Image stitching for mapping in Drone Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of image overlap calculation

What is the output of this code that calculates the overlap percentage between two drone images given their GPS coordinates and image width in meters?

Drone Programming

def calculate_overlap(coord1, coord2, image_width):
    distance = abs(coord2 - coord1)
    overlap = max(0, (image_width - distance) / image_width) * 100
    return round(overlap, 2)

print(calculate_overlap(100.0, 105.0, 10.0))

A 100.0

B 25.0

C 0.0

D 50.0

💡 Hint

Think about how much the images overlap if the distance between centers is less than the image width.

The distance between coordinates is 5 meters. The image width is 10 meters, so overlap is (10 - 5)/10 = 0.5 or 50%.

🧠 Conceptual

intermediate

Key step in image stitching

Which step is essential for stitching multiple drone images into a single map?

A Aligning images based on common features

B Increasing drone flight altitude

C Reducing image resolution

D Changing camera shutter speed

💡 Hint

Think about how images fit together like puzzle pieces.

Aligning images by matching common features ensures they overlap correctly to form a seamless map.

🔧 Debug

advanced

Identify the error in image stitching code

What error does this code raise when trying to stitch images using OpenCV's stitcher?

Drone Programming

import cv2
images = [cv2.imread('img1.jpg'), cv2.imread('img2.jpg')]
stitcher = cv2.Stitcher_create()
status, pano = stitcher.stitch(images)
print(status)

A AttributeError: module 'cv2' has no attribute 'Stitcher_create'

B TypeError: stitch() missing 1 required positional argument

C FileNotFoundError: img1.jpg not found

D No error, prints 0

💡 Hint

Check if the OpenCV version supports the Stitcher_create method.

In some OpenCV versions, Stitcher_create is not available or named differently, causing AttributeError.

📝 Syntax

advanced

Correct syntax for blending images

Which option correctly blends two images img1 and img2 with equal weights using OpenCV?

Drone Programming

import cv2
blended = ???
print(type(blended))

A cv2.add(img1 * 0.5, img2 * 0.5)

B cv2.addWeighted(img1, 0.5, img2, 0.5, 0)

C cv2.blend(img1, img2, 0.5)

D cv2.mixImages(img1, img2, 0.5)

💡 Hint

Look for the OpenCV function that mixes images with weights.

cv2.addWeighted blends two images with specified weights and a scalar added value.

🚀 Application

expert

Number of images needed for full map coverage

A drone camera covers 20 meters width per image. To map a 100m by 100m field with 30% overlap between images, how many images are needed along one side?

A 8

B 6

C 7

D 5

💡 Hint

Calculate effective coverage per image after overlap, then divide field length by that.

Effective coverage per image = 20m * (1 - 0.3) = 14m. Number of images = ceil(100 / 14) = 7.14 → 8 images.