Textures

Question 1

What do we do when the Pixel Resolution is larger than the Texel Resolution, ie the Pixels are smaller than the Texels ?

Answer 1

In this case we have multiple pixels mapping to the same texel

1. No Filter

In No Filter we simply select the texel to which the pixel maps, the result can be quite blocky

2. Bilinear Interpolation

We find the fractional co-ordinates in the Texture

We then find the neighbours of the co-ordinates and take the average, this leads to the image being slightly blurred

Question 2

What do we do when the Pixel Resolution is smaller than the Texel Resolution , ie the Pixels are larger than the Texels?

Answer 2

This means that pixels next to each other may map to texels that are far apart from one another

1. MipMap Filtering

Instead of using a single texture map, we have a set of them with different resolutions

We can then choose which texture to use based on how far (the z-value) the object is

The further an object is the less detail we need

Question 3

What are light maps?

Answer 3

We can save rendered surfaces as textures as light maps, and this saves us time

Question 4

What is bump mapping?

Answer 4

In bump mapping, we do not alter the surface colour but rather the surface normals

This is so that our illumination model shades it differently to give the surface a different looking texture

Question 5

How do we figure out the surface normals in a bump mapping?

Answer 5

We can use a texture map

We may use the gradient in a texture map to figure out the surface normals in a texture map