View angle control in MATLAB - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of the view angle after this code?

Consider the following MATLAB code that sets the view angle of a 3D plot. What will be the azimuth and elevation angles after running this code?

MATLAB

figure;
plot3(1:10, rand(1,10), rand(1,10));
view(45, 30);
current_view = view;

A [45 30]

B [30 45]

C [0 90]

D [90 0]

💡 Hint

The view function in MATLAB takes azimuth first, then elevation.

The view function sets the azimuth and elevation angles in that order. So view(45,30) sets azimuth to 45 degrees and elevation to 30 degrees.

❓ Predict Output

intermediate

What happens if you call view with a single argument?

What is the effect of calling view(2) in MATLAB on a 3D plot?

MATLAB

figure;
plot3(1:10, rand(1,10), rand(1,10));
view(2);
current_view = view;

A [2 0]

B [0 90]

C [90 0]

D [45 30]

💡 Hint

Calling view with a single number sets a predefined view.

In MATLAB, view(2) sets the view to the top view of the XY plane, which corresponds to azimuth 0 and elevation 90.

❓ Predict Output

advanced

What is the output of this code changing view angles dynamically?

What will be the final azimuth and elevation angles after running this MATLAB code?

MATLAB

figure;
plot3(1:10, rand(1,10), rand(1,10));
for az = 0:45:180
    view(az, 45);
end
final_view = view;

A [0 45]

B [135 45]

C [45 45]

D [180 45]

💡 Hint

The loop sets the view multiple times, the last one is the final.

The loop increments azimuth from 0 to 180 in steps of 45, setting elevation to 45 each time. The final call is view(180,45).

❓ Predict Output

advanced

What error does this code raise?

What error will this MATLAB code produce?

MATLAB

figure;
plot3(1:10, rand(1,10), rand(1,10));
view('top');

A Error: Invalid input argument for view

B Error: Too many input arguments

C Error: Undefined function or variable 'top'

D No error, sets view to top

💡 Hint

The view function expects numeric inputs or specific strings like '2D' or '3D'.

The string 'top' is not a valid input for view in MATLAB, so it raises an invalid input argument error.

🧠 Conceptual

expert

How to programmatically rotate a 3D plot by 90 degrees around the vertical axis?

Which MATLAB code snippet correctly rotates an existing 3D plot by 90 degrees around the vertical (z) axis from its current view?

A view(0, 90);

B view(90, 0);

C

current_view = view;
view(current_view(1) + 90, current_view(2));

D view(current_view(1), current_view(2) + 90);

💡 Hint

Azimuth controls rotation around the vertical axis.

Adding 90 degrees to the azimuth angle rotates the plot 90 degrees around the vertical axis while keeping elevation unchanged.

Practice

1. What does the MATLAB command view(45, 30) do in a 3D plot?

easy

A. Changes the plot colors based on angles 45 and 30

B. Rotates the plot by 45 degrees around the z-axis only

C. Sets the viewpoint to 45 degrees azimuth and 30 degrees elevation

D. Zooms into the plot by a factor of 45 and tilts by 30 degrees

Solution

1. Step 1: Understand the view function parameters

   The view function takes two angles: azimuth (horizontal rotation) and elevation (vertical rotation).

2. Step 2: Interpret the given angles

   Here, azimuth is 45 degrees and elevation is 30 degrees, setting the viewpoint accordingly.

3. Final Answer:

   Sets the viewpoint to 45 degrees azimuth and 30 degrees elevation -> Option C

4. Quick Check:

   view(az, el) sets angles = D [OK]

Hint: Remember view(az, el) sets horizontal and vertical angles [OK]

Common Mistakes:

• Confusing azimuth with elevation
• Thinking view rotates plot instead of viewpoint
• Assuming view changes colors or zoom

2. Which of the following is the correct syntax to set the view angle to azimuth 90 and elevation 0 in MATLAB?

easy

A. view(90, 0);

B. view(90 0);

C. view(az=90, el=0);

D. view(azimuth=90, elevation=0);

Solution

1. Step 1: Recall MATLAB view function syntax

   The correct syntax is view(az, el) where az and el are numeric values.

2. Step 2: Check each option

   Only view(90, 0); matches the correct syntax. The others either omit the comma between arguments or use named parameters not supported by MATLAB's view function.

3. Final Answer:

   view(90, 0); -> Option A

4. Quick Check:

   Correct syntax is view(az, el) [OK]

Hint: Use view(az, el) with two comma-separated numbers, no named parameters [OK]

Common Mistakes:

• Omitting comma between arguments
• Trying to name parameters like az= or azimuth=
• Passing a vector instead of two separate arguments

3. What will be the effect of the following MATLAB code on a 3D plot?

surf(peaks);
view(0, 90);

medium

A. View from the front, showing the plot's height

B. View from directly above, looking down on the plot

C. View from the side, showing the plot's depth

D. View rotated 90 degrees around the x-axis

Solution

1. Step 1: Understand the view angles

   Azimuth 0 means looking along the x-axis, elevation 90 means looking straight down from above.

2. Step 2: Apply to the 3D plot

   Setting view(0, 90) shows the plot from directly above, flattening depth perception.

3. Final Answer:

   View from directly above, looking down on the plot -> Option B

4. Quick Check:

   view(0, 90) = top-down view [OK]

Hint: Elevation 90 means looking straight down [OK]

Common Mistakes:

• Thinking azimuth 0 means side view
• Confusing elevation 90 with front view
• Assuming rotation around x-axis changes view

4. Identify the error in this MATLAB code snippet for setting a 3D plot view:

plot3(x, y, z);
view(45 30);

medium

A. Missing comma between the two arguments in view

B. Missing semicolon after plot3 command

C. plot3 cannot be used with view function

D. Angles 45 and 30 are out of valid range

Solution

1. Step 1: Check the view function usage

   The view function requires two separate arguments separated by comma.

2. Step 2: Analyze the code snippet

   Using view(45 30) passes two numbers without comma separator, causing a syntax error.

3. Final Answer:

   Missing comma between the two arguments in view -> Option A

4. Quick Check:

   view needs two comma-separated numbers [OK]

Hint: Pass angles as two comma-separated numbers [OK]

Common Mistakes:

• Thinking semicolon omission causes error here
• Believing plot3 and view are incompatible
• Assuming angle values are invalid

5. You want to create a MATLAB script that shows a 3D surface plot of peaks and then rotates the view smoothly from azimuth 0 to 360 degrees at elevation 30 degrees. Which code snippet correctly achieves this?

hard

A. surf(peaks);
view(0, 30);
for az = 0:10:360
pause(0.1);
view(az, 30);
end

B. for az = 0:10:360
surf(peaks);
view(az, 30);
pause(0.1);
end

C. for az = 0:10:360
view(az, 30);
surf(peaks);
pause(0.1);
end

D. surf(peaks);
for az = 0:10:360
view(az, 30);
pause(0.1);
end

Solution

1. Step 1: Plot surface once before loop

   Plotting surf(peaks) once before the loop avoids redrawing the plot repeatedly, improving performance.

2. Step 2: Update view inside loop with pause

   Loop changes azimuth from 0 to 360, updating view angle smoothly with pause(0.1) to see animation.

3. Final Answer:

   surf(peaks); for az = 0:10:360 view(az, 30); pause(0.1); end -> Option D

4. Quick Check:

   Plot once, then loop view update = A [OK]

Hint: Plot once, then loop view changes with pause [OK]

Common Mistakes:

• Plotting inside the loop causing flicker
• Calling view before surf plot exists
• Not pausing to see the rotation effect