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A DESIGNER’S GUIDE TO

3D direct manipulation and AIM “A direct manipulation interface allows the user to use a pointing device to “reach in and grab” objects in a 3D scene and move or change them in a natural, intuitive manner.” (Strauss, Schrag and Isaacs, 2002)

BENEFITS Direct manipulation gives immediate feedback to the user’s input motion. Focus stays in the work area instead of moving back and forth across the UI. Interactions become more natural and enjoyable. Click on a tools palette

or on the object itself.

Type into a text field

or grab a handle and pull.

CHALLENGES It’s not as easy as it sounds. Direct manipulation is more difficult in 3D than 2D. Watch out for issues with scale, level of detail, contrast and other perception problems.

Handles too big or small

Handles obscure the object

Handles don’t obey perspective

Is it far away or up close?

Which way does it move?

Level of detail doesn’t change

From “The Design and Implementation of Direct Manipulation in 3D,” Siggraph 2002 and “Designing Good Manipulators,” John Schrag


GEOMETRY Here are the basic categories of objects that can be manipulated in AIM.

Points

2D polylines

2D polygons

Extruded polygons

city furniture pipe connector points of interest

barrier pipeline railways roads trees [line] water [river]

building coverage trees [stand]

buildings

ACTIONS These basic moves are the foundation for all AIM manipulators. They can be combined or adapted to specific uses.

Rotate

Move (Translate)

Control points

Extrude height

Change elevation

AFFORDANCES What does it do? Display functionality to the user clearly. The appearance of the tool indicates the action it provides.

Highlighting

Texture

Shape

Dynamic tooltips

Ghosting

Rubber banding

FEEDBACK What has it done? When moving manipulators, users can see what changes they’re making in real time.

Jessamyn Miller Eric Fain ICP-UX Architecture December 2012


A designer's guide to direct manipulation