View angle control in MATLAB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the view function do in MATLAB?

The view function sets or queries the viewing angle for 3D plots, controlling how the plot is seen from different directions.

beginner

How do you set the azimuth and elevation angles using view?

Use view(az, el) where az is the azimuth angle (rotation around vertical axis) and el is the elevation angle (height angle from horizontal plane).

intermediate

What is the default view angle in MATLAB 3D plots?

The default view angle is view(-37.5, 30), which means an azimuth of -37.5 degrees and elevation of 30 degrees.

beginner

How can you reset the view to 2D in MATLAB?

Use view(2) to set the view to a 2D view looking down the z-axis.

beginner

What happens if you use view(3) in MATLAB?

The command view(3) sets the view to the default 3D view with azimuth -37.5 and elevation 30 degrees.

Which command sets the view to look directly from above in MATLAB?

A view(0, 90)

B view(90, 0)

C view(2)

D view(3)

An elevation of 90 degrees means looking straight down from above, so view(0, 90) sets this view.

What does view(2) do in MATLAB?

A Zooms into the plot

B Sets a 3D default view

C Rotates the plot by 45 degrees

D Sets a 2D view looking down the z-axis

view(2) sets the view to 2D, looking down the z-axis.

How do you specify the azimuth and elevation angles in view?

A view(az, el)

B view(angle)

C view(x, y)

D view(azimuth)

The syntax view(az, el) sets azimuth and elevation angles.

What is the azimuth angle in view(az, el)?

A Angle from horizontal plane

B Zoom level

C Rotation around vertical axis

D Distance from origin

Azimuth is the rotation angle around the vertical axis.

Which command resets the view to MATLAB's default 3D angle?

A view(0, 0)

B view(3)

C view(2)

D view(90, 0)

view(3) resets the view to the default 3D angle.

Explain how to change the view angle of a 3D plot in MATLAB using the view function.

Think about how you turn your head left-right and up-down to look at something.

Describe the difference between view(2) and view(3) in MATLAB.

One looks from above, the other shows 3D perspective.

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