Specifying view matrix to use for 3D plot

Hello!

I am looking for a solution to the following problem. I can get the view matrix for some view of a 3D plot in Matlab using:

axis vis3d
M = view;

I would like to do the "inverse" of this code, i.e. specify a view matrix and set the view in the 3D plot to this matrix. How would I go about doing that? Unfortunately the view command takes view angles only and not a matrix, so it isn't as straightforward as view(M) and just the az/elev angle as parameters is an insufficient number of parameters. So how would one go about this best?

Thanks!

Answer 1

[Riya]

In MATLAB, the view command indeed takes azimuth and elevation angles as parameters, which is a simplified way of setting the camera view for a 3D plot. However, if you have a full view matrix, you can set the camera properties directly on the axes object to reconstruct the desired view.

The view matrix M that you get from MATLAB is a 4x4 transformation matrix that includes rotation and translation, which sets the camera's position and orientation in the scene. To apply this matrix to a 3D plot, you need to set the ‘CameraPosition’, ‘CameraTarget’, ‘CameraUpVector’, and ‘CameraViewAngle’ properties of the axes object.

% Assuming you have a 4x4 view matrix M 
% First, decompose the matrix to get the camera parameters 

% Camera position is the last column of the first three rows 
camPos = M(1:3, 4)'; 

% The camera target can be assumed at the origin (for simplicity) 
% since the view matrix handles the relative position of the camera 
camTarget = [0, 0, 0]; 

% The up vector is the second column of the first three rows 
camUpVec = M(1:3, 2)'; 

% Set the camera parameters to the current axes 
h = gca; % Get the handle to the current axes 
set(h, 'CameraPosition', camPos, ... 
    'CameraTarget', camTarget, ... 
    'CameraUpVector', camUpVec); 

% You might need to adjust the CameraViewAngle if necessary 
% set(h, 'CameraViewAngle', yourDesiredViewAngle); 

Please note that the actual camera target in your scene might not be the origin [0, 0, 0]. You may need to adjust ‘camTarget’ accordingly if you know the point that the camera should be looking at.

For more information you can refer following article:

https://www.mathworks.com/help/matlab/ref/gca.html