Lecture 12: Textures – Review Questions
Describe conceptually how texture can be applied to a triangle in a scene. Draw a
sketch to illustrate your answer.
Suppose you have a 800x600 image of a world map that is a Mercator projection
of the world. In other words, the map is laid out with latitude coordinates that
range from -90 degrees to 90 degrees and longitude coordinates from -180
degrees to 180 degrees. Compute the complete mapping from a latitude /
longitude value to a pixel element in the texture map. Reference pages 306 and
307 in the handout (Ch12) for additional details.
Suppose your resulting texture coordinates are (56.2, 73.6). Give an algorithm
that uses bilinear interpolation to compute a color from the pixels surrounding this
point. What are the relative contributions of all pixels surrounding this point to
the final color computed for this point? Draw a diagram to illustrate your
assumptions (e.g., what are the coordinates of the pixel centers of all neighboring
pixels).
Suppose you have texture coordinates (u,v) for each vertex of a triangle. Explain
how barycentric coordinates are used to determine the color at each pixel of a
textured triangle.
What are mipmaps and why do we use them?
Texture maps can be used to modify a wide variety of different values that may
vary over the surface of an object. List at least five different parameter values
that may be controlled using a texture map (i.e., five different ways in which
texture maps can be used to control object appearance).
What is a bump map? a normal map? a displacement map? an environment
map?
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