AstroPI - NCS_Orbit

Update: Our code achieved flight status and we are awaiting results!

This is the repository containing the scripts made by team NCS Orbit as part of the 2023 AstroPI Challenge. This year the challenge is to make a program that will calculate the velocity of the ISS.

This repository contains two main components: the submitted code for the competition named 'main.py' and the resources and past iterations of the code along with an exemplar script using image matching in the folder 'astropi-iss-speed-en-resources'

Our code uses is designed to capture images using a Raspberry Pi Camera, extract GPS coordinates and timestamps from the images, calculate the speed of the ISS (since the camera is on the ISS), and log the average speed to a text file. Here's a detailed explanation of the code:

Imports

• from PIL import Image: Used for image processing.
• from datetime import datetime, timedelta: For handling dates and times.
• import math: Provides mathematical functions.
• from picamera import PiCamera: Used to control the Raspberry Pi Camera.
• from time import sleep: For adding delays between operations.
• from pathlib import Path: For handling file system paths.
• import os: For interacting with the operating system, particularly the file system.

Function Definitions

1. capture_images(image_path, max_storage_size=250, max_images=42, max_capture_duration=480, capture_interval=5):

   • Captures images with the PiCamera until one of the limits is reached (storage size, number of images, or capture duration).
   • Parameters:
     • image_path: Directory where images are saved.
     • max_storage_size: Maximum storage size in MB.
     • max_images: Maximum number of images to capture.
     • max_capture_duration: Maximum duration for capturing images in seconds.
     • capture_interval: Time interval between captures in seconds.
   • Returns lists of captured image file paths and corresponding timestamps.

2. extract_coordinates_and_timestamp(image_path):

   • Extracts GPS coordinates and timestamps from the image's EXIF data.
   • Parameters:
     • image_path: Path to the image file.
   • Returns latitude, longitude, and timestamp if available, otherwise None.

3. haversine_distance(lat1, lon1, lat2, lon2):

   • Calculates the Haversine distance between two sets of latitude and longitude coordinates.
   • Parameters:
     • lat1, lon1: Latitude and longitude of the first point.
     • lat2, lon2: Latitude and longitude of the second point.
   • Returns the distance in kilometers.

4. calculate_speed(distance, time_difference):

   • Calculates speed given the distance and time difference.
   • Parameters:
     • distance: Distance between two points in kilometers.
     • time_difference: Time difference between two points as a timedelta object.
   • Returns speed in kilometers per second.

5. log_average_speed_to_txt(avg_speed, txt_file):

   • Logs the average speed to a text file.
   • Parameters:
     • avg_speed: Average speed in kilometers per second.
     • txt_file: Path to the text file.

Main Function

• main():
  • Sets paths for saving images and the result text file.
  • Calls capture_images to capture images and get their timestamps.
  • Extracts coordinates and timestamps from each pair of images.
  • Calculates the distance and speed between consecutive images.
  • Computes the average speed, applies an error correction, and logs it to the text file.
  • Deletes images if there are more than 42.

Execution

• if __name__ == "__main__": main(): Ensures the main function is called when the script is executed directly.

Usage

1. Capturing Images:

   • The capture_images function initializes the camera, captures images at specified intervals, and stores them in the specified directory.

2. Extracting Data:

   • The extract_coordinates_and_timestamp function reads each image's EXIF data to get GPS coordinates and the timestamp.

3. Calculating Distances and Speed:

   • The haversine_distance function calculates the distance between consecutive GPS coordinates.
   • The calculate_speed function computes the speed based on the distance and the time difference between captures.

4. Logging Average Speed:

   • The log_average_speed_to_txt function writes the calculated average speed to a text file.

5. Maintaining Image Count:

   • The script ensures that no more than 42 images are stored by deleting the oldest ones if necessary. This is to make sure that the limit of 250mb is satisfied.