Image Synthesis Assignment 3: Realistic Camera Simulation

Due: March 1

lensview.zip (contains src and bins for the lensview program)

realistic.zip (contains src and prebuilt windows binaries for camera simulator)

Description

Many rendering systems approximate irradiance on the film plane by sampling the scene through an infinitesimal aperture (i.e a pin-hole). However, this technique fails to capture important imaging characteristics of multi-lens cameras such as depth of field, distortion, vignetting and spatially varying exposure. In this assignment, you will implement a realistic camera model capable of capturing these effects. Specifically, your camera model will simulate the traversal of light rays through complex lens assemblies as shown above. This assignment is divided into the following parts:

• Build a camera simulator that loads lens specification files, computes values such as focal length, principle plane locations, etc., and traces rays through the lens elements. We provide an OpenGL framework you can use to visualize the lens system and report your simulation results.

• Using your simulator, build a realistic camera plugin for pbrt and use it to explore the imaging characteristics of several lens types including telephoto, wide angle, and fisheye. We provide skeleton code for the camera plugin with clearly defined input parameters.

Step 1

Read the paper A Realistic Camera Model for Computer graphics, which describes in detail the algorithms you will need to implement. You should be comfortable with the concepts before you attempt to write any code for this assignment. Also, you may want to look over a text on basic lens optics and transformations.

Step 2 (Part 1)

Below is a table listing of the intrinsic properties of the four included lens systems. Note that all values are assumed to be measured in millimeters.

Here are two images per lens system, where the image on the left is the ray-traced solution, and the image on the right is the thick lens approximation. In some instances I choose to highlight the deviation (or lack thereof) between the two methods .

Double Gauss
Fisheye
Telephoto
Wide Angle

Step 3 (Part 2)

This lens system was then used to develop a plugin for pbrt that simulates realistic camera systems. Below are a series of images rendered with the implemented plugin. Note: these images have different exposure settings because some are inherently under/over exposed. Every image uses the lens systems described above. The weighting function associated with each image is not the normal Cos(θ)^4 term, but rather a form factor derived in the accompanying paper.

Double Gauss: Cones	Fisheye: Cones	Telephoto: Cones
Wide Angle : Cones	Double Gauss: Low Sample	Double Gauss: High Sample
Double Gauss: Thick Lens/Low Sample	Double Gauss: Thick Lens/High Sample	Fisheye: High Sample
Double Gauss: Close Focus	Double Gauss: Far Focus	Double Gauss: All in Focus
Telephoto: In Focus	Telephoto: Out of Focus	Double Gauss: Infinite Focal Distance

Accidental Art

Don't just scale your rays by -x, it turns out this doesn't work... DUH Check out my cool point sampling though, yeaaaaaa	Ahh the flipped x axis...	Fuzziness plagued my soul for a good 12 hours until I realized that it was all due to the fact that I never refocused my system after adjusting the fstop