vistit the homepage Vienna University of TechnologyTECHNISCHE UNIVERSITÄT WIEN
Institut für Computergraphik und Algorithmen
Abteilung für Computergraphik


Overview

Introduction

VolRendering is a tool to visualize CT and MRT scans. Orthographic views from front, top and side as well as perspective views on the dataset are available. It is based on the paper Display of Surfaces from Volume Data from Marc Levoy [1].

Screenshots

Graphical User Interface

The main window is split up into four view sections,a control panel and a main menu.

Main Menu

File

  • Open: Opens a volumetric dataset

  • Save Image: Saves an image of the perspective view. Width and height of the image must be entered.

  • Exit: Closes the program.

Transfer Function

  • New Transfer Function: The currently active transfer function is cleared

  • Load Transfer Function: Loads a previously saved transfer function. The active transfer function is overwritten.

  • Edit Transfer Function: Opens the ->transfer function editor

  • Save Transfer Function: Saves the active transfer function into a file.

View Section




The four view sections are:

  1. Top View

  2. Front View

  3. Side View

  4. Perspective View

Double-Clicking with the left mouse button on a viewport maximizes it. Double-Clicking again with the left mouse button restores the original view.

The object in the perspective view can be rotated by clicking with the left mouse button in the perspective window and moving the mouse while the mouse button is pressed. Pressing the right mouse button and moving with the mouse zooms the object.

Control Panel




The control panel shows the currently used transfer function (1 and 2) and parameters for 2D (orthographic) and 3D (perspective) view.

2D (Orthographic)


  • Use Transferfunction: The active transfer function is also used for the orthographic view. Only the color part of the transferfunction is used. Opacity has no influence on the orthographic view.

  • Front, Side, Top: These sliders are used to slice through the orthographic views.

3D (Perspective)


  • Use Shading: Activate Gouraud shading for the perspective view.

  • Use Shadows: Shadows on the object are displayed

  • Steps: Number of raymarching steps through the object

  • Shadow Steps: Number of raymarching steps for shadow calculation


Transfer Function Editor




  1. Opacity Editor: Edit window for the opacity values of a transfer function

  2. Color Editor: Edit window for the color gradient values of a transfer function.

  3. Zoom: Horizontal and vertical zoom of the transfer function.

Using the Editor

Double Clicking with the left mouse button adds a new opacity or color point. Use drag & drop with the left mouse button on a point to move it around. Clicking on a point with the right mouse button deletes it. Double-Click on a color point opens the color dialog and a new color can be selected for that point. The first and the last point are fixed and cannot be moved or deleted, except the opacity value for the first and last point can be set.

References

[1] Marc Levoy, "Display of Surfaces from Volume Data", IEEE Computer Graphics and Applications, Vol. 8(3), pp. 29-37, Feb.1987