Systems for data processing, anaylsis and representation

Allam, Mosaad; Plunkett, Gordon

Bibliographic data

Monograph

Persistent identifier:: 1067490280

Title:: Systems for data processing, anaylsis and representation

Sub title:: ISPRS Commission II Symposium : June 6 - 10, Ottawa, Canada

Scope:: 1 Online-Ressource (XX, 530 Seiten)

Year of publication:: 1994

Place of publication:: Ottawa

Publisher of the original:: The Surveys, Mapping and Remote Sensing, Natural Resources Canada

Identifier (digital):: 1067490280

Illustration:: Illustrationen

Signature of the source:: ZS 312(30,2)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist aus dem Copyrightjahr ermittelt.

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Allam, Mosaad; Plunkett, Gordon

Corporations:: Symposium Systems for Data Processing, Analysis and Representation, 1994, Ottawa; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis; Kanada, Surveys, Mapping and Remote Sensing Sector

Adapter:: Symposium Systems for Data Processing, Analysis and Representation, 1994, Ottawa; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis; Kanada, Surveys, Mapping and Remote Sensing Sector

Founder of work:: Symposium Systems for Data Processing, Analysis and Representation, 1994, Ottawa; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis; Kanada, Surveys, Mapping and Remote Sensing Sector

Other corporate:: Symposium Systems for Data Processing, Analysis and Representation, 1994, Ottawa; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Instrumentation for Data Reduction and Analysis; Kanada, Surveys, Mapping and Remote Sensing Sector

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: [Friday, June 10, 1994]

Document type:: Monograph

Structure type:: Chapter

Chapter

Title:: [Joint ISPRS/GIS '94 Plenary V]

Document type:: Monograph

Structure type:: Chapter

Chapter

Title:: ADVANCED 3D VISUALIZATION TECHNIQUES COLIN WARE

Document type:: Monograph

Structure type:: Chapter

paper which will address the user interface and visualization issues. Before continuing, a small theoretical digression is in order. One of the most useful concepts in defining quality in user interfaces is J.J. Gibson's theory of affordances (Gibson, 1966). This is theory of perception which states that we do not perceive patterns of light and shade, or lines and edges, or motion flow. Instead what we have evolved to perceive are 'affordances' which may be described as possibilities for action, or use. This we perceive surfaces as having the potential for walking or sitting, we perceive objects as potential tools or potential food and certain complex environments as holding potential danger. The theory embeds perception in action, and as such it makes sense of a good user interface as one in which the user perceives the right set of affordances. Through it, with minimal instruction the user can perceive the affordances of the computer system he or she is expected to use. The system should also afford the easy execution of the tasks for which it was designed. —@— 2D (tb) —i— Stereo perspective (1b) —&— Stereo head coupled perspective (1b) —&— Head coupled perspective (1b) ed X 50 + % Error 0 50 100 150 200 250 300 Number of Nodes Figure 1. The results of a study of path tracing in an information network. Using a stereo, head coupled perspective view, as shown in figure 2. resulted in three times as many nodes being understood at the same error rate. We have recently obtained hard evidence that even for visualizing abstract information networks, where understanding the connectivity is important, visualizing in 3D is important (see Figure 1). However, it is not the fact that it is a perspective view that helps, but rather the enhanced space perception that comes from stereo viewing (which increases the size of the network that can be understood by 60%) and even more from motion parallax of the data (which increases the size by 120%). If motion parallax is combined with stereo viewing we find that three times the network size can be understood for a constant error rate. 488 2. METHODS AND METAPHORS FOR VIEWPOINT NAVIGATION Viewpoint placement, 3D scene exploration and virtual camera control are all aspects of the same problem in computer graphics, namely how to move the viewpoint in a virtual 3D scene. The kinds of task where this is important are molecular modeling (Surles, 1992), walkthroughs of architectural simulations (Brooks, 1986), camera control in animation systems, and flights over digital terrain maps representing subsea or remote sensing data (Stewart, 1991) as well as numerous CAD and advanced GIS applications. For a number of years we have been studying a six degree-of-freedom variant of the common mouse input device. We call it a Bat because a bat is like a mouse that flies (or fledermaus in German). The device senses both position (x,y,z) and orientation (azimuth, elevation and roll) information. In some studies we showed how this device could be used for object placement (Ware, 1990). However, more recently we have concentrated on using the Bat in ways that allow us to explore different methods and metaphors for virtual camera control. Often methods for viewpoint control are based on metaphors which help the user to get a conceptual grasp of the way the system will behave. Thus if the user is told that he or she is flying through the data, it is quite different than telling the user that the data is on a turntable which can be rotated. Most of the remainder of this paper is organized as a survey of different virtual camera control methods, both as employed in my research laboratory and by others. 1) Eyeball in Hand Metaphor and Camera controllers. The phrase "Eyeball In hand" describes a Metaphor in which the user directly manipulates the viewpoint as if it were held in his or her hand. The metaphor requires that the user imagine a model of the virtual environment somewhere in the vicinity of the monitor. The eyeball (a spatial positioning device) is placed at the desired viewpoint and the scene from this viewpoint is displayed on the monitor. Cognitive affordance problems arise from the difficulty some subjects have of imagining the model. Ware and Osborne, (1990) found large individual differences in this respect. Also, if the eyeball is pointed away from the screen the correspondence between hand motion and the image motion is confusing. Physical affordances are restricted by the physical limitation of the device space - it can be awkward or impossible to place the "eyeball" in certain positions. There is a non direct-manipulation variation on this theme which allows for complex camera commands of the kind a director might give to the cameraman. Recent work by Gleicher and Witkin (1992) explores the use of high level commands to give the user control over the directing the direct certain mi or zoom | approach which pos the user tc al, 1992). 2) World i In the "W changed t displayed rotated ck object on a Polhemus' rotations simultanec viewpoint single, rea the enviro enclosed ii does not affordance: center of rc interior the of being er hand moti (Ware and | The World the eyeball her viewpo Useful vari: virtual turni sphere (Ch from a mou direct man devices ten Often they the range o We are usi DEM visual 3) Function It is a comn common gr translate anc directly by include this | it does not e A much mc functions is MacKinlay, which corre surface, hah also evaluat movements,

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