dc-l1-tokyo-ring-orientation
Map (reference ← swipe → agent)
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tokyo_buildings_legacy.geojson is a footprint export from an old in-house tool. When we load it into web-based GeoJSON viewers, building interiors are shaded incorrectly: holes appear filled and exteriors render as empty space. Our tile-server import script also rejects every feature with geometry warnings. Fix the geometries so that standard GeoJSON web viewers render them correctly. Attributes must be untouched. Output to tokyo_buildings_fixed.geojson.
Every feature must remain a Polygon with interior rings and holes preserved exactly as they are; do not flatten them. feature_id is the join key.
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System info
{
"adapter": "openrouter",
"model": "google/gemma-4-26b-a4b-it",
"base_url": "https://openrouter.ai/api/v1"
}
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Bash
ls -F
tokyo_buildings_legacy.geojson
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Bash
head -n 20 tokyo_buildings_legacy.geojson
{
"type": "FeatureCollection",
"name": "tokyo_buildings_legacy",
"crs": {
"type": "name",
"properties": {
"name": "urn:ogc:def:crs:OGC:1.3:CRS84"
}
},
"features": [
{
"type": "Feature",
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
139.7029081,
35.6592372
],
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Write
/work/solve.py
content · 48 lines · py
import geopandas as gpd
# Load the data
gdf = gpd.read_file('tokyo_buildings_legacy.geojson')
# Print initial info
print(f"Loaded {len(gdf)} features.")
print(gdf.head())
# Check for invalid geometries
invalid_count = (~gdf.is_valid).sum()
print(f"Invalid geometries: {invalid_count}")
# The problem description says "building interiors are shaded incorrectly: holes appear filled and exteriors render as empty space."
# This usually means the winding order of the rings is incorrect.
# For GeoJSON (RFC 7946), the exterior ring should be counter-clockwise and interior rings should be clockwise.
# However, many GIS tools use different conventions.
# Let's try to fix the orientation.
# Shapely's orient function can fix winding order.
from shapely.geometry import Polygon, MultiPolygon
from shapely.ops import orient
def fix_geometry(geom):
if geom.is_empty:
return geom
if isinstance(geom, Polygon):
# orient(polygon, sign=1.0) makes exterior ring CCW and interior rings CW
return orient(geom, sign=1.0)
elif isinstance(geom, MultiPolygon):
return MultiPolygon([orient(p, sign=1.0) for p in geom.geoms])
else:
return geom
# Apply the orientation fix
gdf['geometry'] = gdf['geometry'].apply(fix_geometry)
# Also ensure they are valid (buffer(0) is a common trick, but orient should be enough for winding)
gdf['geometry'] = gdf['geometry'].buffer(0)
# Check invalid geometries again
invalid_count = (~gdf.is_valid).sum()
print(f"Invalid geometries after fix: {invalid_count}")
# Save the fixed file
gdf.to_file('tokyo_buildings_fixed.geojson', driver='GeoJSON')
print("Successfully saved tokyo_buildings_fixed.geojson")
Wrote /work/solve.py (1687 chars).
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Bash
python solve.py
Loaded 100 features. feature_id ... geometry 0 1 ... POLYGON ((139.70291 35.65924, 139.7028 35.6592... 1 2 ... POLYGON ((139.70109 35.6602, 139.70109 35.6600... 2 3 ... POLYGON ((139.70112 35.66167, 139.70099 35.661... 3 4 ... POLYGON ((139.70327 35.66018, 139.7033 35.6601... 4 5 ... POLYGON ((139.70158 35.6592, 139.70161 35.6592... [5 rows x 6 columns] Invalid geometries: 0 Invalid geometries after fix: 0 Successfully saved tokyo_buildings_fixed.geojson
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Write
/work/validate.py
content · 65 lines · py
import geopandas as gpd
import json
# Load original
gdf_orig = gpd.read_file('tokyo_buildings_legacy.geojson')
# Load fixed
gdf_fixed = gpd.read_file('tokyo_buildings_fixed.geojson')
# 1. Check feature count
print(f"Original count: {len(gdf_orig)}")
print(f"Fixed count: {len(gdf_fixed)}")
# 2. Check feature_id preservation (and alignment)
# We'll assume feature_id is the join key as per instructions.
gdf_orig = gdf_orig.sort_values('feature_id')
gdf_fixed = gdf_fixed.sort_values('feature_id')
if not gdf_orig['feature_id'].equals(gdf_fixed['feature_id']):
print("ERROR: feature_id mismatch!")
else:
print("SUCCESS: feature_id preserved.")
# 3. Check attributes
# Get column names (excluding geometry)
orig_cols = [c for c in gdf_orig.columns if c != 'geometry']
fixed_cols = [c for c in gdf_fixed.columns if c != 'geometry']
if set(orig_cols) != set(fixed_cols):
print(f"ERROR: Attribute mismatch. Original: {orig_cols}, Fixed: {fixed_cols}")
else:
print("SUCCESS: Attributes preserved.")
# Compare a sample of attributes
for i in range(min(5, len(gdf_orig))):
for col in orig_cols:
if gdf_orig.iloc[i][col] != gdf_fixed.iloc[i][col]:
print(f"ERROR: Attribute mismatch at index {i}, col {col}")
break
else:
continue
break
else:
print("SUCCESS: Sample attributes match.")
# 4. Check geometry structure (not values, but types)
# We want to ensure they didn't flatten holes.
def check_rings(geom):
if geom.is_empty: return 0
if geom.geom_type == 'Polygon':
return 1 + len(geom.interiors)
if geom.geom_type == 'MultiPolygon':
return sum(1 + len(p.interiors) for p in geom.geoms)
return 0
orig_rings = gdf_orig['geometry'].apply(check_rings).sum()
fixed_rings = gdf_fixed['geometry'].apply(check_rings).sum()
print(f"Total rings (exterior + interior) original: {orig_rings}")
print(f"Total rings (exterior + interior) fixed: {fixed_rings}")
if orig_rings != fixed_rings:
print("ERROR: Geometry structure changed (rings lost)!")
else:
print("SUCCESS: Geometry structure preserved.")
Wrote /work/validate.py (2107 chars).
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Bash
python validate.py
Original count: 100 Fixed count: 100 SUCCESS: feature_id preserved. SUCCESS: Attributes preserved. ERROR: Attribute mismatch at index 0, col height Total rings (exterior + interior) original: 105 Total rings (exterior + interior) fixed: 105 SUCCESS: Geometry structure preserved.
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Write
/work/debug_attr.py
content · 24 lines · py
import geopandas as gpd
import json
# Load original
gdf_orig = gpd.read_file('tokyo_buildings_legacy.geojson')
# Load fixed
gdf_fixed = gpd.read_file('tokyo_buildings_fixed.geojson')
# Print all attributes of the first feature to inspect
print("Original feature 0 attributes:")
print(gdf_orig.iloc[0].to_dict())
print("\nFixed feature 0 attributes:")
print(gdf_fixed.iloc[0].to_dict())
# Let's re-examine the mismatch
idx = 0
col = 'height'
val_orig = gdf_orig.iloc[idx][col]
val_fixed = gdf_fixed.iloc[idx][col]
print(f"\nMismatch in '{col}' at index {idx}: {val_orig} vs {val_fixed}")
# Check types
print(f"Type orig: {type(val_orig)}, Type fixed: {type(val_fixed)}")
Wrote /work/debug_attr.py (674 chars).
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Bash
python debug_attr.py
Original feature 0 attributes:
{'feature_id': 1, 'overture_id': '01302ced-3141-4b64-b630-98019352a9fd', 'name_primary': '渋谷協和ビル', 'building_class': '', 'height': nan, 'geometry': <POLYGON ((139.703 35.659, 139.703 35.659, 139.703 35.659, 139.703 35.659, 1...>}
Fixed feature 0 attributes:
{'feature_id': 1, 'overture_id': '01302ced-3141-4b64-b630-98019352a9fd', 'name_primary': '渋谷協和ビル', 'building_class': '', 'height': nan, 'geometry': <POLYGON ((139.703 35.659, 139.703 35.659, 139.703 35.659, 139.703 35.659, 1...>}
Mismatch in 'height' at index 0: nan vs nan
Type orig: <class 'numpy.float64'>, Type fixed: <class 'numpy.float64'>
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Write
/work/final_validate.py
content · 24 lines · py
import geopandas as gpd
import numpy as np
# Load original
gdf_orig = gpd.read_file('tokyo_buildings_legacy.geojson')
# Load fixed
gdf_fixed = gpd.read_file('tokyo_buildings_fixed.geojson')
# Check if nan == nan is causing the "mismatch" in my validation script
def compare_dfs(df1, df2):
# Comparing only non-geometry columns
cols = [c for c in df1.columns if c != 'geometry']
# Use pandas testing to see if they are identical
import pandas as pd
try:
pd.testing.assert_frame_equal(df1[cols], df2[cols], check_dtype=False)
print("SUCCESS: DataFrames are identical (using pd.testing.assert_frame_equal)")
except AssertionError as e:
print("ERROR: DataFrames are not identical:")
print(e)
compare_dfs(gdf_orig, gdf_fixed)
Wrote /work/final_validate.py (785 chars).
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Bash
python final_validate.py
SUCCESS: DataFrames are identical (using pd.testing.assert_frame_equal)
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Bash
rm /work/solve.py /work/validate.py /work/debug_attr.py /work/final_validate.py
(no output)
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