清华大学：《计算机图形学基础》课程教学资源（授课教案）纹理映射

Texture • Texture – Texturing is a fundamental technique in Computer Graphics, allowing us to represent surface details without modeling geometric material details. – We will describe the basic ideas and applications of texture in this course

Texture • Texture Left Image (Without texture) ,Right Image (With texture) ,Note the differences between two images. The right one is more realistic

Texture • Why we need texture? – Modeling surface details is one of the most important tasks for rendering realistic images. • For example, if we want to model a brick wall. • One option: use a huge number of polygons with appropriate surface coloring and reflectance characteristics to model the surface details

Texture • Why we need texture? – However, in most applications, few people would care much about the details of the brick wall and would normally view the wall from a distance. – In this situation, we probably don’t need to know all the details of the brick wall. Instead, we can simply model the wall as a big flat polygon, and paste onto the polygon a wall image so that the polygon looks like a real brick wall

Texture • What is Texture? – This image, which is an approximation to the real brick wall, is called texture in graphics – The process of applying the texture to an object surface is called texture mapping (纹理 映射) or texturing (贴纹理)

Texture • Why texture is useful? – Texturing resolves the two problems. • First, by representing the surface as a texture image, you don’t have to painfully model all the geometric and material details. This saves time and resources and allow users to do other more important things

Texture • Second, by rendering a rough polygonal model (e.g. a single square polygon for a brick wall) and a texture instead of a detailed geometrical model with different BRDFs, the rendering can be done much more efficiently, either via ray tracer or hardware . This saves computers time and resources

Texture • Why we need texture?

More texture example

Original Model