3D Photometry

2019 Spring

Image Photometry

Slide source: Bob Collins

Image Photometry

Slide source: Bob Collins

Image Photometry

Slide source: Bob Collins

Image Photometry

Slide source: Bob Collins

Image Photometry

Slide source: Bob Collins

Image Photometry

Slide source: Bob Collins

Image Photometry

Slide source: Bob Collins

Image Photometry

Slide source: Bob Collins

Image Photometry

Slide source: Bob Collins

Reflection Model

f f

Perfect

Diffuse

Perfect

Mirror

irradiance

radiancef

Bidirectional Reflectance Distribution Function

: is the ratio of the radiance in the outgoing direction to the incident irradiance.

: defines how light is reflected at an opaque surface.

albedo

Simple BRDF Acquisition using Single Camera and Single Separate Light Source

Camera

Light

Move Camera? or Object?

Phong reflection model

n

soiphong crrf )(cos),(

),( or rrangle

Diffuse

(Lambertian)

Specularity ≒ roughness

Torrance-Sparrow BRDF

A type of microfacets BRDF

ri

FGDf

coscos

Gaussian distribution of a microfacet

Self-occlusion

Fresnel

1. Complex and not practical

2. For graphics rendering, not for detection

Ward BRDF Measured Data based BRDF

)exp(

Af

Single Gaussian distribution

(including occlusion, Fresnel)

Lafortune BRDF

Combines multiple lobs

Image-based BRDF - Marschner BRDF : HDR image - Data-Driven reflectance model : set of physically meaningful BRDF basis : interpolate them