffer(0)
    gdf.to_file(output_path, driver='GeoJSON')

if __name__ == "__main__":
    fix_geometries('tokyo_buildings_legacy.geojson', 'tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon

def check_rings(file_path):
    gdf = gpd.read_file(file_path)
    errors = 0
    for i, geom in enumerate(gdf.geometry):
        if isinstance(geom, Polygon):
            ext = list(geom.exterior.coords)
            area = 0
            for j in range(len(ext)-1):
                area += (ext[j+1][0] - ext[j][0]) * (ext[j+1][1] + ext[j][1])
            
            # In the previous version, I said area < 0 is CCW.
            # Let's re-verify with a simple CCW square: (0,0), (1,0), (1,1), (0,1)
            # x1=0, y1=0; x2=1, y2=0 => (1-0)*(0+0) = 0
            # x2=1, y2=0; x3=1, y3=1 => (1-1)*(1+0) = 0
            # x3=1, y3=1; x4=0, y4=1 => (0-1)*(1+1) = -2
            # x4=0, y4=1; x1=0, y1=0 => (0-0)*(0+1) = 0
            # Total area = -2. So yes, CCW is area < 0.
            
            ext_ccw = area < 0
            if not ext_ccw:
                errors += 1
                
            for k, interior in enumerate(geom.interiors):
                int_coords = list(interior.coords)
                i_area = 0
                for j in range(len(int_coords)-1):
                    i_area += (int_coords[j+1][0] - int_coords[j][0]) * (int_coords[j+1][1] + int_coords[j][1])
                int_cw = i_area > 0
                if not int_cw:
                    errors += 1
    print(f"Total orientation errors found: {errors}")

check_rings('tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon

def check_rings(file_path):
    gdf = gpd.read_file(file_path)
    errors = 0
    for i, geom in enumerate(gdf.geometry):
        if isinstance(geom, Polygon):
            ext = list(geom.exterior.coords)
            area = 0
            for j in range(len(ext)-1):
                area += (ext[j+1][0] - ext[j][0]) * (ext[j+1][1] + ext[j][1])
            
            # If area > 0, it is CW.
            # If area < 0, it is CCW.
            
            # Let's print the area for the first one
            if i == 0:
                print(f"First feature exterior area: {area}")

            ext_ccw = area < 0
            if not ext_ccw:
                errors += 1
                
            for k, interior in enumerate(geom.interiors):
                int_coords = list(interior.coords)
                i_area = 0
                for j in range(len(int_coords)-1):
                    i_area += (int_coords[j+1][0] - int_coords[j][0]) * (int_coords[j+1][1] + int_coords[j][1])
                int_cw = i_area > 0
                if not int_cw:
                    errors += 1
    print(f"Total orientation errors found: {errors}")

check_rings('tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon

def fix_geometries(input_path, output_path):
    gdf = gpd.read_file(input_path)
    
    def fix_polygon(geom):
        if geom.is_empty:
            return geom
        if isinstance(geom, Polygon):
            # The area is positive, so it's CW.
            # We want CCW (area < 0).
            # So we MUST reverse it.
            
            ext_coords = list(geom.exterior.coords)
            ext_area = 0
            for j in range(len(ext_coords)-1):
                ext_area += (ext_coords[j+1][0] - ext_coords[j][0]) * (ext_coords[j+1][1] + ext_coords[j][1])
            
            # If ext_area > 0 (CW), reverse to get CCW
            if ext_area > 0:
                ext_coords = ext_coords[::-1]
            # If ext_area < 0 (CCW), leave it.
            
            new_interiors = []
            for interior in geom.interiors:
                int_coords = list(interior.coords)
                int_area = 0
                for j in range(len(int_coords)-1):
                    int_area += (int_coords[j+1][0] - int_coords[j][0]) * (int_coords[j+1][1] + int_coords[j][1])
                
                # If int_area < 0 (CCW), reverse to get CW (int_area > 0)
                if int_area < 0:
                    int_coords = int_coords[::-1]
                new_interiors.append(int_coords)
                
            return Polygon(ext_coords, new_interiors)
            
        elif isinstance(geom, MultiPolygon):
            return MultiPolygon([fix_polygon(p) for p in geom.geoms])
        return geom

    gdf['geometry'] = gdf['geometry'].apply(fix_polygon)
    gdf['geometry'] = gdf['geometry'].buffer(0)
    gdf.to_file(output_path, driver='GeoJSON')

if __name__ == "__main__":
    fix_geometries('tokyo_buildings_legacy.geojson', 'tokyo_buildings_fixed.geojson')

import geopandas as gpd
from shapely.geometry import Polygon, MultiPolygon

def fix_geometries(input_path, output_path):
    gdf = gpd.read_file(input_path)
    
    def fix_polygon(geom):
        if geom.is_empty:
            return geom
        if isinstance(geom, Polygon):
            # In the legacy data, the area was positive (CW).
            # We want CCW (area < 0).
            # BUT wait, my shoelace formula might be returning positive for CCW.
            # Let's check (0,0), (1,0), (1,1), (0,1) again.
            # (1-0)*(0+0) + (1-1)*(1+0) + (0-1)*(1+1) + (0-0)*(0+1) = 0 + 0 + -2 + 0 = -2.
            # So CCW is indeed negative.
            # If the legacy area is 1.15e-08, it's positive, which means it's CW.
            # So my fix (reversing if area > 0) should have worked.
            # Why did verify_final_v8 still say 105 errors?
            
            # Let's check if Polygon(ext_coords, new_interiors) is even working.
            # Shapely might be re-orienting it!
            
            ext_coords = list(geom.exterior.coords)
            ext_area = 0
            for j in range(len(ext_coords)-1):
                ext_area += (ext_coords[j+1][0] - ext_coords[j][0]) * (ext_coords[j+1][1] + ext_coords[j][1])
            
            if ext_area > 0:
                ext_coords = ext_coords[::-1]
            
            new_interiors = []
            for interior in geom.interiors:
                int_coords = list(interior.coords)
                int_area = 0
                for j in range(len(int_coords)-1):
                    int_area += (int_coords[j+1][0] - int_coords[j][0]) * (int_coords[j+1][1] + int_coords[j][1])
                if int_area < 0:
                    int_coords = int_coords[::-1]
                new_interiors.append(int_coords)
            
            return Polygon(ext_coords, new_interiors)
            
        elif isinstance(geom, MultiPolygon):
            return MultiPolygon([fix_polygon(p) for p in geom.geoms])
        return geom

    # NEW APPROACH: Use the orient() function from shapely correctly.
    # It is designed for this.
    # orient(polygon, sign=1.0) makes exterior CCW and interior CW.
    # If orient() is not working, it's probably because the geometries are 
    # considered invalid or something.
    
    gdf['geometry'] = gdf['geometry'].apply(lambda g: orient(g, sign=1.0))
    gdf.to_file(output_path, driver='GeoJSON')

from shapely.ops import orient

if __name__ == "__main__":
    fix_geometries('tokyo_buildings_legacy.geojson', 'tokyo_buildings_fixed.geojson')