Why am I unable to rotate an image object using the HGTRANSFORM function in MATLAB 7.0 (R14)?

I create an image in an hgtransform object. When I try to rotate the hgtransform object 90 degrees, I expect the image to rotate 90 degrees. Instead of rotating, the image is distorted as it translates across the axes. The following code reproduces the issue:

load clown

a = axes('XLim',[-150 150],'YLim',[-150 150]);

h = hgtransform('Parent',a);

colormap(map)

image('CData',X, ...

      'Parent',h, ...

      'XData',[0 100], ...

      'YData',[100 0]);

for r = 0:1:90

      T = makehgtform('zrotate',r*pi/180);

      set(h,'Matrix',T);

      pause(0.1);

      drawnow

end

Answer 1

[MathWorks Support Team]

This enhancement has been incorporated in Release 2006a (R2006a). For previous product releases, read below for any possible workarounds:

Documentation on the HGTRANSFORM function is missing the following information:

The object within the hgtransform needs to be a true 3-dimensional object for the rotation transform to produce the desired effect. The image is not a true 3-dimensional object. If a 3-dimensional transform is applied, the image is resized to fit a 2-dimensional projection of the hgtransform.

Only a true 3-dimensional object (i.e. a surface object) can be transformed correctly in a hgtransform object:

load clown

a = axes('XLim',[-150 150],'YLim',[-150 150]);

h = hgtransform('Parent',a);

colormap(map)

surface(ones(100),flipud(X),...

          'FaceColor','texturemap',...

          'EdgeColor','none',...

          'CDataMapping','direct',...

          'Parent', h)

for r = 0:1:90

      T = makehgtform('zrotate',r*pi/180);

      set(h,'Matrix',T);

      pause(0.1);

      drawnow

end