To do these exercises you must run DX and the scalar field program. When the image window appears, click on the Windows menu of the Image window and select the Open VIsual Program Editor (VPE) item. The program source should appear.

Remember that you can get help in DX on any module by selecting the "context sensitive help" item from the help menu, then clicking the left mouse button on a module.

• Volume Rendering.
  Volume rendering attempts to show a scalar field as light sources or densities with a color proportional to the scalar value at each point. The alogrithm does not try to construct any surfaces, but rather computes a light distribution from each volume element. This is sometimes refered to as the "colored jello" technique for scalar fields. To volume render:
  1. Remove modules in the left branch of the program (isosurface, showbox, selector, clipplane, switch), but leave the color and colormap modules.
  2. Connect the first input of the color module to the output of the Import module.
  3. Add an Options module by:
     1. Clicking on the Structuring Catagory at the upper-left side of the VPE.
     2. Clicking on the Options item of the list in the lower-left side of the VPE.
     3. Clicking to the left side of the Collect module to place the new Options module.
  4. Connect the output of the color module to the options module.
  5. Connect the output of the options module to the collect module.
  6. Double-click the options module and enter the string "color multiplier" in the first attribute field. Enter the number 0.05 in the first value field. The color multiplier sets the intensity range of the the volume rendering.
  7. Modify the color map as shown. The data range should be set to 0.05 to 2.0.
  8. Execute the program by selecting the Execute Once item from the Execute menu.

  The program should now look like this, (with the options dialog box open) and will generate a volume image.

• Add a box around the scene.
  1. Add an input tab to the Collect module by selecting it with a mouse click, then typing control-A.
  2. Add a Tube module by:
     1. Clicking on the Annotation Catagory at the upper-left side of the VPE.
     2. Clicking on the Tube item of the list in the lower-left side of the VPE.
     3. Clicking to the right side of the Collect module to place the new Tube module.
  3. Connect the output tab of the Tube module to the new input of the Collect.
  4. Connect the first output of the ShowBox module to the input of the Tube module.
  5. Execute the program by selecting the Execute Once item from the Execute menu.

  The program should now look like this, and will generate an image with a bounding box.

• Put a text value next to each contour.
  1. Add an input tab to the Collect module by selecting it with a mouse click, then typing control-A.
  2. Add a Sample module by:
     1. Clicking on the Realization Catagory at the upper-left side of the VPE.
     2. Clicking on the Sample item of the list in the lower-left side of the VPE.
     3. Clicking to the right side of the Collect module to place the new Sample module.
     4. Double-click the Sample module and enter a 1 in the "density" field of the dialog box. This causes the Sample module to creat just one location on each existing coutour line.
  3. Add a Autoglyph module by:
     1. Clicking on the Annotation Catagory at the upper-left side of the VPE.
     2. Clicking on the Autoglyph item of the list in the lower-left side of the VPE.
     3. Clicking to the right side of the Collect module to place the new Autoglyph module.
     4. Double-click the Autoglyph module and enter "text" in the "type" field of the dialog box.
  4. Connect the output tab of the Autoglyph module to the new input of the Collect.
  5. Connect the output of the Sample module to the input of the Autoglyph module.
  6. Connect the output of the right-most isosurface module to the input of the Sample module.
  7. Execute the program by selecting the Execute Once item from the Execute menu.

  The program should now look like this, and will generate an image with values attached to each contour line.

• Add a Colorbar.
  1. Add an input tab to the Collect module by selecting it with a mouse click, then typing control-A.
  2. Add a ColorBar module by:
     1. Clicking on the Annotation Catagory at the upper-left side of the VPE.
     2. Clicking on the colorbar item of the list in the lower-left side of the VPE.
     3. Clicking to the right side of the Collect module to place the new colorbar module.
  3. Connect the output tab of the colorbar module to the new input of the Collect.
  4. Connect the first output of the colormap module to the input of the colorbar module.
  5. Execute the program by selecting the Execute Once item from the Execute menu.

  The program should now look like this, and will generate an image with a color bar which relates data values to colors. The ColorBar module has many options which may be set, including orientation, font size, number of tick marks and data min/max.

• Reduce the field.
  Sometimes you may want to reduce the data size of a field for faster rendering or to save memory, or, occasionally, to smooth out very noisy data. The Reduce module will average together groups of data values to produce a lower resolution field. To reduce the field:
  1. Disconnect the Import module output from the left-most isosurface module and the MaptoPlane module.
  2. Add a Reduce module by:
     1. Clicking on the Imprt/Export Catagory at the upper-left side of the VPE.
     2. Clicking on the Reduce item of the list in the lower-left side of the VPE.
     3. Clicking to the under the Import module to place the new Reduce module.
  3. Connect the output tab of the Reduce module to the input of the isosurface and MaptoPlane modules.
  4. Connect the output of the Import module to the first input of the Reduce module.
  5. Execute the program by selecting the Execute Once item from the Execute menu.

  The program should now look like this, and will generate an image based on a lower resolution field. The contour lines look jaggie because of the lower resolution.

• Data Readout using a probe.
  DX supports direct interaction with an object in the image window via an module called a "probe". This exercise is somewhat more complicated than the last few, so the implementation description will be compressed.
  1. Add an input to the existing collect module.
  2. Add the following modules (refer to the program for module placement):
     1. A Probe module from the Special catagory.
     2. A Construct module from the Realization catagory. Enter a 1.0 in the data field of the Construct dialog box. This will build a one-point field structure.
     3. Two Autoglyph modules from the Annotation catagory. Set the scale field of one dialog box to 0.5 (for the Autoglyph which is highlighted in the image above). For the Autogylph module connected to the Map module, set the type field to "text" .
     4. A Map module from the Transformation catagory. The map module interpolates the 3D scalar field onto the the new field created by the Construct module.
     5. A Color module from the Transformation catagory. Set the "color" field in the module dialog box to "white".
     6. A Collect module from the Structuring catagory.
  3. Connect the modules as shown in the link above.
  4. Select the Viewcontrol item from the Options menu in the image window. On the Viewcontrol pop-up set the mode to "cursors".
  5. In the image window a box will appear. Double-click anywhere in the box to creat the new probe location. Once created, the probe may be dragged with the mouse. You can only drag parallel to the projection of the principle axes .
  6. Execute the program by selecting the Execute Once item from the Execute menu.

  The program should now look like this, and will generate an image with a marker (glyph) for the measurement location and the field value in text form.

• Show Isosurface Connections.
  Sometimes a set of nested isosurfaces is hard to understand. A given surface may be highlighted using this technique. Again, the implementation description will be compressed.
  1. Add the following modules (refer to the program for module placement):
     1. A Integer module from the Interactor catagory. While the Integer module is still highlighted, bring the control panel window up and choose the "add selected interactor" item from the Edit menu, then click in the control panel to drop the Integer widget. Double-click the widget and set the range to 0 to 3 in the dialog box. (Since there are just four isosurfaces in this example.)
     2. A Select module from the Structuring catagory. Since the isosurface module generates a group of fields, one field per value, the select module can pick one member of the group.
     3. A ShowConnections module from the Realization catagory. This converts an object from polygonal form to a wireframe.
     4. A Collect module from the Structuring catagory.
  2. Connect the modules as shown in the program link above.
  3. Use the new integer widget to set a value between 0 and 3 to highlight a single isosurface.
  4. Execute the program by selecting the Execute Once item from the Execute menu.

  The program should now look like this, and will generate an image with a triangle grid in the selected isosurface (in this case, the integer widget was set to 2 to highlight the green level.)