INTRODUCTION

• Basic visualization problem:
  - Interactive viewing of large 3-D industrial models
  - E.g., aircraft, submarines, model of a building or city.
• Increasingly used in the design-cycle
  - avoids or delays the expensive physical mockup
• Research Issue:
  - to provide effective techniques for video-rate interactive display
• Assume: polygonal surface models.
• Brute force method:
  - send every polygon to graphics pipeline.
• Next technique: visibility culling
  - useful in architectural models.
• Level-of-Detail (LOD) or Hierarchical Models: our focus.

Earliest work is Clark's paper [1] on hierarchical modeling. Other influential work are Rossignac and Borrel's paper [3] on the vertex clustering approach, Teller and Sequin's work on architectural walkthrough [4].