Augmented Reality(AR) is used in our daily life in different ways. In our daily life, the use of AR is increasing and gaining popularity within the society. AR systems are the combination of the real scene viewed by the users and the virtual scene generated by the computer. Combine real scene and virtual scene provides rich, relevant and meaningful information to the users. AR combines three features, combining real and virtual reality, interactive in real time and registered in 3D. To work successfully in the real-world AR offers easily clear and natural information for the users. AR needs less equipment a camera to capture the real world, a display to see the output, and devices to provide some computational power, these devices consist of PC with HMD (head mounted display), Tablet PC, personal digital assistants (PDA) and smartphone.
Augmented Reality Systems
There are many ways which AR using and takes information about the surrounding environment. AR views the real environment and superimposed computer generated objects to the real world by two methods marker-based and markerless.
Marker-based Augmented Reality
Marker-based AR systems using a camera and visual markers. On the base of this visual markers, it controls the center, orientation, and range of its spherical coordinate system. Markers are black and white which is the simplest types of AR that comprise 2D barcodes. There are different shapes of markers, the structure of marker is a white background and black squares. AR using a camera to detect markers as the location for 3D objects.
Markerless AR systems use positional data such as GPS, compass or image recognition. This function anywhere without the use of special markers and have wider applicability. Markerless AR uses any part of the real environment. This uses natural features instead of special markers to augment information.
Augmented Reality Displays
Like other technologies, AR also needs some devices to achieve the goal. These devices consist of input devices, computers, tracking, and displays. The display technology is possibly classified into three categories. This is based on their position between the viewer and the real word. The displays technology consists of head-worn or head-mounted displays, handheld displays, and spatial displays.
Head Mounted Displays (HMD)
HMD displays are attached to users heads; the structure of HMD displays is like a helmet. there are two small displays that are attached to a helmet or eyeglasses and displays information which are virtual or AR images. Due to high-cost HMD are not ideal for education but usually using in military, engineering, and games.
For AR, handheld displays are good compared to HMD displays. These are socially acceptable and available all over the world because these are small devices with computer software. Tablet PCs, cell phones, smartphones, and PDAs are handheld displays these are suitable for AR systems because they have a camera, GPS, compass, and marker system. This is also popular devices for education purpose.
Spatial displays are a good option for applications which not need to wear anything. This using video projectors, optical elements, and other tracking technologies to display information to the users. it integrating the technology into the environment.