Color-based tracking in Drone Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the camera for color tracking.

Drone Programming

camera = DroneCamera([1]=True)

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

Athermal_vision

Bnight_mode

Ccolor_tracking

Dauto_focus

Attempts:

3 left

💡 Hint

Common Mistakes

Using night_mode instead of color_tracking disables color detection.

The camera must be set to color_tracking mode to detect colors for tracking.

2fill in blank

medium

Complete the code to set the target color for tracking.

Drone Programming

tracker.set_target_color([1])

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

A'blue'

B'red'

C'ultraviolet'

D'infrared'

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'infrared' or 'ultraviolet' which are not visible colors.

The target color must be a visible color like 'red' for the tracker to follow.

3fill in blank

hard

Fix the error in the code to correctly start the color tracking process.

Drone Programming

drone.[1]()

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

Astart_tracking

Bbegin_tracking

Cinitiate_follow

Dtrack_color

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'begin_tracking' or 'track_color' which are not valid methods.

The correct method to start tracking is start_tracking().

4fill in blank

hard

Fill both blanks to create a dictionary that maps detected colors to drone commands.

Drone Programming

commands = { [1]: 'move_left', [2]: 'move_right' }

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

A'red'

B'green'

C'blue'

D'yellow'

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping colors or using colors not in the options.

The dictionary maps 'red' to 'move_left' and 'blue' to 'move_right'.

5fill in blank

hard

Fill all three blanks to filter detected colors and execute commands only if confidence is high.

Drone Programming

if detected_color == [1] and confidence [2] [3]:
    execute_command(commands[detected_color])

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

A'red'

B>

C0.8

D'green'

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong color or comparison operator, or missing the confidence threshold.

The code checks if the detected color is 'red' and confidence is greater than 0.8 before executing the command.

Practice

1. What is the main purpose of color-based tracking in drone programming?

easy

A. To make the drone follow an object by detecting its color

B. To control the drone's altitude using GPS

C. To improve the drone's battery life

D. To send commands to the drone via remote control

Solution

1. Step 1: Understand color-based tracking concept

   Color-based tracking means the drone uses color detection to follow an object.

2. Step 2: Identify the main goal

   The goal is to detect and follow an object by its color, not altitude or battery.

3. Final Answer:

   To make the drone follow an object by detecting its color -> Option A

4. Quick Check:

   Color-based tracking = follow object by color [OK]

Hint: Focus on color detection as the tracking method [OK]

Common Mistakes:

• Confusing color tracking with GPS control
• Thinking it manages battery or remote commands
• Mixing color tracking with altitude control

2. Which of the following code snippets correctly initializes a color filter for red in a drone's tracking system?

easy

A. red_filter = {'lower': (0, 255, 255), 'upper': (10, 100, 100)}

B. red_filter = {'lower': [100, 0, 0], 'upper': [255, 10, 10]}

C. red_filter = {'low': (0, 100, 100), 'high': (10, 255, 255)}

D. red_filter = {'lower': (0, 100, 100), 'upper': (10, 255, 255)}

Solution

1. Step 1: Check correct keys for filter dictionary

   The keys should be 'lower' and 'upper' to define color range.

2. Step 2: Verify value types and ranges

   Values must be tuples with HSV ranges; red_filter = {'lower': (0, 100, 100), 'upper': (10, 255, 255)} uses correct keys and tuples.

3. Final Answer:

   red_filter = {'lower': (0, 100, 100), 'upper': (10, 255, 255)} -> Option D

4. Quick Check:

   Correct keys and tuple values = red_filter = {'lower': (0, 100, 100), 'upper': (10, 255, 255)} [OK]

Hint: Look for 'lower' and 'upper' keys with tuple HSV values [OK]

Common Mistakes:

• Using wrong dictionary keys like 'low' or 'high'
• Using lists instead of tuples for HSV values
• Swapping lower and upper HSV ranges

3. Given the following code snippet for detecting a blue object, what will be printed if the detected object's center is at (150, 200)?

blue_filter = {'lower': (100, 150, 0), 'upper': (140, 255, 255)}
object_center = (150, 200)
if 100 <= object_center[0] <= 140:
    print('Blue object detected at', object_center)
else:
    print('No blue object detected')

medium

A. Blue object detected at (150, 200)

B. SyntaxError

C. No blue object detected

D. RuntimeError

Solution

1. Step 1: Check the condition on x-coordinate

   Condition checks if 100 <= 150 <= 140, which is false because 150 > 140.

2. Step 2: Determine which print executes

   Since condition is false, else block runs printing 'No blue object detected'.

3. Final Answer:

   No blue object detected -> Option C

4. Quick Check:

   150 not in 100-140 range = No detection [OK]

Hint: Check numeric range conditions carefully [OK]

Common Mistakes:

• Assuming 150 is within 100 to 140 range
• Confusing syntax errors with logic errors
• Ignoring else block output

4. The following code is intended to detect a green object and print its position, but it raises an error. What is the error and how to fix it?

green_filter = {'lower': (40, 50, 50), 'upper': (80, 255, 255)}
object_center = None
if green_filter['lower'][0] <= object_center[0] <= green_filter['upper'][0]:
    print('Green object at', object_center)
else:
    print('No green object detected')

medium

A. SyntaxError due to incorrect dictionary keys; fix keys to 'low' and 'high'

B. TypeError because object_center is None; fix by assigning a tuple to object_center

C. IndexError because green_filter keys are missing; add keys

D. No error; code runs correctly

Solution

1. Step 1: Identify the error cause

   object_center is None, so accessing object_center[0] causes TypeError.

2. Step 2: Fix the error

   Assign a tuple like (x, y) to object_center before using it in condition.

3. Final Answer:

   TypeError because object_center is None; fix by assigning a tuple to object_center -> Option B

4. Quick Check:

   None used as index causes TypeError [OK]

Hint: Check variable types before indexing [OK]

Common Mistakes:

• Ignoring NoneType indexing error
• Changing dictionary keys incorrectly
• Assuming code runs without error

5. You want the drone to follow a yellow object but only if its detected center's y-coordinate is above 100. Which code snippet correctly implements this condition using color-based tracking?

yellow_filter = {'lower': (20, 100, 100), 'upper': (30, 255, 255)}
object_center = (120, 150)

# Choose the correct condition to check

hard

A. if yellow_filter['lower'][0] <= object_center[0] <= yellow_filter['upper'][0] and object_center[1] > 100:
print('Following yellow object')

B. if yellow_filter['lower'][1] <= object_center[1] <= yellow_filter['upper'][1] and object_center[0] > 100:
print('Following yellow object')

C. if yellow_filter['lower'][0] <= object_center[1] <= yellow_filter['upper'][0] and object_center[0] > 100:
print('Following yellow object')

D. if yellow_filter['lower'][1] <= object_center[0] <= yellow_filter['upper'][1] and object_center[1] > 100:
print('Following yellow object')

Solution

1. Step 1: Understand HSV and coordinate roles

   yellow_filter keys 'lower' and 'upper' define hue range at index 0; object_center[0] is x, object_center[1] is y.

2. Step 2: Check condition for hue and y-coordinate

   Hue check uses object_center[0] between lower and upper hue; y-coordinate must be > 100.

3. Final Answer:

   if yellow_filter['lower'][0] <= object_center[0] <= yellow_filter['upper'][0] and object_center[1] > 100: print('Following yellow object') -> Option A

4. Quick Check:

   Hue range on x and y > 100 condition = if yellow_filter['lower'][0] <= object_center[0] <= yellow_filter['upper'][0] and object_center[1] > 100: print('Following yellow object') [OK]

Hint: Match hue with x, check y > 100 separately [OK]

Common Mistakes:

• Mixing x and y coordinates in conditions
• Using wrong indices for hue or saturation
• Checking y-coordinate against hue range