Collecting good face pictures

From Vision Wiki
Jump to navigation Jump to search

Subjects

Collecting peoples' pictures falls under the `human subjects' category, even if the pictures are going to be anonymized. (a) The subjects need to be informed as to the purpose of the experiment and (b) you need to understand the privacy implications (Andrea can point you to the human subjects' UCLA web site).

Efficient operation

If you are planning to roam around campus collecting the pictures, you need a crew of at least 2 but better 3 people. One has the camera and shoots the pictures, the other 1-2 select subjects, show them the info flyer, obtain consent, and shepherd them towards the photographer.

Equipment

Ideally a reflex camera with a ~85mm equivalent lens (on the Canon D60 you multiply the nominal focal length by 1.3 to obtain the real focal length). A 28-135 zoom lens will do well. Set it on the correct focal length.

Better to carry extra batteries with you. If you run out of batteries in the middle of the shoot you will loose momentum.

Site

Indirect diffuse light is easiest. Avoid: (a) bright single-direction light (harsh shadows), (b) back light, (c) dappled light. Try for the North side of buildings. Make sure the subjects do not have to stare into a bright field: they will instinctively squint and grimace. If you set yourselves up with a uniform blue background you will get better pictures, and easier to segment automatically if needed. Andrea has a piece of blue cardboard I use for this.

Camera settings

Use 1/30' of a second, or faster, to avoid motion blur. Choose the metering option that focusses and measures light using the center of the frame. Try to use low ISO settings (100 or up to 400) to avoid grainy pictures. Practice a bit ahead of the photo-shoot to make sure you know what you are doing.