Mathematical Optimization in Graphics and Vision - Luiz Velho - Impa
Mathematical Optimization in Graphics and Vision - Luiz Velho - Impa
Mathematical Optimization in Graphics and Vision - Luiz Velho - Impa
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1.4. REVISITING THE DIAGRAM 13<br />
1.4 Revisit<strong>in</strong>g the diagram<br />
Now that we have discussed the concept of graphical object, it is time to go back<br />
to the diagram of Figure 1.2.<br />
Every output graphics device has an <strong>in</strong>ternal representation of the class of<br />
graphical objects that the device is able to display. The space of graphical objects<br />
with this representation is called the representation universe of the graphical<br />
display. As an example, the representation universe of a regular personal computer<br />
(graphics card + monitor) is a matrix representation of an image. Thus, for<br />
each output graphics device, the operation of visualization on the device consists<br />
of an operator R: O → O ′ from the space of graphical objects to be displayed, to<br />
the representation universe of the graphics display.<br />
Besides the generic visualization operation described above, we have the operations<br />
of graphical object description, graphical object process<strong>in</strong>g <strong>and</strong> graphical<br />
object analysis. This completes the elements to obta<strong>in</strong> a generic diagram for<br />
graphical objects, the conta<strong>in</strong>s, as particular cases, the diagrams <strong>in</strong> Figures 1.2<br />
<strong>and</strong> 1.3.<br />
1.5 Description, representation <strong>and</strong> reconstruction<br />
In this section we discuss the three most important problems related with graphical<br />
object:<br />
• How to describe a, cont<strong>in</strong>uous, graphical object?<br />
• How to discretize a graphical object?<br />
• How to obta<strong>in</strong> a cont<strong>in</strong>uous graphical object from one of its discretizations?<br />
1.5.1 Description<br />
Describ<strong>in</strong>g a graphical object consists <strong>in</strong> devis<strong>in</strong>g its (cont<strong>in</strong>uous) mathematical<br />
def<strong>in</strong>ition. Therefore, this is a problem posed <strong>in</strong> the mathematical universe. Depend<strong>in</strong>g<br />
on the nature of the graphical object this topic an important one <strong>in</strong> different<br />
areas of computer graphics. The description of the geometry <strong>and</strong> topology of