3D Depth Cues
Sunday October 30th 2011, 11:31 am
Filed under: Concepts

Monocular
1. Motion parallax: distant things move slower; close things move faster.
2. Depth in motion: something coming closer to you gets bigger.
3. Perspective: parallel lines converge as they move away from you.
4. Familiar size: evaluating the position of an object whose size is known.
5. Relative size: comparing the position of an unknown object to one whose size is known.
6. Color and contrast: all else being equal, reds appear closer than blues, and high-contrast colors appear closer than low-contrast colors.
7. Accommodation: whether the eye is focused on a near or far object, as reported by our eye muscles.
8. Occlusion: an object blocking something else is assumed to be in front of it.
9. Depth of field: blurrier objects are assumed to be further away.

Binocular
10. Stereopsis: the difference between the views of the left and right eye.
11. Convergence: the angle from our eyes to the object viewed, as reported by our eye muscles (for objects closer than ~10m).

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OBJ Batch Export
Saturday October 22nd 2011, 7:34 am
Filed under: Maya

Here’s how to export a sequence of frames from Maya as individual OBJ files:

Step 1. Download this OBJ Exporter MEL script.

Step 2. In Maya, go to Window / Settings/Preferences / Shelf Editor to add the script as a button.

Step 3. Click the New Item icon to create a new blank button.

Step 4. Click the Icon Name icon to add a custom image for your button (included with the download).

Step 5. Go to the Command tab and copy-paste the script in. Make sure the radio button is set to MEL, the language the script is written in.

Step 6. Click Save All Shelves.

Step 7. The new button should now appear in your shelf. Click it…

Step 8. …to open the OBJ batch export panel.

An OBJ sequence is a great way to do replacement animation with 3D printouts:

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Format Suggestions
Tuesday October 04th 2011, 7:06 pm
Filed under: Concepts

1. Archival master: This is the copy you file away forever, in the highest quality available, and in an “open” format that you can be reasonably sure will be available many years into the future. (That is, it’s open-source, or the patent’s expired). Usually a format meeting these requirements can’t be played back easily, or at all–it’s just for storage.

Recommendations:

  • picture:  1920×1080 @ 12fps, 23.976fps, or 24fps.
  • sound:   48KHz 24-bit, stereo or discrete 5.1
  • codecs:  EXR image sequence (32bpc) or PNG image sequence (16bpc or 8bpc); uncompressed AIFF or WAV files.

2. Submaster: This is the copy you make from the master and work with day-to-day. It’s slightly smaller and lower-quality than the master, and usually in a proprietary format that might be gone in five years, but works great for now. (A high-quality HD video that still plays back adequately on an older computer is a relatively recent invention.) You can also use the submaster to make DVD and Blu-ray discs if you need to.

Recommendations:

  • picture:  1920×1080 @ 23.976fps or 24fps.
  • sound:   48KHz 16-bit, stereo or discrete 5.1
  • codecs:  Quicktime with Apple ProRes, GoPro Cineform, Avid DNxHR, or PhotoJPEG codec; PCM audio.
  • note: Quicktime DV is still a popular choice for SD material, but be aware that —unlike DVD discs—the DV tape standard only supported NTSC and PAL frame rates. 24p DV tape hardware used hacky workarounds specific to the manufacturer, so if you’re working with some legacy material I would transcode it all into a modern codec.

3. Distribution copies: These are the copies you make from the submaster and hand out to your audience. They’re much smaller and lower-quality than the submaster, but can be easily passed around and viewed on many devices.

Recommendations:

  • picture:  1920×1080@ 23.976fps or 24fps.
  • sound:   48KHz 16-bit, stereo or discrete 5.1.
  • codecs:  H.264 MP4 video; AAC or AC3 audio.
  • note:H.264 is currently the established standard for distribution, but IP-rights squabbles in the past (now largely resolved) kept it out of certain free-software projects, like the Chromium browser. This doesn’t affect you in most common situations, but it may be worth making a distribution copy in the fully open WebM format as a hedge.
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