MATLAB: Rotate a 3D plot and keep it the same size

3d plotsgifMATLABrotationscaleview settings

I'm creating a GIF from a series of 3D plots, each one rotated from the previous by changing the viewpoint. Here is a snippet that does the frame generation:

for az=0:5:355
    view([az,el]);
    drawnow;
    frame = getframe(gcf);
    im = frame2im(frame);
    [imind,cm] = rgb2ind(im,256);
    imwrite(imind,cm,filename,'WriteMode','append','DelayTime',dt);
end

The problem I'm having is that each frame is magnified to fill the figure window, causing the plot to change size as it rotates. Here is a link to the GIF (it is also attached).

What view settings must I change to keep the 3D surface the same apparent size as I rotate it?

Best Answer

axis vis3d

Related Solutions

MATLAB: Setting Viewpoint with Azimuth, Elevation, and distance

Hi Viet, in order to control visualization in the current axes, consider these parameters also:

CameraPosition
CameraPositionMode
CameraTarget
CameraTargetMode
CameraUpVector
CameraUpVectorMode
CameraViewAngle
CameraViewAngleMode

and set them to your needs. You can get the full list of available parameters of the current axes by typing gca in the command line.

MATLAB: Does the view zoom in and out randomly when I try to rotate around the 3-D image

You must do two things in order to avoid seeing a "bouncing" affect as you rotate around a 3-D image.

1. Set 'CameraViewAngleMode' to 'Manual'

The 'CameraViewAngle' property determines the camera field of view. Changing this value affects the size of graphics objects displayed in the axes. By default, the 'CameraViewAngleMode' is set to 'Auto' so that MATLAB adjusts the view angle automatically. Setting 'CameraViewAngleMode' to 'Manual' prevents any unexpected adjustments. You can set this mode to manual with the following command:

set(axes_handle,'CameraViewAngleMode','Manual')

where "axes_handle" is the handle to axes (usually obtained by using the GCA command).

2. Setting the axes aspect ratio to 1.

Set the axes aspect ratio to [1 1] so that equal tick mark increments on the x-,y- and z-axis are equal in size. You can do this with the command:

axis equal

This step is very important in order to properly rotate around your image. As the camera moves through your coordinate system, it is important that each tick have equal value. If the tick marks in one direction are much larger than the tick marks in another direction, then the camera will appear to zoom in and out as it changes axis alignments.

The following code domonstrates how these two steps produce a smoothly rotating animation.

% This part of the code draws an arbitrary image
      figure('renderer','zbuffer','color','k')
      [x,y,z]=sphere;
      hold on
      for j=[-1 1],
          patch([-1 -1 1 1],[-1 1 1 -1],[j j j j],'b')
          patch([-1 -1 1 1],[j j j j],[-1 1 1 -1],'r')
          patch([j j j j],[-1 -1 1 1],[-1 1 1 -1],'g')
          surf(x+3*j,y,z)
          surf(x,y+3*j,z)
      end
      axis([-5 5 -6 6 -5 5],'off')
      view(3)
%%%%%%%%%%%%%%%%
% Get the current view angle
      [az,el]=view;
      el=el+15;
%%%%%%%%%%
% The next two lines prevent the "bouncing" affect as you rotate the camera
      set(gca,'cameraviewanglemode','manual')
      axis equal
% Now rotate around the image
      for j=10:10:360,
          view(az+j,el)
          pause(0.1)
      end

Best Answer

Related Solutions

MATLAB: Setting Viewpoint with Azimuth, Elevation, and distance

MATLAB: Does the view zoom in and out randomly when I try to rotate around the 3-D image

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