scripts/melbourne/Obtain_corresponding_map_signed.py

"""Fetch per-tile imagery and derive semantic masks for the City3D-MultiGen
reconstruction pipeline (GridFlow, ECCV 2026).

Pipeline role:
    For each 150 m tile this script downloads two co-registered rasters from the
    signed Google Maps Static API -- a satellite image and a custom-styled
    "roadmap" image -- then parses the styled roadmap into per-class binary
    semantic masks using fixed color thresholds.

Inputs:
    Tile geo-extents read from per-tile JSON metadata files (``wgs84_nw`` /
    ``wgs84_se`` lon/lat corners). These JSONs can optionally be generated first
    from an area bounding box (``--nw`` / ``--se``).

Outputs (written next to each JSON, keyed by the tile base name):
    ``<base>_sat.png``  satellite crop, ``<base>_map.png`` styled roadmap crop,
    and six mask images ``<base>_<Class>.png`` for the classes Building,
    RoadSurface, Railway, VegetationLand, UrbanLand and WaterSurface.

Key steps:
    1. Build the Static Maps URL, sign it with the URL-signing secret (HMAC-SHA1).
    2. Fetch satellite and styled-roadmap tiles, then crop to the exact extent.
    3. Parse the roadmap crop into masks via the CLASS_COLORS_HEX color thresholds
       (exact match per class; tolerant match plus 1 px dilation for Railway).

Required environment variables (each may be overridden by a CLI flag):
    GOOGLE_MAPS_API_KEY              Static Maps API key.
    GOOGLE_MAPS_URL_SIGNING_SECRET  URL-signing secret for the signed requests.
    GOOGLE_MAPS_STYLE_MAP_ID        Map ID of the custom roadmap style.

Note: the custom Google map style referenced by GOOGLE_MAPS_STYLE_MAP_ID is not
distributed here; you must recreate it in the Google Cloud console so the styled
roadmap colors match the CLASS_COLORS_HEX values used for mask parsing.
"""

import os
import json
import math
import io
import time
import argparse
import requests
from requests.adapters import HTTPAdapter
from urllib3.util.retry import Retry
from PIL import Image
import numpy as np
from tqdm import tqdm
import hashlib
import hmac
import base64
import urllib.parse as urlparse
from pyproj import Transformer

CLASS_COLORS_HEX = {
    "RoadSurface":      ["1e1e1e"],
    "Building":         ["ff0000"],
    "Railway":          ["0073ff"],
    "VegetationLand":   ["c3f1d5"],
    "UrbanLand":        ["f5f0e5", "d3f8e2"],
    "WaterSurface":     ["90daee"],
}

def hex_to_rgb(hex_str):
    h = hex_str.strip().lower()
    return (
        int(h[0:2], 16),
        int(h[2:4], 16),
        int(h[4:6], 16),
    )

CLASS_COLORS_RGB = {
    class_name: [hex_to_rgb(code) for code in hex_list]
    for class_name, hex_list in CLASS_COLORS_HEX.items()
}

def sign_url(input_url, secret):
    if not input_url or not secret:
        raise Exception("Both input_url and secret are required")

    url = urlparse.urlparse(input_url)
    url_to_sign = url.path + "?" + url.query
    decoded_key = base64.urlsafe_b64decode(secret)
    signature = hmac.new(decoded_key, str.encode(url_to_sign), hashlib.sha1)
    encoded_signature = base64.urlsafe_b64encode(signature.digest())
    original_url = url.scheme + "://" + url.netloc + url.path + "?" + url.query
    return original_url + "&signature=" + encoded_signature.decode()

def dilate_mask_1px(mask_arr):
    h, w = mask_arr.shape
    out = np.zeros((h, w), dtype=np.uint8)
    ys, xs = np.nonzero(mask_arr > 0)
    for y, x in zip(ys, xs):
        y0 = max(y - 1, 0)
        y1 = min(y + 1, h - 1)
        x0 = max(x - 1, 0)
        x1 = min(x + 1, w - 1)
        out[y0:y1+1, x0:x1+1] = 255
    return out

def match_mask_exact(arr, rgb_triplet):
    r, g, b = rgb_triplet
    return (
        (arr[:, :, 0] == r) &
        (arr[:, :, 1] == g) &
        (arr[:, :, 2] == b)
    )

def channel_bounds_with_margin(channel_val, margin_ratio):
    low = int(round(channel_val * (1.0 - margin_ratio)))
    high = int(round(channel_val * (1.0 + margin_ratio)))
    if low < 0:
        low = 0
    if high > 255:
        high = 255
    return low, high

def match_mask_tolerant(arr, rgb_triplet, margin_ratio):
    r, g, b = rgb_triplet
    rl, rh = channel_bounds_with_margin(r, margin_ratio)
    gl, gh = channel_bounds_with_margin(g, margin_ratio)
    bl, bh = channel_bounds_with_margin(b, margin_ratio)
    return (
        (arr[:, :, 0] >= rl) & (arr[:, :, 0] <= rh) &
        (arr[:, :, 1] >= gl) & (arr[:, :, 1] <= gh) &
        (arr[:, :, 2] >= bl) & (arr[:, :, 2] <= bh)
    )

def generate_masks_from_roadmap(crop_road_img, base_output_path_no_ext):
    rgb = crop_road_img.convert("RGB")
    arr = np.array(rgb, dtype=np.uint8)

    for class_name, rgb_list in CLASS_COLORS_RGB.items():
        class_mask_total = np.zeros(arr.shape[:2], dtype=np.uint8)

        for rgb_triplet in rgb_list:
            if class_name == "Railway":
                match = match_mask_tolerant(arr, rgb_triplet, margin_ratio=0.1)
            else:
                match = match_mask_exact(arr, rgb_triplet)
            class_mask_total[match] = 255

        if class_name == "Railway":
            class_mask_total = dilate_mask_1px(class_mask_total)

        out_path = f"{base_output_path_no_ext}_{class_name}.png"
        img = Image.fromarray(class_mask_total)
        img.save(out_path)

def save_bbox_satellite_and_roadmap(
    north_lat,
    west_lon,
    south_lat,
    east_lon,
    out_path_sat,
    out_path_road,
    api_key,
    url_signing_secret,
    style_map_id
):
    def mercator_project(lon_deg, lat_deg, zoom):
        scale = 256 * (2 ** zoom)
        x = (lon_deg + 180.0) / 360.0 * scale
        lat_rad = math.radians(lat_deg)
        y = (1.0 - math.log(math.tan(lat_rad) + 1.0 / math.cos(lat_rad)) / math.pi) / 2.0 * scale
        return x, y

    def bbox_center(n_lat, s_lat, w_lon, e_lon):
        return (
            (n_lat + s_lat) / 2.0,
            (w_lon + e_lon) / 2.0
        )

    def download_static(center_lat, center_lon, zoom, size_px, maptype, api_key, url_signing_secret, style_map_id=None):
        session = requests.Session()
        retry_strategy = Retry(
            total=5,
            backoff_factor=2,
            status_forcelist=[429, 500, 502, 503, 504],
            allowed_methods=["GET"]
        )
        adapter = HTTPAdapter(max_retries=retry_strategy)
        session.mount("https://", adapter)
        session.mount("http://", adapter)
        
        base = "https://maps.googleapis.com/maps/api/staticmap"
        params = {
            "center": f"{center_lat},{center_lon}",
            "zoom": str(18),
            "size": f"{size_px}x{size_px}",
            "format": "png",
            "key": api_key,
        }
        if maptype == "satellite":
            params["maptype"] = "satellite"
        else:
            params["map_id"] = style_map_id
        
        query_string = "&".join([f"{k}={urlparse.quote(str(v), safe='')}" for k, v in params.items()])
        unsigned_url = f"{base}?{query_string}"
        signed_url = sign_url(unsigned_url, url_signing_secret)
        
        max_retries = 3
        for attempt in range(max_retries):
            try:
                resp = session.get(signed_url, timeout=30)
                resp.raise_for_status()
                time.sleep(0.5)
                return Image.open(io.BytesIO(resp.content)).convert("RGBA")
            except (requests.exceptions.ConnectionError, 
                    requests.exceptions.Timeout,
                    requests.exceptions.RequestException) as e:
                if attempt < max_retries - 1:
                    wait_time = (attempt + 1) * 5
                    print(f"\nRequest failed, retrying in {wait_time} seconds...")
                    time.sleep(wait_time)
                else:
                    raise

    def crop_bbox_from_image(img, zoom, img_px, center_lat, center_lon,
                             n_lat, s_lat, w_lon, e_lon):
        center_x, center_y = mercator_project(center_lon, center_lat, zoom)
        img_left_world  = center_x - img_px / 2.0
        img_top_world   = center_y - img_px / 2.0

        w_x, _ = mercator_project(w_lon, center_lat, zoom)
        e_x, _ = mercator_project(e_lon, center_lat, zoom)
        _, n_y = mercator_project(center_lon, n_lat, zoom)
        _, s_y = mercator_project(center_lon, s_lat, zoom)

        xmin = w_x - img_left_world
        xmax = e_x - img_left_world
        ymin = n_y - img_top_world
        ymax = s_y - img_top_world

        box = (
            int(round(xmin)),
            int(round(ymin)),
            int(round(xmax)),
            int(round(ymax)),
        )

        box = (
            max(0, box[0]),
            max(0, box[1]),
            min(img_px, box[2]),
            min(img_px, box[3]),
        )

        return img.crop(box)

    zoom = 18
    img_px = 600

    center_lat, center_lon = bbox_center(north_lat, south_lat, west_lon, east_lon)

    img_sat = download_static(center_lat, center_lon, zoom, img_px, "satellite", api_key, url_signing_secret, style_map_id=None)
    img_road = download_static(center_lat, center_lon, zoom, img_px, "roadmap", api_key, url_signing_secret, style_map_id=style_map_id)

    crop_sat = crop_bbox_from_image(
        img_sat, zoom, img_px, center_lat, center_lon,
        north_lat, south_lat, west_lon, east_lon
    )
    crop_road = crop_bbox_from_image(
        img_road, zoom, img_px, center_lat, center_lon,
        north_lat, south_lat, west_lon, east_lon
    )

    crop_sat.save(out_path_sat)
    crop_road.save(out_path_road)

    return crop_sat, crop_road

def process_folder(
    folder_path,
    api_key,
    url_signing_secret,
    style_map_id
):
    json_files = [f for f in os.listdir(folder_path) if f.lower().endswith(".json")]
    
    skipped = 0
    failed = 0
    failed_files = []
    
    for filename in tqdm(json_files, desc="Processing files", unit="file"):
        try:
            json_path = os.path.join(folder_path, filename)
            base_name = os.path.splitext(filename)[0]

            out_sat = os.path.join(folder_path, base_name + "_sat.png")
            out_map = os.path.join(folder_path, base_name + "_map.png")
            
            expected_files = [out_sat, out_map]
            for class_name in CLASS_COLORS_RGB.keys():
                expected_files.append(os.path.join(folder_path, f"{base_name}_{class_name}.png"))
            
            if all(os.path.exists(f) for f in expected_files):
                skipped += 1
                continue

            with open(json_path, "r", encoding="utf-8") as f:
                data = json.load(f)

            wgs84_nw = data["wgs84_nw"]
            wgs84_se = data["wgs84_se"]

            west_lon  = float(wgs84_nw[0])
            north_lat = float(wgs84_nw[1])
            east_lon  = float(wgs84_se[0])
            south_lat = float(wgs84_se[1])

            crop_sat, crop_road = save_bbox_satellite_and_roadmap(
                north_lat = north_lat,
                west_lon  = west_lon,
                south_lat = south_lat,
                east_lon  = east_lon,
                out_path_sat  = out_sat,
                out_path_road = out_map,
                api_key       = api_key,
                url_signing_secret = url_signing_secret,
                style_map_id  = style_map_id
            )

            base_mask_prefix = os.path.join(folder_path, base_name)
            generate_masks_from_roadmap(crop_road, base_mask_prefix)
            
        except Exception as e:
            failed += 1
            failed_files.append(filename)
            print(f"\nFailed to process {filename}: {str(e)}")
            continue
    
    print(f"\nProcessing complete!")
    if skipped > 0:
        print(f"Skipped {skipped} already processed files")
    if failed > 0:
        print(f"Failed to process {failed} files:")
        for f in failed_files:
            print(f"  - {f}")

def make_utm_transformers(center_lat, center_lon):
    zone = int((center_lon + 180) / 6) + 1
    epsg = (32600 if center_lat >= 0 else 32700) + zone
    to_utm = Transformer.from_crs("EPSG:4326", f"EPSG:{epsg}", always_xy=True)
    to_wgs = Transformer.from_crs(f"EPSG:{epsg}", "EPSG:4326", always_xy=True)
    return to_utm, to_wgs, epsg


def generate_tile_metadata_for_area(
    nw_lat,
    nw_lon,
    se_lat,
    se_lon,
    output_folder,
    tile_size_m=150.0,
    grid_step_m=20.0,
    grid_id_start=0,
    overwrite=False,
):
    """Tile a lat/lon bounding box into JSON metadata files compatible with
    the Melbourne dataset format (utm_nw / utm_se / wgs84_nw / wgs84_se / row / col).

    Args:
        nw_lat, nw_lon: northwest corner of the area (degrees).
        se_lat, se_lon: southeast corner of the area (degrees).
        output_folder: where JSON files will be written.
        tile_size_m: edge length of each tile in meters (default 150, matches dataset).
        grid_step_m: spacing between adjacent tile centers (default 20, matches dataset).
        grid_id_start: starting grid_id for filenames (grid_NNNNNN).
        overwrite: if False, existing JSONs are kept.

    Returns:
        list of file paths to the generated JSON files.
    """
    os.makedirs(output_folder, exist_ok=True)

    center_lat = (nw_lat + se_lat) / 2.0
    center_lon = (nw_lon + se_lon) / 2.0
    to_utm, to_wgs, epsg = make_utm_transformers(center_lat, center_lon)

    nw_x, nw_y = to_utm.transform(nw_lon, nw_lat)
    se_x, se_y = to_utm.transform(se_lon, se_lat)
    x_min, x_max = min(nw_x, se_x), max(nw_x, se_x)
    y_min, y_max = min(nw_y, se_y), max(nw_y, se_y)

    half = tile_size_m / 2.0
    n_cols = max(1, int(math.ceil((x_max - x_min) / grid_step_m)))
    n_rows = max(1, int(math.ceil((y_max - y_min) / grid_step_m)))

    print(f"Area UTM (EPSG:{epsg}): x=[{x_min:.1f},{x_max:.1f}] "
          f"y=[{y_min:.1f},{y_max:.1f}]")
    print(f"Extent: {x_max-x_min:.0f}m x {y_max-y_min:.0f}m  "
          f"-> grid {n_rows} rows x {n_cols} cols  "
          f"({n_rows*n_cols} tiles, step={grid_step_m}m, tile={tile_size_m}m)")

    written = []
    grid_id = grid_id_start
    for row in range(n_rows):
        cy = y_max - half - row * grid_step_m
        for col in range(n_cols):
            cx = x_min + half + col * grid_step_m

            utm_nw = [cx - half, cy + half]
            utm_se = [cx + half, cy - half]
            nw_lon_wgs, nw_lat_wgs = to_wgs.transform(utm_nw[0], utm_nw[1])
            se_lon_wgs, se_lat_wgs = to_wgs.transform(utm_se[0], utm_se[1])

            base_name = f"grid_{grid_id:06d}"
            out_path = os.path.join(output_folder, base_name + ".json")
            if os.path.exists(out_path) and not overwrite:
                grid_id += 1
                written.append(out_path)
                continue

            meta = {
                "grid_id": grid_id,
                "row": row,
                "col": col,
                "utm_nw": utm_nw,
                "utm_se": utm_se,
                "wgs84_nw": [nw_lon_wgs, nw_lat_wgs],
                "wgs84_se": [se_lon_wgs, se_lat_wgs],
                "utm_epsg": epsg,
                "elevation": {
                    "local_min_elevation": 0.0,
                    "local_max_elevation": 0.0,
                    "global_min_used": -20.0,
                    "global_max_used": 302.0,
                    "elevation_range": 0.0,
                },
            }
            with open(out_path, "w", encoding="utf-8") as f:
                json.dump(meta, f, indent=2)
            written.append(out_path)
            grid_id += 1

    print(f"Wrote {len(written)} tile JSONs to {output_folder}")
    return written


if __name__ == "__main__":
    parser = argparse.ArgumentParser(
        description="Fetch satellite + styled-roadmap tiles and class masks "
                    "for an area (DSM/point-cloud not generated)."
    )
    parser.add_argument("--folder", default="./output",
                        help="Output folder. If --nw/--se given, JSONs are "
                             "created here first; otherwise existing JSONs "
                             "in this folder are processed.")
    parser.add_argument("--nw", default=None,
                        help="Northwest corner 'lat,lon' (e.g. -37.778,144.932).")
    parser.add_argument("--se", default=None,
                        help="Southeast corner 'lat,lon' (e.g. -37.785,144.948).")
    parser.add_argument("--tile_size", type=float, default=150.0,
                        help="Tile edge length in meters (default 150).")
    parser.add_argument("--grid_step", type=float, default=20.0,
                        help="Spacing between tile centers in meters "
                             "(default 20 = dense dataset grid). Use a value "
                             "close to --tile_size for non-overlapping coverage "
                             "with far fewer API calls.")
    parser.add_argument("--grid_id_start", type=int, default=0)
    parser.add_argument("--api_key",
                        default=os.environ.get("GOOGLE_MAPS_API_KEY"))
    parser.add_argument("--url_signing_secret",
                        default=os.environ.get("GOOGLE_MAPS_URL_SIGNING_SECRET"))
    parser.add_argument("--style_map_id",
                        default=os.environ.get("GOOGLE_MAPS_STYLE_MAP_ID"))
    args = parser.parse_args()

    if (args.nw is None) ^ (args.se is None):
        parser.error("--nw and --se must be provided together.")

    if args.nw and args.se:
        nw_lat, nw_lon = [float(v) for v in args.nw.split(",")]
        se_lat, se_lon = [float(v) for v in args.se.split(",")]
        generate_tile_metadata_for_area(
            nw_lat=nw_lat, nw_lon=nw_lon,
            se_lat=se_lat, se_lon=se_lon,
            output_folder=args.folder,
            tile_size_m=args.tile_size,
            grid_step_m=args.grid_step,
            grid_id_start=args.grid_id_start,
        )

    process_folder(
        args.folder,
        args.api_key,
        args.url_signing_secret,
        args.style_map_id,
    )