On EffectiveObject Manipulationin Virtual Environments

making scene design easier

Introduction Problems we are facing Simplification methods currently in use Methods of semantic snapping

and automated scene generation

In the beginning…

However, people always want more.

Problems we are facing

Simple scenes are unrealistic To achieve realism, we need to design

scenes that are much more complex Computing power grows rapidly Designer power stays limited

Evolution of design in video games

Problems we are facing

Scenes that took 2 man-days to lay out fifteen years ago may now require one man-month or more to satisfy the viewers

Simplification methods are a must – we need to introduce methods for effective object manipulation

Freedom of motion

When moving an object around in 3D space, we have 6 degrees of freedom:

Restricting the movement

Having all six degrees of freedom complicates precise manipulation

We need to use some constraints to restrict the object movement

One of the few options of restricting object movement in today’s editors is snapping

Basic snapping

Ordinary snap tools utilize a grid of regularly-placed points to snap to

Basic snapping makes design more precise…

…but not faster… …because all parts of the scene are

equivalent in terms of snapping

Advanced snapping

Advanced techniques attach objects to other scene objects instead of pre-defined set of points

Given no semantic information, the system still cannot determine the most appropriate object placement

This can lead to some unpredicted and undesired consequences

Adding semantics

We will provide the system with information on where each object belongs

e. g. “desks usually stand on the floor”, “a chair goes in front of a desk”

With a capable solver, the problem of placing an object into an appropriate position is thus reduced to moving it only roughly into the desired place

Adding semantics

The constraints may be represented using two sets of polygons for each object

Offer areas Binding areas The job of the solver is to take the object

being moved and align its binding areas with nearby offer areas

Adding semantics

Once two objects are properly aligned, they enter a parent-child relationship

When the connected objects are “torn” apart, this relationship is cancelled

This allows for dynamic forming of groups without the user even noticing

By moving the parent of a group, the user can move the whole group

Advantages of semantic snapping

We can specify which areas may or may not be connected by creating a semantic hierarchy

By carefully choosing binding and offer areas, we may prevent some object interpenetrations even without full-scale collision detection

We may even have the solver lay out the scene automatically

Thank you for your attention