Powerwall

Powerwall Display

An Introduction

Powerwall is a 3D immersive display used for projecting computer generated images with high resolution. Powerwall has variety of sizes and shapes for different tracking environments. The powerwall is designed according to the intended applications. Its main applications are interacting with the 3D models and act as a presentation tool for several applications. It displays large volumetric data sets such as analyzing election results which helps to analyze the data easily. By using the powerwall, multiple images can be viewed at the same time.

Need for Powerwall Display

Today, analyzing large data sets using conventional computer systems is very difficult. This is because resolution of the ordinary computer is limited. In such situations, Powerwall display can be used. Also, large amount of data is generated and stored every day. After storing the data, it is necessary that it has to be analyzed.

Powerwall as a display allows multiple persons to view the data simultaneously. The data can be analyzed very clearly because of its high resolution. It is sensitive to multi touch, so several users can interact with the powerwall simultaneously.  The images displayed on the powerwall can be manipulated infront of the powerwall as well as on any other connected devices. For real implementation of powerwall environment, it requires following components.

• A Server to manage the communication between all devices,
• Data providers providing the data to be visualized;
• Client is required to visualize the desired data.

In powerwall, the information content depends upon the pixel. As resolution increases, the information content also increases. The size of the wall is very large, having 6-40 feet width or even larger and height over 9 feet. Today, powerwall and other large high resolution displays are also known as gigapixel displays. The interaction with powerwall is entirely different from conventional desktop displays. We all know that it is difficult to find a standard size mouse pointer from a very large display. This limitation can be minimized by using specific interfaces to the wall that use touch sensitive displays, wireless controllers, stylus etc.

The powerwall is used in many sites such as National Centre for Supercomputing applications, Pennsylvania state university etc. University of Leeds uses powerwall for analyzing medical data, complex transportation data etc.  At University of Leeds, they constructed two such displays.  One is a 28 panel, a 53.7 megapixel wall, 3 meter across and other is a 12 panel, 23 megapixels, 1.7 meter across. Figure below shows 53.7 million pixel Powerwall at the University of Leeds. The powerwall is constructed by the members of Visualization and Virtual Reality (VVR) research group in the school of computing at University of Leeds. They covers functional programming, human computer interaction, and virtual reality applications which includes medicine, transportation etc.

Design of Powerwall Display

The Powerwall is constructed by using several LCD panels aligned side by side. The main components are Motherboard, CPU, Graphics Card, RAM, and Hard Disk. Lightweight aluminum is used for constructing frames. It has a steel base for stability and a large display projection screen is placed. A channel separation is maintained to produce 3D effect on the powerwall. The projector is usually placed at the back of powerwall. The necessary inputs are provided by rendering cluster. Rendering is one of the interactive areas in computer graphics. It creates images which helps the user to interact with the virtual environment.The image is displayed on the projection screen with high resolution. It allows the user to analyze the images or data which is displayed. The projectors can produce the images with high resolution. The projectors get input from the graphics card. The user can easily analyze large amount of data using powerwall. The data is divided into smaller groups. Each group can be analyzed by each user on the powerwall simultaneously. The new groups displayed in private space such as tablets, laptops etc or public space such as powerwall. The user can move the images from private space to public space to display it on the powerwall.

The applications run by using Chromium, VRJuggler and MPI-GL (Message Passing Interface). Chromium is developed from WireGL. It was a research project at Stanford University Computer Graphics Lab. VRJuggler was developed by Iowa State University. It is a virtual platform for virtual reality (immersive) applications. The image viewer is created for loading images and these images are displayed on the powerwall display using VRJuggler.  These tools support Windows, Linux etc. The memory usage of graphics card is cut by compressed images. Images are first converted into pyramid tiled TIFF (Tagged Image File Format) files. It is a computer file format for storing graphic images. Then it is displayed on the powerwall display using image viewer. The image is scaled as one pixel in the power equals to one pixel in the image. Then the images are loaded. The user can zoom in or zoom out the images, analyze the images etc. Chromium is an open source browser project which is safer, faster etc. The chromium supports the powerwall displays. Chromium can run any applications without any modifications in the program. VRJuggler is an application tool that support desktop or powerwall applications without any further modifications in the code. MPI-GL is a library tool which is enabled, if any limitations occurred in the performance of Chromium. It is a message passing interface system which consists of parallel computers.  It takes a normal OpenGL program. It is turned into MPI program. Then synchronizing and modifying the unmodified program to work on the powerwall.

Applications of Powerwall Display

• Medical Imaging

The powerwall has so many applications. It can use in medical image analysis. Figure below shows the virtual reality powerwall at University of Leeds. The image of skin tissue is displayed on the powerwall. The original size of the tissue is about &.5mm*4mm.  The tissue is analyzed to find the disease is called Histopathology. The piece of tissues in the glass slide is examined using microscopes to diagnose diseases like breast cancer. The glass slides are scanned at very high resolution (200,000 dots per inch) producing digital images called virtual slides. The virtual reality powerwall displays the high resolution images of tissues in virtual glass slide.     

• Library Halls

Powerwall can be used in library halls which displays different library books. It helps to find the books easily. It will display the cover page of the book in the powerwall. The customer can select the book according to their interest. Figure below shows the powerwall in library which display the cover page of books in different categories.

• Manufactures

Car manufactures can view the new models in full size using powerwall display. It gives the 3D models of car which helps the manufacture to analyze the model. Figure below shows the 3D model of a car displayed in the powerwall.

• Industries

The high resolution and brightness of powerwall helps in several industries to view the images such as automotive, aerospace, oil and gas industries, national labs and academic research. Figure below shows the use of powerwall in the oil and gas industry.

• Video conferencing, real time graphics sharing, etc.  

• Powerwall can be used for analyzing large data set such as analyzing election results, customer data or stock exchange prices. This large volumetric data is displayed in the large screen. It helps the user to visualize and analyze the data easily.
• Powerwall is used for watching high resolution movies in theatres. It will be a great visual experience.

Researches are still going on to develop good resolution powerwall. Several institutions and research organization built powerwall for intended applications.

Advantages of Powerwall Display

• High resolution
• Brightness is high.
• Multiple user can interact with the powerwall simultaneously
• The user can control the images and menu in the display by using gestures or motion.
• Good Color contrast.

Disadvantages of Powerwall Display

• The single display of powerwall is created with several LCD panel aligned side by side. Due to this synchronization error may occur between the images in the large display of powerwall. 
• The powerwall is very large in size. So it is difficult to move from one place to other.
• If the user is unfamiliar with the structures and doesn’t have any idea about the clustered displays. Then it is difficult for doing presentations using powerwall.
• Before collaborative presentations, the users must preplan about the image location in the large display.