Programmer Documentation

What is the 3D-Texture Based Volume Rendering?

Direct volume rendering has become an invaluable visualization technique for a wide variety of applications. Our 3D texture-based volume rendering software runs on commodity PC clusters. The software exploits the hardware accelerated 3D texture mapping that is available on commodity graphics processors today.

What is the Parallel Volume Rendering Server?

The Parallel Volume Rendering server is a parallel multi-PC volume rendering system using off-the-shelf commodity components. This Volume Rendering server provides the combined geometry and volume rendering.

The parallel volume rendering server runs in two modes:

1. A single tile display – generates 1280x1024 Image or less and sends the image to client.

2. Multi-tiled display – generates a very large tiled immersive image and displays the image with display servers.

What is the Parallel Multi-tiled Display Paralleled Volume Rendering?

The Parallel Multi-tiled Display Paralleled Volume Rendering is an application of very large tiled immersive displays with Volume data. This application is to display the Rendered Image with high resolution.

Requirements

The following are the requirements for hardware and installing the Volume Rendering Server.

Hardware:

An NVIDIA GeForce3 card or greater for each Computer

Software:

Glut library

MPI library

CORBA library

The following are the requirements for hardware and installing the display Server.

Hardware:

An NVIDIA GeForce2 card or greater for each Computer

Software:

Glut library

CORBA library

Installation

The latest detailed installation instructions can be found in a file called README in the 3D Based Volume Rendering distribution.

Inputs to the Volume Rendering Server

The 3D Based Volume Rendering server currently accepts CCV’s raw(without header), rawiv(with header), slice and rawV(with variables) file types.

Raw

Rawiv

Slice

RawV

Creating DataInfo.txt

Each Sub-node reads this DataInfo.txt file and loads the indicated dataset.

# is used as a comment.

Write information with the following order.

dataset name i.e) vhmale_128*128*128

data type with format i.e) RAWIVUC, RAWUS, RAWSLICEUS

data full path

dimX dimY dimZ - number of vertices of in X Y Z direction resplectively

StartFileNum NumOfFile - start file number number of file

FileExtension - i.e) fre for Slice format, NULL for others

Min Max - minimum value maximum value

ratioX ratioY ratioZ

A Description of Ipaq Client interface

The client is associated with a Compaq iPAQ Pocket PC. The Client receives information such as the location, the Zoom of Object, rotation Matrix, and transfer function from wireless controller. The client sends all information to Rendering Server.

1. Top 10 white boxes indicate each projector and the longhorn symbol object position.

Change the position of object is done by pointing anywhere within 10 white boxes or pointing the longhorn symbol and drag around.

2. The center cube represents the object.

Changing the Rotation Matrix is done by rotating the cube.

3. The right green color rectangle is for changing Zoom.

Changing the Zoom is done by pointing and dragging up for Zoom in and down for Zoom out.

Editing the Transfer Function with Ipaq (wireless controller)

The volume rendering transfer function assigns colors and opacities to different densities in the dataset. In Some sense your visualization is only as good as your transfer function. Becoming proficient with the Volume Rover’s Colormap Editor will serve you well.

Opacity Function

Changing the opacity function is done by moving Alpha Nodes around. To move an Alpha Node, point the pen on the node and drag. To add more Alpha Nodes to your opacity function, point the pen and hold on the colormap editor to bring up the small menu shown in the figure of the Colormap Editor. Then point on Add -> Alpha Node. Adding more Alpha Nodes gives your greater control over the shape of the opacity function.

Colors

The color spectrum of the Colormap Editor can be changed by editing, adding and moving color nodes.

Editing To change the color of an existing color node, point and hold on the color node to display the Colormap Editor menu. Click Edit to bring up a standard color selection dialog.

Adding To add a color node, bring up the Colormap Editor Menu and select Add -> Colornode. You can change the color of the node by following the procedure for editing.

Moving Color nodes can be moved left and right along the Colormap Editor by left clicking and dragging.

Transfer Function Files

For a particular dataset, arriving at a good transfer function is a trial and error process. It is the most time consuming part of using the iPAQ control. Therefore, the Colormap Editor’s settings can be saved and loaded up later.

Point and hold on the Colormap Editor to bring up the menu and click on save.

The suffix for transfer function files is *.vinay. Transfer function files must be called *.vinay.