Black TIF images when filtering Landsat imagery in Google Earth Engine

I'm getting black TIF images with the following Python code: Changing the following parameters didn't help either:

center_point
width_meters
height_meters
height_from_ground
scale

import ee
import requests
from datetime import datetime
import zipfile
import io

ee.Authenticate() 

# Initialize Google Earth Engine
ee.Initialize()

def generate_rectangle(center_point, width_meters, height_meters, height_from_ground):
    """
    Generate a rectangle based on center point, width, height, and height from ground.
    """
    center_lon, center_lat = center_point
    half_width = width_meters / 2
    half_height = height_meters / 2

    # Convert the width and height from meters to degrees
    degrees_per_meter = 1 / 111000  # Approximate conversion
    half_width_deg = half_width * degrees_per_meter
    half_height_deg = half_height * degrees_per_meter

    # Create rectangle vertices
    top_left = (center_lon - half_width_deg, center_lat + half_height_deg)
    top_right = (center_lon + half_width_deg, center_lat + half_height_deg)
    bottom_left = (center_lon - half_width_deg, center_lat - half_height_deg)
    bottom_right = (center_lon + half_width_deg, center_lat - half_height_deg)

    # Create rectangle geometry
    rectangle = ee.Geometry.Polygon([top_left, top_right, bottom_right, bottom_left])

    # Buffer the rectangle by height_from_ground
    buffered_rectangle = rectangle.buffer(height_from_ground)

    return buffered_rectangle

def collect_data(center_point, width_meters, height_meters, height_from_ground, output_folder, num_images):
    """
    Collect satellite images and GPS locations within a specified rectangle.
    """
    # Generate rectangle geometry
    rectangle = generate_rectangle(center_point, width_meters, height_meters, height_from_ground)

    # Filter satellite imagery
    dataset = ee.ImageCollection('LANDSAT/LC08/C01/T1_SR') \
        .filterBounds(rectangle) \
        .filterDate('2015-01-01', '2020-12-31') \
        .sort('CLOUD_COVER') \
        .limit(num_images)

    # Iterate over images
    for i, image in enumerate(dataset.getInfo()['features']):
        # Get image ID
        image_id = image['id']
        print(f'Downloading image {i + 1}/{num_images}: {image_id}')

        # Get image metadata
        image_metadata = ee.Image(image_id).getInfo()

        # Get GPS coordinates
        coordinates = image_metadata['properties']['system:footprint']['coordinates']
        gps_coords = [(coord[1], coord[0]) for coord in coordinates]  # Fix here

        # Download image
        image_url = ee.Image(image_id).getDownloadURL({
            'scale': 250,  # Adjust scale as needed
            'crs': 'EPSG:4326',  # WGS84 coordinate system
            'region': gps_coords
        })

        # Save image
        timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")

        # Construct file name with timestamp
        filename = f"{timestamp}.zip"
        response = requests.get(image_url)

        if (response.status_code == 200):
            zip_file_bytes = io.BytesIO(response.content)
    
            # Create a ZipFile object from the file-like object
            with zipfile.ZipFile(zip_file_bytes, 'r') as zip_ref:
                # Extract all the contents to the specified folder
                zip_ref.extractall(timestamp + '\\')

                print("File downloaded successfully.")
        else:
            print("Failed to download file. Status code:", response.status_code)

# Example usage
center_point = (-122.084, 37.422)  # San Francisco coordinates
width_meters = 1000
height_meters = 1000
height_from_ground = 1000
output_folder = './/'
num_images = 1

# Collect data
collect_data(center_point, width_meters, height_meters, height_from_ground, output_folder, num_images)

The received file is a zip file, contains several black tif images I've been expected to get the appropriate GPS images Any help would be appreciated

Solution

The problem is located inside the next line of the collect_data function:

gps_coords = [(coord[1], coord[0]) for coord in coordinates]  # Fix here

You should put longitude first and then latitude in order to avoid GEE from constructing a polygon identical to ee.Geometry.Polygon, according to the function documentation.

ee.Geometry.Polygon(aLng, aLat, bLng, bLat, ..., aLng, aLat)

When coordinates are switched, the exported region fits the desired area, and the image is downloaded by bands correctly.

gps_coords = [(coord[0], coord[1]) for coord in coordinates]  # Fix here

The received file is a zip file, contains several black tif images I've been expected to get the appropriate GPS images.

These errors occur because the polygon created with (lat,lng) instead of (lng,lat) was located at the South Pole, a region very far away from the desired Landsat image.

An example of the B6 downloaded with the modified code.

I hope this response helps you.