Adding Iso-Surfaces to Jim's 3-D Display

To add a rendered iso-surface to the 3-D display, select Load Iso-Surface ... from the File menu of the 3-D Viewer:

A dialog will now appear, from which you can select the image from which the iso-surface will be extracted and displayed.

First, select the image you want to work with by clicking on the icon, by typing in the folder (directory) and file name of the image, or by pressing the right mouse button and selecting from the menu of recently-used images.

This will automatically generate and display an iso-surface at an intensity level that is automatically selected. You can now make the following adjustments to change how the iso-surface is displayed.

• Iso-surface intensity threshold. This sets the intensity level at which the iso-surface is extracted.

  

  Move the slider to the left and right to set the iso-surface intensity to a different value. Please note that calculation of the iso-surface and redisplay normally takes several seconds after you adjust the threshold slider.

• Surface opacity. The surface opacity has a value between 0 (completely transparent) and 1 (completely opaque). Change the opacity using the opacity slider.

  

• Surface colour. The default colour with which the iso-surface is rendered is grey. To change the colour, click on the button and select the new colour from the colour chooser that will pop up.

• Surface shininess. The surface shininess has a value between 1 and 128. Change the shininess using the spinner.
• Render mode. The surface is defined by an array of linked triangles, and can be rendered as:
  • A solid surface. Select a render mode of "Fill".
  • A triangulated mesh. Select a render mode of "Wire frame".
  • A cloud of points. Select a render mode of "Points".
  The images below show the same 3-D iso-surface rendered in these three modes.

  An iso-surface rendered using the three modes.

  Fill	Wire frame	Points

• Surface fidelity. Setting the surface fidelity determines the number of triangles that will be calculated to define the surface - the greater the number of triangles, better will be the fidelity. However, the better the surface fidelity, the more time will be required to compute and display the surface. The images below show the same a 3-D dataset rendered with the three levels of fidelity.

  An iso-surface generated with three levels of fidelity.

  Low	Medium	High

  Using a low or medium surface fidelity setting causes the original dataset to be re-sampled to a lower spatial resolution so that the number of surface triangles is reduced. This has the effect of smoothing the iso-surface.

The effect of selecting the check-box is dealt with in the section about general controls.

If you click the button, the iso-surface will be removed from the 3-D viewer.