Development of an Augmented Reality system using ARToolKit

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Development of an Augmented Reality system using ARToolKit and user invisible markers proposal was found out to lack the right properties. This transmittance graph is shown in Figure 4.33. Figure 4.33 Proposed transmittance graph This would be a better solution than the one explained before. First of all, the total weight will be significantly lower. Also, there should not be any thoughts about how to mount the filter in a fixed position. Simply the filter is attached to the camera, like a micro lens, or C/CS mount lens would be. It will be at the right position, without having the problem of finding a way to put it in parallel with the CCD plane and avoiding light to pass. 4.5 AR HMD system Now that have been described the components for invisible marker tracking the results of the search for suitable HMDs are laid out now. The way the results are presented will only focus on the main aspects of the found hardware. Only an overview is given to keep things clear and to save the reader from skipping through secondary information. First will be described three video see-through HMD systems, followed by another type of HMD, an optical see-through HMD. Hereby needs to be noted that one should be careful with the stated data on FOV of the HMD; these can be measured horizontally, vertically or even diagonally. When the way the FOV is measured is known, this is mentioned. 4.5.1 Video see-through This type of HMDs uses two cameras to capture a scene. The images from those cameras are displayed on the two microdisplays of the HMD. To create Augmented Reality these images are overlaid with virtual objects. ARVision3D manufactures a full stereo HMD which is available in two kinds; either as an ARVision3D HMD or as an ARVision3D Goggles model. Both make use of two colour cameras to provide the stereoscopic vision ability. No synchronization of the cameras is needed. The view is presented to the user through two SVGA micro displays with 480,000 pixels, equal to 800x600 resolution. Refresh rate of the HMD is 120Hz flicker free. The FOV that the cameras deliver is approximately 40° diagonal (4:3, 32° horizontal, 24° vertical). The weight of the device is 120 grams. Together with HMD or 51
Development of an Augmented Reality system using ARToolKit and user invisible markers Goggles is delivered a power unit that interfaces with a computer. Price is €7300, at http://inition.co.uk/indexf.htm. In Figure 4.34 and Figure 4.35 are shown both models; HMD and Goggles. Figure 4.36 displays the power unit. Figure 4.34 HMD model Figure 4.35 Goggles model Figure 4.36 Power Unit The first described HMD and Goggles are a complete all-in-one solution. Now will be described a device that, together with an HMD also provides an all-in-one solution. The VideoVision has two colour NTSC/PAL cameras which deliver a video-out signal. These video signals connected to an HMD give it stereoscopic possibilities. Requirement is that the used HMD needs to have the ability to handle stereo input. The cameras have a resolution of 640x480 pixels. Each camera has a FOV of 78 degrees. Refresh rate is measured at 60Hz. The dimensions of the device are 185mm x 48mm x 47mm. Total weight of the device is 230 grams. The VideoVision needs to be used as an add-on to an HMD. The device is shown in Figure 4.37. The manufacturer advices to use it together with the nVisor SX HMD which is available at http://www.nvisinc.com. This HMD, depicted in Figure 4.38 carries a price of $23,900. It needs to be accentuated that of course other HMDs can also be used. The VideoVision costs $8,900, including a rendering computer with a NVIDIA GeForceFX6800 graphics card to connect the HMD. Figure 4.37 VideoVision add-on Figure 4.38 nVisor SX HMD The foregoing described a somewhat more elaborative solution. The HMD solution described now is also a bit more complicated. A Dutch company, http://cybermind.nl, sell HMDs and other type of VR equipment. One of the HMDs they have is the Hi-Res800PC, an HMD normally used for VR applications. Contact with the company has shown that they have the possibility to adapt the HMD in such a way that it can be used for AR. For obtaining this, two cameras need to be integrated into the HMD for capturing a scene. The images from the camera are processed by two video cards, so that a frame sequential stream of images is created. These images are fed back into the two micro displays which will create a stereoscopic view of a scene. The bare HiRes-800PC HMD, displayed in Figure 4.39, carries a price of €3275. 52
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