The GeoViewer provides a 3D interactive view of rock strata, for mine planning and other geological applications. The user can position the viewpoint anywhere in the space and see rock layers as graphical objects. Color and texture show the material of the rock layers, and a mouse click will pop-up a text box describing the material at a point. Hidden structure can be seen through transparent surfaces, and wire-frame views speed up interactive changes in the viewpoint. However, it can be difficult to see the identity of the rock layers in the various visual modes, and pop-up text obstructs the view.

impact granite limestone shale marble
abstract granite limestone shale marble
verbal granite limestone shale marble

The question "what type of rock is this?" has four nominal answers: granite, limestone, shale, and marble. This information is local to a point, and absolute identification enables attention to remain on the task, without a switch to a reference. The TaDa requirements were used to look-up everyday examples with similar task and data structure from the EarBenders database. The three best matches were shaking cereal containers to determine the contents, kicking garbage bags at a recycling depot to sort them, and listening to the weather outside the tent to decide whether to sleep-in. If the semantics of the sound design are not obvious, then one of these examples may suggest a suitable everyday scheme. Otherwise it may be necessary to fall back on an "abstract" scheme of musical instrument timbres. The examples also provide auditory structure which may be analyzed for regularities that may inform the sound design. Perceptual aspects that are common to all the examples, such as {Sound Type = categorical}, were copied straight into the sound design, and are shown with an asterisk in Table 1.

Scenario Description
Requirements Analysis
Sound Design
TitleMining ExplorationGeneric?what is it?Answersdifferent types*
StorytellerChris G.PurposeidentifyNaturenon-verbal*
Question ?what rock is it?Task Type DiscreteStreamssingle*
AnswerCoal, sandstone Task Style exploration Occurrence isolated
Elementsrock typesInfo LevellocalPatterndiscrete

Info RelationabsoluteMovementstationary

Info TypenominalTypecategorical*

Data TypenominalCompoundintegral*


The rule-base suggests that perceptually-equally-different timbres can represent categorical information because they do not imply a spurious ordering of the elements. Personify was used to choose four equally different timbres. The display device is a palette of musical instrument samples played on a Sun workstation. Each rock was arbitrarily assigned an instrument timbre at constant pitch and brightness: granite = cello, limestone = tenor sax, shale = English horn, marble = trombone.

The GeoViewer plays a one-second sample of an identifying timbre when the user taps on a rock with the mouse. A rock strata that is difficult to visually identify can be heard, without having to divert visual attention to a text. An unexpected advantage became apparent when the interface was used. The sounds allow the front-most surface at an intersection of strata to be disambiguated by tapping there, saving on a distracting and computationally expensive change of viewpoint operation. A development could provide information about the number and material of overlapping hidden layers.