This document provides an introduction to 3D geovisualization and 3D rendering. It discusses the history of 3D rendering and some of the early models. It then covers basic 3D rendering methods such as wireframes, textures, raytracing, and polygon rendering. It also discusses how these methods are used for digital elevation models and building information modeling.

1. Introduction to 3D
Geovisualization
John Reiser

2. History
• Computer rendering of 3D images is a relatively
recent development.
• 3D rendering requires considerable processing to
generate photorealistic images.
• Until capabilities rose and costs dropped, 3D
rendering was often a task left up to
supercomputers.
• One of the first 3D models: “Utah Teapot”

3. Utah Teapot
• Designed and rendered
by Martin Newell in 1975
at the University of Utah.
• A standard white Melitta
tea pot.
• Originally didn’t have a
bottom.
• Reference data for testing
new applications.

5. 3D Rendering
• Let’s cover some basics behind 3D rendering.
• Several methods for drawing the 3D object.
• Constructing a model out of triangles.
• Rendering methods can be refined further with
textures and lighting effects.

6. Wireframes
• Most basic method of
rendering a 3D object.
• Vector representation
of a 3D object from a
specific vantage point.
• Edges are shown with
simplified faces.

7. Textures
• Textures are applied to
the faces of a 3D model.
• Textures can be a solid
color, image or
photograph.
• Textures can include
additional data, such as
noise, reflectivity or
bumps.

8. Raytracing
• Rendering method
employs algorithms to
simulate individual rays
of light and how they
interact with the object
and the environment.
• Light, shadows, focus,
etc can be modeled.
• Highly photorealistic.

9. Polygon Rendering
• The edges and faces are • Stanford Bunny
essentially 3D polygons. 69,451 polygons.
• The more complex the
polygon, the longer the
rendering time.
• The simplest polygon is
the triangle.
• Many renderers utilize
triangles to construct a
3D model.

10. Triangles & TINs
• Back to GIS, triangulated irregular networks are
digital elevation models based on nodes & edges
that form a mesh of triangular faces.
• Rendering landscapes instead of objects requires
georeferencing.

11. TINs versus Raster DEMs
• TINs allow for greater variation in the terrain
than raster.
• Raster cell sizes must be small to capture minute
variations, producing larger files.
• Gentle changes need only a few triangles to be
represented.

12. Building Models
• Wireframe models can
be covered with an
architectural rendering
or a photograph to
create a basic building
model.
• Details can be
introduced by adding
more textured faces to
the volume.

13. Building Information Modeling
• Highly detailed models of buildings, down to
interior spaces.
– HVAC, mechanicals, etc.
• Used for facilities management.
• Used to visualize maintenance, planning and
construction efforts.
• GIS for buildings.

14. Viewing 3D
• Several methods of viewing 3D images on a 2D
surface.
– Shutters
– Anaglyphs
– Free (cross eyes)
• Some 3D rendering software will create
anaglyphs for you.