A simple pinhole projector for viewing a partial eclipse. Image courtesy of NASA.

Project 0: Optional Eclipse Viewing
CS 4476 / 6476: Computer Vision

Brief

Overview

The 2017 Eclipse on Monday, August 21st is the first total eclipse in the United States mainland in nearly 40 years. We are lucky to be near the path of "totality". From our campus in Atlanta the Sun will be 97% eclipsed and a short drive to the north, cutting through Tennessee, Northeast Georgia, and the Carolinas, is the path of totality. We will use the eclipse as an opportunity to learn about pinhole cameras. To facilitate your eclipse viewing, there will be no lecture on Monday, August 21st. To view a total eclipse (highly recommended) you will have to drive at least 2 hours from campus which would not be possible with our lecture time.

A two minute video for learning more about which eclipse phenomena to keep an eye out for can be found from Smarter Every Day. A longer video from the same channel is here.

Details

While many people are scrambling to find eclipse glasses to view the Sun during partial eclipse (don't look at the Sun without them!), the experience might be a bit underwhelming. The Sun's apparant size from Earth is, after all, pretty small. The Sun's angular diameter from the Earth is only half a degree. So one interesting alternative to viewing the Sun directly is to view the projections of the Sun that are created by pinholes, either manmade or natural. These projections can be made arbitrarily large and are inherently safe to view because they are no brighter than the Sun's typical reflections.

In lecture, we will learn about the pinhole camera model and the eclipse is a great opportunity to demonstrate a simple pinhole camera. See this guide or this guide (both from NASA) on the construction of pinhole eclipse viewers. Of course, these pinhole viewers work perfectly well to view the Sun without an eclipse, but only with an eclipse does it become obvious that the pinhole is projecting an image of the Sun rather than a simple blurry circle. In fact, the eclipse shows us that there are many natural pinhole projectors in our world (e.g. trees).

You can find many instructions online for building more sophisticated eclipse viewers, e.g. this guide from Cody's Lab. Be very careful if go this route as you will be looking directly at the sun (although through a pinhole and through a projection screen) so the pinhole must be tiny. Another guide on more sophisticated pinhole projectors is this guide from the American Astronomical Society.

There are numerous other interesting imaging opportunities in an eclipse. You can try to directly image the eclipse with zoom cameras, but again this is only safe for your eyes and the camera with proper filters.

If you do manage to capture interesting images with a pinhole camera, consider handing them in through t-square so they can be highlighted in class.

Rubric


Web-Publishing Results

All the results for each project will be put on the course website so that the students can see each other's results. The professor and TAs will select impressive projects to highligh in class and on the course website. If you do not want your results published to the web, you can choose to opt out. If you want to opt out email the lead TA for an assignment.


Handing in

Most projects have strict handin instructions to facilitate grading. For this one, we will be less strict. You can turn in nothing at all (this project is optional!), or you can turn in through t-square any single file. For example, a photo showing off what you've done, a pdf or webpage describing your experiments, or a readme file with a link to a Youtube video.

Hand in through t-square.gatech.edu.

Credits

Assignment developed by James Hays.