Image stitching for mapping in Drone Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to load images for stitching.

Drone Programming

images = [cv2.imread([1]) for file in image_files]

Drag options to blanks, or click blank then click option'

Acv2

Bimages

Cimage_files

Dfile

Attempts:

3 left

💡 Hint

Common Mistakes

Using the list name instead of the loop variable.

Using the wrong variable name that does not hold filenames.

The variable file holds each filename in the list image_files. We use it to load each image with cv2.imread().

2fill in blank

medium

Complete the code to initialize the stitcher object.

Drone Programming

stitcher = cv2.Stitcher_create([1])

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Acv2.STITCHER_PANORAMA

Bcv2.IMREAD_COLOR

Ccv2.INTER_LINEAR

Dcv2.COLOR_BGR2GRAY

Attempts:

3 left

💡 Hint

Common Mistakes

Using image reading or color conversion constants instead of stitcher mode.

Passing no argument or wrong argument type.

cv2.STITCHER_PANORAMA tells the stitcher to create a panorama from images.

3fill in blank

hard

Fix the error in the code to stitch images correctly.

Drone Programming

status, stitched = stitcher.[1](images)

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Amerge

Bstitch

Ccombine

Dblend

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect method names like 'combine' or 'merge'.

Trying to call a non-existent method.

The correct method to stitch images in OpenCV is stitch().

4fill in blank

hard

Fill both blanks to check if stitching was successful and save the result.

Drone Programming

if status == [1]:
    cv2.[2]('stitched_output.jpg', stitched)

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Acv2.imwrite

B0

C1

Dcv2.imwriteAsync

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing status codes for success.

Using asynchronous save function which is not standard.

In OpenCV stitching, 0 (cv2.Stitcher_OK) means success. We use cv2.imwrite to save the image.

5fill in blank

hard

Fill all three blanks to create a dictionary of image sizes for mapping.

Drone Programming

image_sizes = [1]((file, (img.shape[[2]], img.shape[[3]])) for file, img in zip(image_files, images))

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Adict

B0

C1

Dlen

Attempts:

3 left

💡 Hint

Common Mistakes

Using list or set instead of dict.

Mixing up height and width indices.

We use dict to create a dictionary. img.shape[0] is height and img.shape[1] is width of the image.

Practice

1. What is the main purpose of image stitching in drone programming?

easy

A. To combine multiple drone photos into one large map

B. To control the drone's flight path

C. To improve the drone's battery life

D. To send live video feed to the operator

Solution

1. Step 1: Understand image stitching concept

   Image stitching is about joining many photos to create a bigger picture.

2. Step 2: Identify the main use in drone programming

   It helps create large maps from many drone images for better area coverage.

3. Final Answer:

   To combine multiple drone photos into one large map -> Option A

4. Quick Check:

   Image stitching = combine photos [OK]

Hint: Image stitching means joining photos into one big map [OK]

Common Mistakes:

• Confusing image stitching with drone control
• Thinking it improves battery life
• Mixing it with live video streaming

2. Which of the following is the correct way to start stitching images side by side in a drone program?

easy

A. stitch(images, method='side_by_side')

B. stitch(images, method='fly_path')

C. stitch(images, method='battery_save')

D. stitch(images, method='live_feed')

Solution

1. Step 1: Identify stitching method names

   Side by side stitching joins images horizontally or vertically.

2. Step 2: Match method to stitching task

   Only 'side_by_side' matches the stitching method; others relate to flight or battery.

3. Final Answer:

   stitch(images, method='side_by_side') -> Option A

4. Quick Check:

   Method 'side_by_side' = stitching images side by side [OK]

Hint: Use method='side_by_side' to join images simply [OK]

Common Mistakes:

• Using unrelated methods like 'fly_path' or 'battery_save'
• Confusing stitching method with drone flight commands
• Misspelling method names

3. Given the code snippet:

images = ['img1.jpg', 'img2.jpg', 'img3.jpg']
stitched_map = stitch(images, method='overlap')
print(len(stitched_map))

What will be the output if stitched_map is a combined image with 3 parts?

medium

A. 1

B. 3

C. 0

D. Error

Solution

1. Step 1: Understand the stitch function output

   Stitching combines images into one big image, so the result is a single image object.

2. Step 2: Check what len() returns on the stitched image

   Most image objects do not support len(), so calling len() will cause an error.

3. Final Answer:

   Error -> Option D

4. Quick Check:

   len() on image object causes error [OK]

Hint: len() on stitched image causes error [OK]

Common Mistakes:

• Assuming length equals number of input images
• Expecting len() to work on image object
• Confusing list length with image object length

4. The following code is meant to stitch images with overlap detection but throws an error:

images = ['a.jpg', 'b.jpg']
stitched = stitch(images, method='overlap')
stitched.show()

What is the likely cause of the error?

medium

A. The method 'overlap' is not supported

B. The show() method does not exist for stitched images

C. The stitch function requires images to be loaded, not file names

D. The images list is empty

Solution

1. Step 1: Check input type for stitch function

   Stitch usually needs image data, not just file names as strings.

2. Step 2: Identify error cause

   Passing file names without loading images causes errors when stitching or showing.

3. Final Answer:

   The stitch function requires images to be loaded, not file names -> Option C

4. Quick Check:

   Input must be loaded images, not file names [OK]

Hint: Load images before stitching, not just file names [OK]

Common Mistakes:

• Assuming method 'overlap' is invalid
• Thinking show() method is missing
• Ignoring that images list is not empty

5. You want to create a stitched map from drone images but only include images that have at least 30% overlap with the previous one. Which approach best applies this condition in your stitching code?

hard

A. Stitch all images first, then crop the map to overlapping areas

B. Filter images by overlap percentage before stitching using a function

C. Use method='side_by_side' to ignore overlap

D. Manually stitch images without any overlap checks

Solution

1. Step 1: Understand the overlap condition

   Only images with at least 30% overlap should be included in stitching.

2. Step 2: Choose the best way to apply this condition

   Filtering images before stitching ensures only suitable images are combined.

3. Final Answer:

   Filter images by overlap percentage before stitching using a function -> Option B

4. Quick Check:

   Filter first, then stitch = correct approach [OK]

Hint: Filter images by overlap before stitching [OK]

Common Mistakes:

• Stitching all images then cropping
• Ignoring overlap and stitching side by side
• Manual stitching without overlap checks