2. Virtual environments (VEs)
"A VE is a computer-simulated world, consisting
of software representations of real or imagined
agents, objects, and processes; and a human-
computer interface to deploy and to interact
with these models.“
(Furness and Barfield, 1995)
3. Background
• In the 60’s computers and graphics were
developed.
• The U.S. military looked to create a new radar
system that would process large amounts of
information and deploy them immediately so
that humans could understand this
information quickly.
• The result was the radar defense system,
considered the first information simulator.
4. Background
• Also for the United States military, the
scientist Ivan Sutherland, one of the pioneers
of the Internet and computer graphics,
created in 1962 the first drawing program
called "Sketchpad".
7. Animation
• In the 80's, borrowing, but also creating many
Hollywood special effects techniques,
scientific visualization moved towards
animation.
• With the rise of video games in this decade,
an interface was created to detect the
movement of the user's hands, the virtual
reality glove.
9. Applications and uses
• Leisure industry
• E-commerce
• Medical Applications
• Training and learning
• Simulation and architecture
• Collaborative work environments
11. Three-dimensional (3D) scenarios
• The first 3D film, "The Power of Love", was
made in 1922.
• The popularity of 3D technology in film or
television has ups and downs.
• Its basic principle is to display an image for
each eye, that is, a stereo image.
12. How we see 3 dimensions?
• Humans have a binocular system because we
have two eyes.
• Binocular vision allows us to determine how
far objects are within a distance between 6
and 7 meters.
• Among several objects in our field of vision we
can automatically tell which are farther away
or closer.
13. How we see 3 dimensions?
• If we look with only one eye, we can still
distinguish the distance, but the accuracy
decreases and we have to depend on other
visual signals making the perception of the
distance slower.
14. How we see 3 dimensions?
• The binocular vision system relies on the fact
that our eyes are separated by an average of
about 5 centimeters, so each eye sees the
world from a slightly different perspective.
• Our brain has the ability to correlate the
images we see with both eyes.
15. Artificial 3D
• To achieve this artificially, there are currently
two main methods: passive and active form
lenses.
• Passive lenses do not require a power source
and are commonly used in cinemas.
• The screen displays two images, and the
lenses cause one image to reach one eye and
the other image to reach the other eye.
16. Passive lenses
• The most common methods are:
1. Anaglyphs using colors
2. Polarization
• Linear, which requires keeping the head in a vertical
position. One eye has vertical polarization, and the
other eye has horizontal polarization.
• Circular, which requires a special projector.
17. Active lenses
• LCD (Liquid Crystal Display) shutter glasses
open and close each lens. The separation is
not simultaneous, and the frame rate is
divided.
• Head-mounted displays (HMDs) have a
separate display for each eye.
18. Three-dimensional graphics
• The three-dimensionality of space can be
captured in a two-dimensional space, as it
happens in photography or in painting,
through the use of perspective and the
handling of light.
19. Three-dimensional graphics
• To generate 3D images on a computer screen,
a geometric representation of the information
is used, typically in a Cartesian coordinate
system.
• This process adds 3D qualities such as
shadows, color variations, and shape.
• This is known as rendering, which can be
translated as "interpreting" to provide the
necessary lighting and perspective.
20. 3D Models
• To obtain three-dimensional graphics, data
files called 3D models are created.
• A 3D model is the mathematical
representation of any three-dimensional
object and technically is not a graphic until it
is displayed.
21. 3D Models
• A model can be visually displayed as a
bidirectional image through 3D rendering or
using a non-graphical computer simulation
and certain calculations.
22. The phases of 3D graphics
1. Modeling: This is the process of creating a
computerized model in the shape of an object.
2. Rendering and Animation: This phase refers to
the movement and placement of objects within a
scene.
3. Rendering or Interpretation: This involves the
computational calculations that generate the
final image based on factors such as lighting,
surface properties, and other qualities.
23. 3D Environment
• 3D models are placed in a scene, and to
manipulate them it is necessary to establish
coordinates.
• In a 3D space the smallest possible area to
occupy is called a point.
• Each point is defined by a unique set of three
numbers, which are its coordinates and
represent its location on an axis, an imaginary
line that defines a direction.
24. 3D axes
• The standard axes in 3D programs are referred
to as X, Y, and Z.
• The "width" axis is the X-axis, which extends
horizontally from left to right or vice versa.
• The "height" axis is the Y-axis, which extends
vertically from top to bottom or vice versa.
• The "depth" axis is the Z-axis, which extends
through space from back to front or vice
versa.
25. Coordinates 0,0,0
• These coordinates define the central point of
the virtual universe, also known as the origin
point.
• At these coordinates, the three axes intersect,
and from this point onward, the axes can have
positive or negative values.
26. Coordinate system
• This coordinate system is called the world
coordinate system and is used for software
applications. However, it can be changed as
needed or for control purposes.
• Two of the most common alternatives are
view coordinates and local coordinates.
27. Coordinate system
• Although the world coordinates themselves do not change,
the viewpoint from which the scene is observed can
change.
• For example, if instead of viewing the scene with the Z-axis
growing towards us, we view it from the opposite side, with
the Z-axis decreasing towards us, then the X-axis will
decrease to the right and increase to the left.
• A local coordinate system will use the object as a basis for
the axes, and each object can have its own coordinate
system. This is useful when you want to work in reference
to a specific object.
28. Scene orientation
• The scene can be configured as right-handed
or left-handed.
• In mathematics and physics, the right-hand
rule is a mnemonic used to understand
conventional notations for 3D vectors. This
mnemonic was devised by the English
physicist John Ambrose Fleming in the late
19th century and is used in electromagnetism.
29. Scene orientation
• There are variations of the mnemonic depending
on the context, but all variations are related to
the idea of choosing something conventional.
• In the representation of 3D space, three vectors
with a right-angle separation between them are
involved.
• There are two possible solutions, and therefore, it
is important to avoid ambiguity by specifying
which solution is being referred to.
32. User point of view
• The three-dimensional scene will look different
depending on the viewpoint from which it is
observed.
• To specify this viewpoint, the concept of a camera
is used.
• The position of the camera, typically associated
with the user's viewpoint, determines the field of
view from a certain point and with certain
coordinates within the scene.
33. Frustum
• The viewing frustum is the spatial region of
the scene that appears on the screen; it
represents the viewpoint of a theoretical
camera.
• The exact shape of this region varies
depending on the lens simulation being used,
but generally, it resembles the frustum of a
rectangular pyramid, which is why it is called a
frustum.
34. Frustum
• The planes that the frustum cuts
perpendicularly are the near plane and the far
plane.
• Objects that are closer to the camera than the
near plane or beyond the far plane are not
rendered or drawn on the screen.
Far plane
Close plane
35. Degrees of freedom (DOF)
• Objects can be translated by modifying their
distance from the origin point along one, two,
or all three axes: X, Y, and Z. These movements
constitute three degrees of freedom.
36. Degrees of freedom
• Objects can also rotate. The rotation of an
object around these three axes constitutes
another three degrees of freedom.
• The combination of translation and rotation
forms a total of six degrees of freedom.
38. Rotation
• Rotation around the object's own axis, center
of mass, or pivot point in a 3D model can
occur in three ways.
• When rotation is around the Y-axis, it is called
pitch. Rotation around the X-axis is referred to
as roll, and rotation around the Z-axis is
known as yaw.
39. Rotation around a pivot
X-axis
Z-axis
Y-axis
Center of
mass
“Pitch” rotation
“Roll” rotation
“Yawn” rotation
