parameterized environment maps ziyad hakura, stanford university john snyder, microsoft research jed...
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Parameterized Environment Maps
Parameterized Environment Maps
Ziyad Hakura, Stanford University
John Snyder, Microsoft Research
Jed Lengyel, Microsoft Research
Static Environment Maps (EMs)Static Environment Maps (EMs)
Generated using standard techniques:•Photograph a physical sphere in an environment•Render six faces of a cube from object center
Generated using standard techniques:•Photograph a physical sphere in an environment•Render six faces of a cube from object center
Ray-Traced vs. Static EMRay-Traced vs. Static EM
Self-reflections are missingSelf-reflections are missing
ParameterizedEnvironment Maps (PEM)
ParameterizedEnvironment Maps (PEM)
EM1 EM2 EM3 EM4 EM5 EM6 EM7 EM8
3-Step Process3-Step Process1) Preprocess: Ray-trace images at each viewpoint
2) Preprocess: Infer environment maps (EMs)
3) Run-time: Blend between 2 nearest EMs
1) Preprocess: Ray-trace images at each viewpoint
2) Preprocess: Infer environment maps (EMs)
3) Run-time: Blend between 2 nearest EMs
EM1 EM2 EM3 EM4 EM5 EM6 EM7 EM8
Environment Map GeometryEnvironment Map Geometry
Eye
N
ReflectionRay
EM Geometry
EM TextureMapping
EM Texture
(u,v)
Why Parameterized Environment Maps?
Why Parameterized Environment Maps?
•Captures view-dependent shading in environment
•Accounts for geometric error due to approximationof environment with simple geometry
•Captures view-dependent shading in environment
•Accounts for geometric error due to approximationof environment with simple geometry
How to Parameterize the Space?How to Parameterize the Space?
•Experimental setup•1D view space•1˚ separation between views•100 sampled viewpoints
•In general, author specifies parameters•Space can be 1D, 2D or more•Viewpoint, light changes, object motions
•Experimental setup•1D view space•1˚ separation between views•100 sampled viewpoints
•In general, author specifies parameters•Space can be 1D, 2D or more•Viewpoint, light changes, object motions
Ray-Traced vs. PEMRay-Traced vs. PEM
Closely match local reflections like self-reflectionsClosely match local reflections like self-reflections
Movement Away from Viewpoint Samples
Movement Away from Viewpoint Samples
Ray-TracedRay-Traced PEMPEM
Previous WorkPrevious Work
•Reflections on Planar Surfaces [Diefenbach96]
•Reflections on Curved Surfaces [Ofek98]
•Image-Based Rendering Methods•Light Field, Lumigraph, Surface Light Field, LDIs
•Decoupling of Geometry and Illumination •Cabral99, Heidrich99
•Parameterized Texture Maps [Hakura00]
•Reflections on Planar Surfaces [Diefenbach96]
•Reflections on Curved Surfaces [Ofek98]
•Image-Based Rendering Methods•Light Field, Lumigraph, Surface Light Field, LDIs
•Decoupling of Geometry and Illumination •Cabral99, Heidrich99
•Parameterized Texture Maps [Hakura00]
Surface Light Fields [Miller98,Wood00] Surface Light Fields [Miller98,Wood00]
Surface Light Field Surface Light Field
Dense sampling over surface points of
low-resolution lumispheres
Dense sampling over surface points of
low-resolution lumispheres
PEMPEM
Sparse sampling over viewpoints of
high-resolution EMs
Sparse sampling over viewpoints of
high-resolution EMs
Parameterized Texture Maps [Hakura00]Parameterized Texture Maps [Hakura00]
p1
p2
U
V
p1
p2
U
V
Ligh
tLi
ght
ViewView
Captures realistic pre-rendered shading effectsCaptures realistic pre-rendered shading effects
Comparison withParameterized Texture Maps
Comparison withParameterized Texture Maps
•Parameterized Texture Maps [Hakura00]•Static texture coordinates•Pasted-on look away from sampled views
•Parameterized Environment Maps•Bounce rays off, intersect simple geometry•Layered maps for local and distant environment•Better quality away from sampled views
•Parameterized Texture Maps [Hakura00]•Static texture coordinates•Pasted-on look away from sampled views
•Parameterized Environment Maps•Bounce rays off, intersect simple geometry•Layered maps for local and distant environment•Better quality away from sampled views
EM RepresentationsEM Representations•EM Geometry
•How reflected environment is approximated•Examples:
•Sphere at infinity•Finite cubes, spheres, and ellipsoids
•EM Mapping•How geometry is represented in a 2D map•Examples:
•Gazing ball (OpenGL) mapping•Cubic mapping
•EM Geometry•How reflected environment is approximated•Examples:
•Sphere at infinity•Finite cubes, spheres, and ellipsoids
•EM Mapping•How geometry is represented in a 2D map•Examples:
•Gazing ball (OpenGL) mapping•Cubic mapping
Layered EMsLayered EMs
reflector
local EM
distant EM
Segment environment into local and distant maps•Allows different EM geometries in each layer•Supports parallax between layers
Segment environment into local and distant maps•Allows different EM geometries in each layer•Supports parallax between layers
Segmented, Ray-Traced ImagesSegmented, Ray-Traced Images
DistantDistant Local ColorLocal Color Local Alpha Local Alpha Fresnel Fresnel
EMs are inferred for each layer separatelyEMs are inferred for each layer separately
Distant LayerDistant Layer
reflector
distant EM
N
Eye
R
Ray directly reaches distant environmentRay directly reaches distant environment
Distant LayerDistant Layer
reflector
distant EM
N
Eye
R
Ray bounces more times off reflectorRay bounces more times off reflector
Distant LayerDistant Layer
reflector
distant EM
N
Eye
R
Ray propagated through reflectorRay propagated through reflector
Local LayerLocal Layer
Local ColorLocal Color Local AlphaLocal Alpha
Fresnel LayerFresnel Layer
Fresnel modulation is generated at run-timeFresnel modulation is generated at run-time
EM InferenceEM Inference
A x = bA x = bUnknown
EM TexelsUnknown
EM TexelsRay-Traced
ImageRay-Traced
ImageHW Filter
CoefficientsHW Filter
Coefficients
HardwareRender
HardwareRender
ScreenScreenEM TextureEM Texture
Inferred EMs per ViewpointInferred EMs per ViewpointDistantDistant Local
ColorLocalColor
Local Alpha Local Alpha
Run-TimeRun-Time•“Over” blending mode to composite local/distant layers
•Fresnel modulation, F, generated on-the-fly per vertex
•Blend between neighboring viewpoint EMs
•Teapot object requires 5 texture map accesses:2 EMs (local/distant layers) at each of2 viewpoints (for smooth interpolation) and1 1D Fresnel map (for better polynomial interpolation)
•“Over” blending mode to composite local/distant layers
•Fresnel modulation, F, generated on-the-fly per vertex
•Blend between neighboring viewpoint EMs
•Teapot object requires 5 texture map accesses:2 EMs (local/distant layers) at each of2 viewpoints (for smooth interpolation) and1 1D Fresnel map (for better polynomial interpolation)
Frgbrgb DLLL )1( Frgbrgb DLLL )1(
Video ResultsVideo Results
•Experimental setup•1D view space•1˚ separation between views•100 sampled viewpoints
•Experimental setup•1D view space•1˚ separation between views•100 sampled viewpoints
Layered PEM vs. Infinite Sphere PEM
Layered PEM vs. Infinite Sphere PEM
Real-time DemoReal-time Demo
SummarySummary•Parameterized Environment Maps
•Layered•Parameterized by viewpoint•Inferred to match ray-traced imagery
•Accounts for environment’s•Geometry•View-dependent shading
•Mirror-like, local reflections
•Hardware-accelerated display
•Parameterized Environment Maps•Layered•Parameterized by viewpoint•Inferred to match ray-traced imagery
•Accounts for environment’s•Geometry•View-dependent shading
•Mirror-like, local reflections
•Hardware-accelerated display
Future WorkFuture Work
•Placement/partitioning of multiple environment shells
•Automatic selection of EM geometry
•Incomplete imaging of environment “off the manifold”
•Refractive objects
•Glossy surfaces
•Placement/partitioning of multiple environment shells
•Automatic selection of EM geometry
•Incomplete imaging of environment “off the manifold”
•Refractive objects
•Glossy surfaces
QuestionsQuestions
Timing ResultsTiming Results On the
ManifoldOn the
ManifoldOff the
ManifoldOff the
Manifold
22 33
texgen timetexgen time 35ms35ms 35ms35ms
frame timeframe time 45ms45ms 57ms57ms
FPSFPS 2222 17.517.5
#geometry passes
#geometry passes
Texel Impulse ResponseTexel Impulse Response
To measure the hardware impulse response, render with a single texel set to 1.To measure the hardware impulse response, render with a single texel set to 1.
HardwareRender
HardwareRender
ScreenScreenTextureTexture
Single Texel ResponseSingle Texel Response
0
1
1
1
k
s
H s
s
0
1
1
1
k
s
H s
s
Model for Single TexelModel for Single Texel
0 0
1 1
1 1
1
k k
s s
s s
s s
x bA
0 0
1 1
1 1
1
k k
s s
s s
s s
x bA
one column per texelone column per texel
one row per screen pixelone row per screen pixel
Model for MIPMAPsModel for MIPMAPs00,00,0
00,10
1, 1
10,0
1
1, 12 2
1, 1
filter coefficients for levelfilter coefficients for
level
filter coefficients for
u v
u v
m n
Axs
sx
x
x
s
1 1
0,0
0,1
1
10,0
-11
1, 12 2 1, 1
level
l l
l
llu v
m n
xb
s
s
x
xs
00,00,0
00,10
1, 1
10,0
1
1, 12 2
1, 1
filter coefficients for levelfilter coefficients for
level
filter coefficients for
u v
u v
m n
Axs
sx
x
x
s
1 1
0,0
0,1
1
10,0
-11
1, 12 2 1, 1
level
l l
l
llu v
m n
xb
s
s
x
xs
ConclusionConclusion
PEMs provide: •faithful approximation to ray-traced
images at pre-rendered viewpoint samples
•plausible movement away from those samplesusing real-time graphics hardware
PEMs provide: •faithful approximation to ray-traced
images at pre-rendered viewpoint samples
•plausible movement away from those samplesusing real-time graphics hardware
PEM vs. Static EMPEM vs. Static EM
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