honours graphics 2008 session 12. today’s focus non-photorealistic rendering …other topics...

Honours Graphics 2008

Session 12

Today’s focus

• Non-photorealistic rendering

• …other topics requested in class…

Non-photorealistic rendering

• Sometimes graphics applications require the use of non-photorealistic rendering to achieve some effect (artistic expression, alternate spectrum rendering, etc)

• For example: cel-shading, pencil etching, calligraphy (japanese big brush style), etc

Non-photorealistic rendering

False color imaging

Non-photorealistic rendering

Pencil sketching Quake

Non-photorealistic rendering

Artistic impression

Non-photorealistic rendering

Calligraphy (Japanese Big Brush)

Non-photorealistic rendering

Cel-shading

Cel-shading

• Also “cell-shading” and “cartoon shading”

• 3D impression of models in traditional cartoon-style lighting, along with pronounced contouring

Cel-shading, how-to

• Quite easy to do even on older graphics hardware

• Two parts: lighting and contouring

Cel-shading, how-to, cont.

• Lighting follows the classic diffuse model, but the resultant color value is instead indexed into a one-dimensional array; instead of

a blocky lighting array is used

Cel-shading, how-to, cont.

• Contouring is done through inverse backface removal

• First render model normally using cel-lighting

• Set to render black wire-frame• Set lines to render thick• Set to cull front faces• Render model (z-buffer handles

elimination of invisible contours)

Cel-shading, result

Topic defined by students

• …