Data Viewer v1.0

© Alexander Cech for VisLU 1999

Abstract:

Data Viewer is a Direct Volume Renderer - a program to visualize volumetric data sets, such as medical data like CT-scans.

Main Features:

Installation:

If you downloaded DataViewer from the Web, just execute the downloaded file.
If you have an installation floppy disk, execute setup.exe.
In both cases follow the instructions on screen.

Data sets:

To experiment with Data Viewer, you will also need a data set to view. You can download an example data set (a CT-scan of a human head) from http://www.cg.tuwien.ac.at/courses/Visualisierung/1999-2000/skewed_head.zip.

User interface:

General:

After opening a data set, you can manipulate the slice display by dragging the position indicator lines in the main display area. A specific density can be picked by right-clicking on a part of an image (needed for the Single isovalue surfaces classification method). Rendering parameters can be set in the menu Render/Edit parameters, and rendering is started with Render/Free and Render.

Menus

File / Open Dataset load a data set into memory
File / Load session parameters load settings
File / Save session parameters save all current settings (excluding the data set) to a file
File / Exit terminate Data Viewer
   
Options / Windowing displays the windowing window
Options / Transfer Functions displays the transfer functions window
Options / Live drag immediately update display when dragging slice-lines
Options / Show drag lines display slice drag lines
Options / Live Raycast display so far rendered image while rendering is in progress
   
Raycast / Edit parameters display the raycast parameters window
Raycast / .... some shortcuts to settings in the raycast parameter window
Raycast / Render renders the data set, using data cached from the previous rendering
Raycast / Free and Render renders the data set from scratch
Raycast / Free memory frees data cached from the previous rendering

Windowing

In the windowing window, drag the left and right boundaries to focus contrast to a specific area of interest.

Transfer function

Drag transfer function points with the left mouse button. Right-click to add or delete points, assign color or load/save the transfer function.

Raycast parameters

Here you define how the data set will be rendered.
View:
how the data set is rotated in space.
Shading model:
Color from Density: data density is directly mapped to a (grayscale) color
Color from Transfer function: color is assigned according to the defined transfer function
Classification model:
Opacity from Density: data density is directly mapped to opacity
Single Isovalue Surface: the closer data density is to the selected density, the more opacity it is assigned.
Multiple Isovalue Surfaces: opacity from the transfer function is applied to density boundaries.
Simple Transfer Function mapping: opacity from the transfer function is applied to each volume element.
Phong shading:
Simulates a light source illuminating the data set.
Image size:
Change scale to get a larger/smaller image.
Change samples/ray to get a more accurate image (= higher) or faster rendering (= lower).
Misc:
Use Trilinear Interpolation: data set values are trilinearly interpolated to give a more accurate image.
Cast rays from front to back: speeds up rendering (but is buggy in the current version!)
Swap gradient to/from disk: saves/loads gradient date to/from disk to avoid its permanent recalculation.

Sample Images
View 1

Rotation: X:90° Y:38° Z:0°
Shading: TF
Classification: Simple TF
Phong shading:
  20%, 80%, 0%, 0%
  Light: 1, -1, 0
  Exponent: 200
Trilinear Interpolation
View 1
View 2

Rotation: X:90° Y:38° Z:0°
Shading: TF
Classification: Simple TF
Phong shading:
  20%, 80%, 0%, 0%
  Light: 1, -1, 0
  Exponent: 200
Trilinear Interpolation
View 2
View 3

Rotation: X:0° Y:230° Z:0°
Shading: TF
Classification: Multiple Isov.
Phong shading:
  20%, 80%, 0%, 0%
  Light: 0, -1, 1
  Exponent: 200
Trilinear Interpolation
View 3
View 4

Rotation: X:103° Y:45° Z:0°
Shading: from Density
Classification: Single Isov.
Phong shading:
  20%, 80%, 0%, 0%
  Light: 0, -1, 1
  Exponent: 200
Trilinear Interpolation
View 4
View 5

Rotation: X:74° Y:302° Z:0°
Shading: TF
Classification: Simple TF
Phong shading:
  10%, 90%, 100%, 5%
  Light: -1, -1, 0.5
  Exponent: 100
Trilinear Interpolation
View 5