Light pollution data

1def create_scatter_kernel():2    """Atmospheric scatter PSF. Center zeroed (no self-scatter)."""3    radius_px = int(MAX_RADIUS_KM / PIXEL_KM) + 14    size = 2 * radius_px + 15    kernel = np.zeros((size, size), dtype=np.float64)6    c = radius_px78    for y in range(size):9        for x in range(size):10            d = math.sqrt(((y - c) * PIXEL_KM)**2 + ((x - c) * PIXEL_KM)**2)11            if d < 0.5 or d > MAX_RADIUS_KM:12                continue13            kernel[y, x] = (SCATTER_FRACTION *14                            math.exp(-d / SCATTER_SCALE_KM) /15                            (1.0 + (d / D_REF_KM) ** SCATTER_POWER))16    return kernel.astype(np.float32)

1def write_zones_db(accum_path, output_path):2    conn = sqlite3.connect(str(accum_path))3    total = conn.execute('SELECT COUNT(*) FROM cells').fetchone()[0]4    print(f"\nWriting {total:,} cells to {output_path}")56    written = 07    skipped = 089    with open(output_path, 'wb') as f:10        f.write(b'ASTR\x01\x00\x00\x00')11        count_pos = f.tell()12        f.write(struct.pack('<Q', 0))1314        cursor = conn.execute('SELECT h3, radiance FROM cells ORDER BY h3')15        while True:16            rows = cursor.fetchmany(100_000)17            if not rows: break18            for h3_int, rad in rows:19                zone = radiance_to_zone(rad)20                if zone <= 1:21                    skipped += 1; continue22                sqm = radiance_to_sqm(rad)23                f.write(struct.pack('<Q', h3_int))24                f.write(struct.pack('B', zone))25                f.write(struct.pack('<f', rad))26                f.write(struct.pack('<f', sqm))27                f.write(b'\x00\x00\x00')28                written += 12930        f.seek(count_pos)31        f.write(struct.pack('<Q', written))3233    sha = hashlib.sha256()34    with open(output_path, 'rb') as f:35        for chunk in iter(lambda: f.read(8192), b''): sha.update(chunk)3637    size_mb = output_path.stat().st_size / (1024**2)38    print(f"\n{'='*50}")39    print(f"SUCCESS!")40    print(f"  Records: {written:,} (skipped {skipped:,} Zone 1)")41    print(f"  Size: {size_mb:.1f} MB")42    print(f"  SHA-256: {sha.hexdigest()}")43    print(f"{'='*50}")4445    # Quick validation46    print("\nValidation:")47    for name, lat, lon in [48        ("Bhadraj Temple", 30.5167, 78.0333),49        ("Dehradun", 30.3165, 78.0322),50        ("Hanle", 32.7795, 78.9641),51        ("New York City", 40.7128, -74.0060),52        ("Null Island", 0.0, 0.0),53    ]:54        h3_cell = h3.latlng_to_cell(lat, lon, H3_RESOLUTION)55        h3_int = int(h3_cell, 16)56        row = conn.execute('SELECT radiance FROM cells WHERE h3=?', (h3_int,)).fetchone()57        if row:58            z = radiance_to_zone(row[0])59            print(f"  {name}: Zone {z} (radiance={row[0]:.4f})")60        else:61            print(f"  {name}: Zone 1 (Implicit)")6263    conn.close()

1/**2 * Look up zone data for a given H3 hex index.3 * 4 * D1 table schema:5 *   zones(h3 INTEGER PRIMARY KEY, zone INTEGER, radiance REAL, sqm REAL)6 * 7 * "h3" is stored as a signed 64-bit integer (SQLite INTEGER).8 * We convert the hex string to a BigInt, then to a signed int for SQL.9 */10async function handleZoneLookup(h3Hex, env) {11    try {12        // Convert hex to BigInt, then to signed 64-bit for D1 (SQLite stores signed)13        const h3BigInt = BigInt('0x' + h3Hex);1415        // Convert unsigned to signed 64-bit representation16        const h3Signed = toSigned64(h3BigInt);1718        const row = await env.DB.prepare(19            'SELECT zone, radiance, sqm FROM zones WHERE h3 = ?'20        ).bind(h3Signed.toString()).first();2122        if (row) {23            return jsonResponse({24                bortle: row.zone,25                ratio: Math.round(row.radiance * 100) / 100,26                sqm: Math.round(row.sqm * 100) / 100,27                h3: h3Hex,28            }, 200, {29                'Cache-Control': `public, max-age=${CACHE_TTL}`,30            });31        }3233        // Not found → Zone 1 (pristine dark sky)34        return jsonResponse({35            bortle: 1,36            ratio: 0.0,37            sqm: 22.0,38            h3: h3Hex,39            implicit: true,40        }, 200, {41            'Cache-Control': `public, max-age=${CACHE_TTL}`,42        });4344    } catch (error) {45        console.error('Zone lookup error:', error);46        return jsonResponse({ error: 'Internal server error' }, 500);47    }48}

1/**2 * Convert an unsigned 64-bit BigInt to signed 64-bit representation.3 * 4 * SQLite/D1 stores INTEGER as signed. H3 indices use the full unsigned5 * 64-bit range, so values with the high bit set appear negative in SQL.6 */7function toSigned64(unsigned) {8    const MAX_UINT64 = (1n << 64n) - 1n;9    const MAX_INT64 = (1n << 63n) - 1n;1011    if (unsigned > MAX_UINT64) {12        throw new Error('Value exceeds uint64 range');13    }1415    if (unsigned > MAX_INT64) {16        // High bit set → negative in signed representation17        return unsigned - (1n << 64n);18    }1920    return unsigned;21}

1/// Fetches zone data for the given H3 index from remote API.2///3/// Returns:4/// - [ZoneData] on success5/// - `null` on network error, timeout, or 404 (not found)6///7/// Throws: Nothing - all errors are caught and return null for graceful fallback.8Future<ZoneData?> getZoneData(BigInt h3Index) async {9  final String h3Hex = h3Index.toRadixString(16);10  final Uri uri = Uri.parse('$_baseUrl/zone/$h3Hex');1112  try {13    final http.Response response = await _client14        .get(uri)15        .timeout(_timeout);1617    if (response.statusCode == 200) {18      final Map<String, dynamic> json = 19          jsonDecode(response.body) as Map<String, dynamic>;20      21      return ZoneData(22        astrZone: (json['bortle'] as num).toInt(),23        ratio: (json['ratio'] as num).toDouble(),24        sqm: (json['sqm'] as num).toDouble(),25      );26    } else if (response.statusCode == 404) {27      // H3 index not found in database - expected for ocean/unpopulated areas28      debugPrint('Zone not found for H3 $h3Hex');29      return null;30    } else {31      debugPrint('Zone API error: ${response.statusCode}');32      return null;33    }34  } catch (e) {35    debugPrint('Zone API request failed: $e');36    return null;37  }38}

1/// Get zone data for an H3 index, using cache-first strategy.2///3/// Returns:4/// - [ZoneData] from cache or remote API5/// - [pristineDarkSky] if not found in database (dark sky location!)6Future<ZoneData> getZoneData(BigInt h3Index) async {7  final String h3Hex = h3Index.toRadixString(16);8  final String cacheKey = '$_keyPrefix$h3Hex';910  // 1. Check cache first11  final ZoneCacheEntry? cached = _cache.get(cacheKey);12  if (cached != null && !cached.isExpired) {13    debugPrint('Zone cache hit for $h3Hex');14    return ZoneData(15      astrZone: cached.astrZone,16      ratio: cached.ratio,17      sqm: cached.sqm,18    );19  }2021  // 2. Cache miss — fetch from remote D1 API22  debugPrint('Zone cache miss for $h3Hex, fetching from remote...');23  final ZoneData? remoteData = await _remote.getZoneData(h3Index);2425  if (remoteData != null) {26    _cacheZoneData(cacheKey, h3Hex, remoteData);27    return remoteData;28  }2930  // 3. Remote failed - check if we have stale cache31  if (cached != null) {32    debugPrint('Remote failed, using expired cache for $h3Hex');33    return ZoneData(34      astrZone: cached.astrZone,35      ratio: cached.ratio,36      sqm: cached.sqm,37    );38  }3940  // 4. Not in database = pristine dark sky location41  debugPrint('$h3Hex not in lit-areas DB, returning pristine dark sky');42  return pristineDarkSky;43}