Assignment 3: Camera Simulation

Due: Friday May 8th, 11:59PM

Please add a link to your final writeup on Assignment3Writeups.

lenses

Description

Many rendering systems approximate the light arriving on a virtual camera's film plane by assuming the camera is a pin-hole camera. In contrast, real cameras contain multi-lens assemblies with different imaging characteristics such as limited depth of field, field distortion, vignetting and spatially varying exposure. In this assignment, you'll extend pbrt with support for a more realistic camera model that accurately simulates these effects.

Specifically, we will provide you with data describing real wide-angle, normal and telephoto lenses, each composed of multiple lens elements. You will build a camera plugin for pbrt that simulates the traversal of light through these lens assemblies. With this camera simulator, you'll explore the effects of focus, aperture and exposure. Once you have a working camera simulator, you will add simple auto-focus capabilities to your camera.

Step 1: Background Reading

Before beginning this assignment you should read the paper "A Realistic Camera Model for Computer Graphics" by Kolb, Mitchell, and Hanrahan. This paper is one of the assigned course readings.

Step 2: Getting Up and Running

Starter code and data files for Assignment 3 are located at http://graphics.stanford.edu/courses/cs348b-07/assignment3/assignment3.zip.

Step 3: Setup the Camera

The .dat files included with the starter code describe camera lenses using the format described in lecture. In pbrt, the viewing direction is the positive z-direction in camera space. Therefore, your camera should be looking directly down the z-axis. The front of the first lens element (the lens element closest to the world, and farthest from the film plane) should be located at the origin in camera space with the rest of the lens system and film plane extending in the negative-z direction.

Each line in the file contains the following information about one spherical lens interface.

lens_radius  z-axis_intercept  index_of_refraction  aperture

More precisely:

lens_radius: is the spherical radius of the element.
z_axis_intercept: is thickness of the element. That is, it's the distance along the z-axis (in the negative direction) that seperates this element from the next.
index of refraction: is the index of refraction on the camera side of the interface.
aperture: is the aperture of the interface (rays that hit the interface farther than this distance from the origin don't make it through the lens element)

Note that exactly one of the lines in the data file will have lens_radius = 0. This is the aperture stop of the camera. It's maximum size is given by the aperture value on this line. It's actual size is specified as a parameter to the realistic camera via the pbrt scene file. Also note that the index of refraction of the world side of the first lens element is 1 (it's air).

Step N: Submission

We've created wiki pages (FirstnameLastname/Assignment3) for all students in the class. Access to these pages is set up so that only you can view your page. Please compose your writeup on this page and link to it from the Assignment3Writeups page.
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Grading

This assignment will be graded on a 4 point scale:

1 point:
2 points:
3 points:
4 points:

Assignment3