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Environment Mapping

Overview

Overview

Introduction

Overview

Overview

Cube mapping

Cube mapping construction

Cube mapping

Sphere mapping

Acquisition using camera

Acquisition using camera

Acquisition using camera

Acquisition using camera

Sphere mapping

Overview

Overview

Rendering distant
geometry (“environment”)

Efficient (but
approximate) reflections

Limitations

Limitations

Limitations

End of slide show, click to exit.

Environment Mapping

Overview

Introduction

Environment map construction

sphere mapping

cube mapping, …

Environment mapping
applications

distant geometry

reflections

bump mapping

Overview

Introduction

Environment map construction

sphere mapping

cube mapping, …

Environment mapping
applications

distant geometry

reflections

bump mapping

Introduction

Environment map

an image with a large FOV: panorama

a collection of rays that pass
through one point

it could cover all possible
view directions

several types, according to how
the rays sample the solid angle

Applications

distant geometry

fast (approximate) reflections

bump mapping

Overview

Introduction

Environment map construction

spheric mapping

cube mapping, …

Environment mapping
applications

distant geometry

reflections

bump mapping

Overview

Introduction

Environment map construction

sphere mapping

cube mapping, …

Environment mapping
applications

distant geometry

reflections

bump mapping

Cube mapping

Cube mapping construction

By rendering

render scene for each of the 6
faces

Acquisition using camera

take overlapping pictures by
rotating camera around COP (construction images)

undistort each construction
image

register images in common
coordinate system

build cube map

for every pixel of every face
(“for each ray in the panorama”)

project on each construction
image

blend colors from all
construction images that had the current ray

Cube mapping

Simple math for construction
and lookup

Fairly uniform sampling

6 separate images that need to
be acquired, stored and processed

Sphere mapping

The image of a small shiny
sphere seen from far away

Incoming rays are parallel

Covers all directions

Sampling varies considerably

Acquisition using camera

Acquisition using camera

Acquisition using camera

Acquisition using camera

Sphere mapping

More expensive math for
construction and lookup

Non-uniform sampling

Can be acquired with one photo
but

camera visible in the map

light probe does not float in
mid air

Overview

Introduction

Environment map construction

sphere mapping

cube mapping, …

Environment mapping
applications

distant geometry

reflections

bump mapping

Overview

Introduction

Environment map construction

sphere mapping

cube mapping, …

Environment mapping
applications

distant geometry

reflections

bump mapping

Rendering distant
geometry (“environment”)

Environment map stores distant
geometry as seen from the center of the scene (EM)

clouds, mountains, moon, stars,
sun etc.

Instead of clearing the frame
buffer, set it to the appropriate part of the environment

look up each desired ray in the
env. map as if the environment map was taken from the current position of the
camera (D)

assumption valid because
distance to environment much greater than distance from center of scene (EM)
to current position (D)

Efficient (but
approximate) reflections

Acquire (render or capture) the
environment map from the center C of the reflector

Run time algorithm

if scene changed re-render
environment map

for each reflector

for each triangle

for each visible inside pixel

compute normal (n)

compute eye vector (e)

compute reflected ray (r)

look it up in the env. map (r)

Limitations

Incorrect reflections

A instead of B

No motion parallax

No inter-reflections

No multiple reflections

Limitations

Incorrect reflections

No motion parallax

rendered image always: C, B, A

correct: C, A (B hidden)

correct (not shown): B, C, A

No inter-reflections

No multiple reflections

Limitations

Incorrect reflections

No motion parallax

No inter-reflections

No multiple reflections

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Second level

Third level

Fourth level

Fifth level

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Overview

•

Introduction

•

Environment map construction

–

sphere mapping

–

cube mapping, …

•

Environment mapping applications

–

distant geometry

–

reflections

–

bump mapping

Overview

•

Introduction

•

Environment map construction

–

sphere mapping

–

cube mapping, …

•

Environment mapping applications

–

distant geometry

–

reflections

–

bump mapping