Five Focus and Context Awareness Techniques

A set of five focus and context awareness techniques were developed to deal with the four groups of problems identified through the users studies described in the previous chapters. These five techniques utilize the two layers of MLD to display different types focus and context awareness information on top of one another. Even though the focus and context information can be displayed on both the front and back layers or interchangeably between them, it was decided to use the front layer of MLD to display information related to the objects of interest (i.e. focus) and the back layer to display information related to the context. This was decided based on the work by Masoodian et al. (2004) who have used MLD to provide a focus and context awareness environment for editing Microsoft Word™ documents. In this application, the main document page view (i.e. focus) is presented on the front layer of MLD while the overview (i.e. context) of the entire document is displayed on the back layer. The transparency of the front layer supported by the MLD makes the task of viewing the overview of the document on the back layer possible.

The five new focus and context awareness techniques that have been developed here using MLD are:

 Object Isolation

 Component Segregation

 Peeling Focus

 Slicing

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As will be discussed in the following sections, the object isolation technique is designed to be used in both object and component editing modes, the component segregation is intended to be used in component editing mode, and the peeling focus, slicing, and peeling focus and context are intended to be used in object editing mode. 6.3 Object Isolation

The object isolation is a technique used for separating the object of interest from the rest of the model. It is intended to be used when modelers need to shape an object which is overlapping with other objects within a model. For example, in a 3D human model, an internal organ such as the heart is hidden within the skin and skeleton, and therefore shaping it with the other objects around it can be difficult. In this case object isolation can be used to separate the heart from the rest of the model.

The object isolation technique works by presenting the selected object (i.e. the object of interest) and the non-selected objects on different layers of MLD. The object of interest is shown on the front layer while the other objects are displayed on the back layer. By separating objects into two layers, modelers can perform tasks on the object of interest in a less crowded environment. The transparency of the front layer permits the overall context of the model relevant to the task being performed to be seen. This technique is designed such that the same panning and zooming effects are applied to objects on both layers. It should therefore be possible for the viewer to establish a continuous relationship between the object of interest and its context as the object moves during the navigation and manipulation processes.

Figures 6.2 to 6.5 illustrate4 the use of the object isolation technique in object editing

mode. Figure 6.2 shows the initial view of a 3D car model, where the car body (in brown) and its internal parts are visible to the viewer. As shown in this figure, the outmost parts of the model including the main body, side mirrors, tires and rims are engine, seats, etc. are shown on the back layer. The objects shown on the front layer are displayed in solid mode, and the objects on the back layer are in wireframe mode with edges colored in blue.

4 _{Throughout this chapter, screen shots will be presented to illustrate how a model is displayed on the MLD using its two layers.}

In most cases, the screen shots consist of a set of three images. The two on the top show the separate images displayed on the front and back layers of MLD side by side. The figure on the bottom is the actual photograph of the model being displayed on MLD. A demonstration of the individual technique has been provided in the enclosed videos.

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Figure 6.2: The initial condition of the model before the object isolation technique is applied

Figure 6.3: The steering set is selected on the back layer, and colored yellow

Figure 6.3 shows the steering set, which is comprised of the steering wheel, rods, and a wheel joint, is selected. The color of the selected objects change to yellow while the non-selected objects remain in blue. Once the object of interest (i.e. focus) is selected it can be isolated from the rest of the model (i.e. context) by using the object isolation

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technique. As the result of this, the steering set is transferred to the front layer, as shown in Figure 6.4.

Figure 6.4: The steering set which was initially displayed on the back layer is transferred to the front layer after object isolation technique is applied

Figure 6.5: The steering set shown on the front layer is edited in object editing mode

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in either the object or component editing modes. Figure 6.5 shows the object of interest on the front layer in object mode, and Figure 6.6 shows it in component editing model, where its edges and vertices are shown in red.

Figure 6.6: The object of interest is being edited on the front layer while context of the model is shown on the back layer