Doug’s MATLAB Video Tutorials

November 17th, 2009

I like his slow, clear, methodical presentation with great visualizations. It is the first time I have deeply understood some of the volume visualization techniques we have.

• 1 of 9 Definitions for scalar and vector fields.
• 2 of 9 Examples of scalar and vector fields (temperature in a room vs air currents)
• 3 of 9 Displays scatter3 and slice plots.
• 4 of 9 Displays contourslice and isosurface.
• 5 of 9 Making a 3-d plot ‘pretty’ with lighting, shading, interpolation, etc…
• 6 of 9 Displays quiver3 and coneplot
• 7 of 9 Displays and explains streamplot and streamslice
• 8 of 9 Displays and explains streamtubes and streamribbons
• 9 of 9 Unifying example

16:40 UTC | Posted in Format: Video, Level: Basic | Permalink |

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2 Responses to “Basics: Volume visualization: 5/9 Making a 3-d plot ‘pretty’ with lighting, shading, interpolation, etc…”

1. Tom Clark replied on November 18th, 2009 at 11:24 UTC :
   

   Nice, thanks to Doug and Patrick.

   The alpha command is useful - I hadn’t come across that, and always struggled with setting facealpha value etc for individual patches.

   Also well worth a mention is the isonormals command, which effectively removes the faceted appearance of the patch objects (although gouraud lighting helps, computing the isonormals is still a substantial improvement).

   From the ML isonormals help:

   data = cat(3, [0 .2 0; 0 .3 0; 0 0 0], ...
                 [.1 .2 0; 0 1 0; .2 .7 0],...
                 [0 .4 .2; .2 .4 0;.1 .1 0]);
   data = interp3(data,3,'cubic');
   
   subplot(1,2,1)
   p1 = patch(isosurface(data,.5),...
   'FaceColor','red','EdgeColor','none');
   view(3); daspect([1,1,1]); axis tight
   camlight; camlight(-80,-10); lighting phong;
   title('Triangle Normals')
   
   subplot(1,2,2)
   p2 = patch(isosurface(data,.5),...
       'FaceColor','red','EdgeColor','none');
   isonormals(data,p2)
   view(3); daspect([1 1 1]); axis tight
   camlight;  camlight(-80,-10); lighting phong;
   title('Data Normals')
   

2. Patrick Kalita replied on November 18th, 2009 at 13:58 UTC :
   

   Hello! This is Patrick, that voice you hear in this video.

   As Tom notes, the ISONORMALS command is great to use in conjunction with the ISOSUFACE command. ISONORMALS can make the surface look more continuous by adjusting the ‘VertexNormals’ property of the patch object based on the gradient of the underlying data. In fact, when you call ISOSURFACE without an output argument it makes use of the ISONORMALS command.

   In the interest of limiting the total length of this presentation to one hour I had to forgo talking about the nice ISOSURFACE-helpers like ISONORMALS, ISOCAPS, and ISOCOLORS. But please feel free to check them out in the documentation:
   http://www.mathworks.com/access/helpdesk/help/techdoc/ref/isonormals.html
   http://www.mathworks.com/access/helpdesk/help/techdoc/ref/isocaps.html
   http://www.mathworks.com/access/helpdesk/help/techdoc/ref/isocolors.html

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a = magic(3);
sum(a)
</pre>

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