Creating Animations for Presentations and the web

Elsewhere on this web site, I discuss how to create presentations and embed movies in PDF files; one question that comes up in both context is: how do you create animated content? One can classify animations by the same two main categories that apply to images: bitmap versus vector graphics.

Bitmap movies

The easiest and most platform-independent way of delivering animations is probably still the GIF89 movie. Other formats that are quite common are .mpeg, .mov etc. I'll talk about other formats later. GIF animations are frame based, so the first thing one needs, of course, is a way to produce the individual frames as bitmap images. They should preferrably be of the same dimensions (although that isn't strictly necessary in the method described below). Assuming you have the images, they should be named sequentially so that they appear in your folder listing in the order in which they are to be incorporated into the movie. Then, we have the following options to create a movie:

• ImageMagick

  ImageMagick is practically a platform-independent tool, because you can get it for Mac, Windows and UNIX. Use the convert command to create a single GIF image. Input files can be, e.g.: PNG, JPG, GIF, BMP, or any other that the program can import. An example command with PNG input would be

  convert -delay 0 -colorspace GRAY -colors 16 -dispose 1 -loop 0 -scale 50% *.png Output.gif
  

  On a Mac, you can get ImageMagick for X11 from fink. See also my general installation instructions.

• GraphicConverter

  There are two simple ways of creating animations with GraphicConverter, the powerful graphics editor bundled with OS X. One leads to a GIF89 file, the other to a Quicktime movie:

  1. Choose File ⇒ Convert&Modify .... Follow the instructions in Chapter 9 of the GC Help document.
  2. Choose File ⇒ Export Slide Show to Movie .... You'll have to navigate to the folder containing the images. After choosing some settings, GraphicConverter will create a file with the extension .mov. This file format is suitable for inclusion in Keynote, for example.
• Other routes

  Here are some other alternatives for creating bitmap-based frame animations:

  1. To convert from Quicktime .mov to .mpeg, one can use QT amateur, a free movie player for Mac OS X which can export various movie and image file formats (even in batch mode). It requires Quicktime 7 to be installed on your machine.
  2. Apple's Quicktime Pro application has more flexibility but it's not free.
  3. If you are comfortable with command-line UNIX tools, there are the free packages mpeg2vidcodec or mpegencode, available for Mac from the porting system fink.
  4. Depending on your installation of imagemagick, the above mpeg encoding can also be done by simply calling convert -quality 100 *.png Outputfile.mpeg
  5. Many mathematical software packages like Mathematica and Maple are able to create image sequences that can be exported as animations. However, I usually want more flexibility and therefore export the individual frame images from those programs, followed by movie conversion using one of the tools mentioned above.

Vector animations

Vector formats are especially practical when you're interested in objects that can be described efficiently using strokes, fills, gradients using only a few control points. The main formats for vector-based movies on the web are SWF (Flash) and SVG (Scalable Vector Graphics). If you have Adobe Illustrator, both of these file formats can be created quite easily. Here is an example I created by drawing a mere four shapes and telling Illustrator to calculate a blend between them:

With these interpolation capabilites, Illustrator is very useful for creating hand-drawn animations.

All you need to know is how to blend your key sketches together and make a movie sequence out of the intermediate steps: The Make Blend command in Illustrator creates a compound object that needs to be disassembled by choosing Expand from the Object menu. This creates a number of objects that may still have to be ungrouped, and each of these then represents one frame in your animation. The next step is to place all these objects into one otherwise empty layer, select that layer in the Layers palette, and choose Release to layers. This creates a sequence of new layers, one for each animation frame. Finally, choose File ⇒ Export for Web and select SWF as the file format. The option Layers to SWF makes the SWF into a movie.

The file size of the Flash animation above (8 kB) is still significantly smaller than even the reduced-size GIF movie shown below (36 kB):

Interactive vector animations

With Flash, one has a format that allows much more than movie playback. The Flash Player engine is used for internet games and user interfaces.

Here's a piece of art called "Don't Stick":

It was created using Flash and ActionScript 3 by my son James Nöckel (December 24, 2007). Try to keep the vehicle from touching the walls by steering with the arrow keys. If you manage to get to a double-digit score, you're a master.

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Jens Nöckel <noeckel@uoregon.edu>

Last modified: Wed Jan 2 12:43:14 PST 2008