Assignment 4 - Architecture and Interiors

Kneeling figure, Humayun's Tomb. Photo by Marc Levoy.

Motivation

Good photography often shows us the familiar in an unfamiliar way. Taking macro photographs last week, we made small things larger on our computer screens, and saw a level of detail not usually visible to the naked eye. For this reason, it's not too difficult to take a macro photograph that makes a non-photographer gasp. Capturing a compelling image of architecture can be much harder. This week you'll be looking at the spaces where people live and work and trying to fit them into a frame.

Architecture is typically more geometric than natural scenes, so this week is a good week to think about the geometry of your scene. Consider repeating elements, size relationships as they change under perspective, the lines induced by vanishing points, and the texture and weathering of man-made objects. One way to surprise people with architecture and interior photography is by using clever composition to highlight the geometric aspects of structures that are subliminal or even overlooked. The requirements this week will help you play with geometry and think about the practical concerns of people who need to represent an interior space in a photograph.

By now you should have a good handle on the controls of your camera, so put your extra effort this week into making your photos visually compelling. Go beyond simply meeting the letter of the requirements and try out some of the rules of composition that were discussed in lecture last week.

Instructions

There are five requirements in this assignment that you should meet by taking 5-10 photographs.

• 1. Requirement 1: Vertical vanishing point. In at least one of your photos, vertical lines in the world (e.g. corners of buildings) must visibly converge to a vanishing point either within or nearly within your frame. To do this, look up and use a wide field of view (a short focal length).

  2. Requirement 2: No vertical vanishing point. In at least one of your photos, vertical lines in the world must appear parallel in your photograph. You can do this by looking straight ahead when you take the picture and fixing the composition by cropping later. Alternatively, as demonstrated in lecture, you can use Photoshop's perspective warp tool (found under Edit->Transform->Perspective) to make these lines parallel. You can also use the lens correction tool found in the Filter->Distort menu.

  3. Requirement 3: Frame your shot. At least one of your photos should be shot through a door, window, archway, or other physical man-made frame. The frame should be visible in the photograph, but is not necessarily the subject. The frame need not be rectangular.

  4. Requirement 4: Repeating patterns. Find some interesting repeating patterns in a building or other man-made architectural object and use them as the focus of a photograph. Try to be creative here -- don't just take a random photo that happens to have some repeating elements. Instead, make the repeating elements the obvious theme of the image. So while you should certainly explain your choices in your comments, the repeating patterns shouldn't be so obscure that the viewer would need to read your comments in order to ascertain the repeating theme of the photo.

  5. Requirement 5: Interior Panorama. As real-estate agents know, it's hard to capture the interior of a room without making it look small, and it's usually impossible to fit the entire room in the frame (where would you stand?). We're going to solve this with an interior panorama. Stand in the corner of a small room, or at the center of a large room, and take a sequence of photographs that captures the entire room, rotating the camera about its center of perspective (somewhere in the middle of the lens). Make sure your photographs overlap by about 25-50%. Then, convert your set of photographs into a single panorama that better shows off the interior of the room. We want to see the panorama, not the source photographs. Try to find an interesting room to do this in. Interiors are often dim, so pay attention to your camera settings and the available light.

     1. Note: Some cameras have a mode for automatic panoramas. You should not be using the automatic mode for the purposes of this requirement. We would like you to stitch the panorama yourself.

     2. In Photoshop you can make a panorama by going to the File menu, selecting Automate, and then Photomerge. A cylindrical layout usually works best, but you should try the other ones too to see what they do. If the resulting image has obvious artifacts (eg edges that don't line up), you probably didn't rotate the camera about the center of perspective, and need to try again. For this reason, you may want to make multiple attempts at capturing the source photos for the panorama before you take your photos back to Photoshop.

     3. You can also use some other panorama stitching tool, such as autostitch, if you like.

Upload your photos and add comments.

As before, upload your photos to Google Photos as an album, caption the photos, and post the photos to the course's Google+ community as explained in Assignment #1, giving your post a title, like "Submission of assignment #4 (Architecture and Interiors) by <my name>" (substituting your name).

Example Solution

As usual, we've post an example solution to this assignment to let you know what we expect.

Peer Grading

You should follow the same rubric as the previous 3 assignments.

Practice problems

Finally, here are some practice technical problems related to recent material. You do not turn these in; they're just for your educational benefit. The correct answers will be revealed here in bold after the assignment deadline

• • Problem 1. If sampling an image or scene leads to aliasing, what could you do to get rid of it (check all the apply):

    • • a) Downsample the image in Photoshop

• • • b) Pre-filter the light before it reaches the sensor

      • c) Blur the image in Photoshop

      • d) Upsample the image in Photoshop

      • e) Nothing

• • Problem 2. According to sampling theory, what should be your minimum sampling frequency, when trying to record a signal with maximum frequency 'f', to avoid aliasing?

    • • a) sqrt(f)

      • b) f

      • c) f^2

      • d) f/2

• • • e) 2f

• • Problem 3. An image convolved by the following kernel will (circle all that apply):

• • • 0 0 0

    • 0 0 2

    • 0 0 0

    • a) be shifted

      • b) become more blurred

      • c) become sharper

    • d) become brighter

• • Problem 4. This question is not directly related to this week's material, but is meant to show you what the third type of question on exams - short answer questions - look like. You have purchased a 100mm lens and you are eager to see how well it performs as a close-up lens for macro photography. After reading the specifications online, you learn that the maximum image distance (between the sensor and the equivalent thin lens) is 120mm.

• 100mm

  • (a) For this lens, what is the distance between the equivalent thin lens and the sensor when the camera is focused at infinity?

  • (b) Given it's maximum image distance, what is the closest object distance that will produce an in-focus image?

• 600mm. The maximum image distance (s_i) is given as 120mm and the focal length is given as 100mm. Using the Gaussian lens formula (1/s_i+1/s_o = 1/f), we compute that the object distance (s_o) is 600mm. From this, we can conclude that this telephoto lens cannot focus any closer than 0.6 meters.

Due Date

Assignment Deadline: 11:59pm, Sunday, April 17, 2016

Commenting Deadline: EOD, Friday, April 24, 2016

Page authors: Marc Levoy, Andrew Adams, and Jesse Levinson, revised by Marc Levoy for the Google version of this course.