BUMP-MAPPING SET09115 Intro to Graphics Programming Slide 2
Breakdown Background Review texturing and lighting Adding detail
Bump and Normal Mapping Examples Shaders Advanced Techniques
Parallax mapping Tessellation Slide 3 Recommended Reading Real-Time
Rendering Chapter 6, section 6.7 onwards For tessellation, see 13.6
Slide 4 Background Slide 5 Review - Lighting Lighting is the
technique we use to provide depth to our renders Three basic
lighting types Ambient Background light Diffuse Directional light
Specular Shininess Slide 6 Review - Textures Textures are just a 2D
grid of pixels we can use for other purposes For examples,
alpha-mapping We can use texture data in our shaders to perform
more elaborate effects Using texture data is one of the commonest
techniques for adding more detail to a 3D model Slide 7 Problem
Adding Detail We want detail The more detail the better How do we
get high detail renders in our game so we can see creases in
fingers, notches in swords, etc? Slide 8 Solution Add Geometry Easy
solution add more triangles Artists solution More triangles means
more geometry means higher quality So job done, right? Slide 9
Problem Processing Geometry Problem is processing high poly count
models Typically try and keep characters down to 25,000 High number
of triangles means it takes longer to render Fine for non-real-time
applications Games we need better techniques So how do we add
detail, without adding geometry? Slide 10 Cheating with Lighting
Effectively, we have already been doing this Lighting cheats Phong
shading is an example We need techniques which allow us to
manipulate the light to make it look like there is detail Slide 11
Options Bump Mapping Normal Mapping Relief Mapping Parallax Mapping
Slide 12 Questions? Slide 13 Bump and Normal Mapping Slide 14 Bump
Mapping Bump mapping is the technique used to add detail to a
surface Think roughness / texture Bump mapping is the simplest
technique for adding detail using textures Slide 15 Bump Map A bump
map is just a black and white image that is used to modify the
surface a model to provide a rough look Detail is very fine,
surface level Think cloth texture Slide 16 Video Example
http://www.youtube.com/watch?v=HR422RXjw-Q
http://www.youtube.com/watch?v=HR422RXjw-Q Slide 17 Procedural Bump
Mapping Frag Shader vec3 litColour; vec2 c = BumpDensity *
TexCoord.st; vec2 p = fract(c) vec2(0.5); float d, f; d = dot(p,
p); f = inversesqrt(d + 1.0); if (d >= BumpSize) { p = vec2(0,
0); f = 1.0; } vec3 normDelta = vec3(p.x, p.y, 1.0) * f; litColour
= SurfaceColour.rgb * max(dot(normDelta, LightDir), 0.0); vec3
reflectDir = reflect(LightDir, normDelta); // Use reflectDir as
relection normal Slide 18 Normal Mapping Normal mapping extends on
the bump mapping technique to create a more shaped detail Think
brick work rather than low level surface Slide 19 Normal Maps
Normal maps use RGB as their texture colours Depending on the
colour, the lighting model determines the normal of the model at
that particular point of the texture Slide 20 Video Example
http://www.youtube.com/watch?v=pQS2m18ebEI
http://www.youtube.com/watch?v=pQS2m18ebEI Slide 21 Normal Mapping
Shader Normal mapping shader works similarly to the bump mapping
shader Typically, we add specularity as well Main difference is
that our normals are more than two values, allowing a more
realistic lighting effect Slide 22 Questions? Slide 23 Advanced
Techniques Slide 24 Relief Mapping Relief mapping is where we add
detail using a texture, but actually manipulate the geometry to
create the detail Actually, we talked a bit about relief mapping
for terrain generation last week We are manipulating a 3D plane
into our 3D terrain Relief mapping is useful, but more expensive
Slide 25 Relief Map Example
http://www.youtube.com/watch?v=5gorm90TXJM
http://www.youtube.com/watch?v=5gorm90TXJM Slide 26 Parallax
Mapping AKA virtual displacement mapping Uses the viewer position
to retrieve different pixels from the texture based on the height
field Slide 27 Video Example
http://www.youtube.com/watch?v=R4vIQobnegk
http://www.youtube.com/watch?v=R4vIQobnegk Slide 28 Displacement
Mapping Essentially relief mapping Proper relief mapping has the
ability for self- occlusion and self- shadowing Technique requires
geometry to be added to a model Tessellation Slide 29 Tessellation
The big new addition to DirectX 11 Triangles are added or removed
based on how close the viewer is Think like mip-mapping, but for
models Not like normal LOD where different models are used Slide 30
Video Example http://www.youtube.com/watch?v=-uavLefzDuQ
http://www.youtube.com/watch?v=-uavLefzDuQ Slide 31 Questions?
Slide 32 To do this week Practical this week is on texturing I need
to tweak the one on WebCT a little I know 3 rd years have MAD CW
due this week Get it out of the way so you can move onto this one I
wont be producing a practical on bump mapping If interested,
investigate yourself Slide 33 Summary Adding details to a render is
where current game technology is focused Model complexity cant go
much further on current generation hardware Various techniques
allow us to modify a render to provide detail Bump mapping, normal
mapping, etc. There is a cost, but usually less than adding
geometry
