3D Animation is all the rage on the web and is becoming more popular every day. But before you begin to create 3D animations for your web site, you need to consider some basic questions, such as: What is its purpose? What kind of audience do you want to attract? What are you trying to say/promote? Will the animation add interest to your site or detract from it? If you've decided that having a 3D animation will add value and interest to your site, we move onto other considerations, which include file formats and size, along with design and execution.

When looking at the available image and animation formats, here are a few things to keep in mind. JPEG, (Joint Photographic Experts Group) is a 24-bit file format and is the overall best choice for compressing photographs, naturalistic artwork, grayscale images and similar material. As a JPEG file is compressed, it discards data and is referred to as a "lossy" format. Repeated saving discards more data and can cause "artifacts," where portions of the image begin to clump together.

GIF, (Graphic Interchange Format) is the format of choice to compress lettering, simple cartoons, and line drawings. GIF images are often made up of Vector graphics, such as lines and curves, which are mathematically defined, so they produce a high quality result, no matter how much they are scaled, but a GIF is a bitmap format, so the scaling options don't apply. GIF files are often composed of few colors and compress well. Other common animation formats are AVI (Audio-Video Interleaved - a desktop video movie format from Microsoft), MPEG (Moving Picture Experts Group), MOV (Quicktime), SWF (the Flash Player format) and Shockwave.

When using image maps in 3D, file formats to consider are: JPEG and GIF as above, as well as TIFF (Tagged Image Format), TGA (Targa, by Truevision) and PNG (Portable Network Graphics). PNG is worth noting because it offers a 48-bit true color setting and a 16-bit grayscale setting. One advantage is that PNG is lossless, meaning that no matter how many times you save the file, you will not lose data. This is important for maintaining high-quality images. Another factor favoring PNG is gamma correction, a setting used by many image manipulation programs to measure brightness and contrast levels. PNG automatically adjusts the gamma setting and makes sure that images look correct across platforms.

On the down side, PNG files are almost always larger than JPEG images. Another issue involves file size and compression. As an example, let's say you took a 24-bit TIFF file and saved it as both a PNG and a GIF. The GIF format would be smaller due to the fact that PNG uses up to 48 bits of color, whereas GIF uses only eight. The GIF compression scheme discards a lot of data, while PNG almost always saves images in a 24-bit color format. Thus, there is no way the files can compare. Regardless of PNG quality, JPEG is still a better choice for 24-bit color images. PNG files tend to be five to 10 times larger than a standard JPEG file. Other caveats: Don't recompress JPEG files with PNG because artifacting can become a problem. And don't add alpha channels to opaque images because this can create large files unnecessarily.

Below are 10 animation tips designed to help you make clear decisions about animation aesthetics, implementation, storyboarding and optimization, without sacrificing quality. These tips, while aimed at 3D, can also be applied GIF or Flash animations.

1. Before you even begin to create animations, there are several important aesthetic issues to take into account. To elaborate, a single animation on a web page will overwhelm all static images, so placement is important. As mentioned above, make sure that the animation is beneficial to your web site, otherwise you will lose your audience.

2. Before you place a finished animation on your site, be aware that if you have more than one animation on a single page, the effect can overwhelm the viewer and turn them off, rather than draw them in. Also, animations that cycle endlessly can quickly become annoying. Design your animation with a finite number of loops, so that it eventually stops.

3. Once you've decided to create an animated sequence, you need to start with the fundamentals. Of these,
a crucial step is the creation of the storyboard. Here, you detail the animation in a precise fashion with sketches, scripts, transitions, timing, etc. It is with the storyboard that you can work out many creative difficulties. And once you've finished the storyboard, you have, in a sense, created the animation.

4. A key issue in storyboard design is complexity, which was a common problem encountered by many of my animation students. Often, they would design animations that were beautiful in theory, but impossible to complete in the time available. Whenever possible, keep it simple. If necessary, you can always add detail later.

5. When working with polygonal meshes, consider reducing the number of vertices to define the image. As an example, Autodesk Maya makes use of the Polygon Reduction Tool which allows you to decimate the model but retains detail, so the reduced model is as close to the original as possible. This will reduce file sizes and is useful for gamers. If you're using a 2D application to create your shapes (such as Adobe Illustrator the KPT 6 plug-in, these applications offer a command to reduce the number of points in a path. Finally, when placing an animation on your web site, give the viewers an idea of the file size so they can determine if they want to watch it or not. This is especially important for users with slower modems.

6. When working in 3D, reduce geometric complexity for objects that are further away in a scene. At a distance, such detail is not likely to be discernable by the eye.

7. When objects are in motion, the eye is not able to discern information one would normally see in a still image and is much more forgiving. This means that details can be further reduced.

8. In 3D applications, lines and facets can appear on an object that points away from the viewer. Turning these off reduces image complexity and rendering time. Also, turning off anti-aliasing will speed up rendering. The down side is that the edges will appear jagged, but this may not affect your animation.

9. As with vector images, it's important to reduce the number of points and not to rely totally on geometry alone to define create an object. A better option is make use of image maps, which create the illusion of geometry while reducing the file size. One note of caution: be careful how you use image maps, as they can bloat your file sizes as well. Until the bandwidth issue is resolved, keep file sizes as small as possible. This issue becomes even more important when you consider that many users still use 56.6Kbps modems.

10. One method for compressing image maps or bitmaps is "Weighted Optimization," initially available in Photoshop 6/7 and ImageReady 3/7. Weighted Optimization uses an alpha channel to vary compression settings across an image. For areas where quality is important, you use a lower compression, and in areas such as sky, you use a higher compression. The end result is an image of a small size but certain areas are of a high quality. Weighted Optimization gives you control over GIF dithering, lossy GIF settings and JPEG compression.

The above tips will help you make wise decisions about animation aesthetics, implementation, storyboarding and optimization, without sacrificing quality.

© Nathan Segal

Related Articles

·  3D TUTORIAL: Lighting ·  3D TUTORIAL: Modeling for Animation