3D models

We will describe in this article some useful tips for a better use of three-dimensional animation with respect to the final presentation format, whether video, cinema or electronic media. For this purpose we will divide this article into two main aspects: a first set of technical considerations, and finally, a series of conceptual recommendations.

First of all, it is necessary to determine what is the target format for our 3D animation: Will it be shown on video? In cinema? On DVD? In Multimedia? Each of these formats has its own resolution and image size, and it is of the first order to take into account this information at the time of performing not only the final rendering process (which as we have already seen, is nothing more than the "drawing" that the computer makes of each of the frames of the animation), it also involves the initial design of the objects to be animated and the very planning of the movements.

The format of the image is determined by the window of the camera(s) we use. In any case, if we use more than one camera for our animation, it is important that the images of all of them are processed at the same size and resolution. The most commonly used formats, sizes and resolutions for the different media named above are as follows:

Video / Television:

The NTSC format generally features a ratio of 4 units wide to 3 high. The most appropriate pixel size of the image (one pixel is the minimum metric unit used in computer graphics), should be 640 x 480, or 648 x 486 pixels: this second size offers slightly better definition. The resolution of the render of the final image will never be greater than 72 pixels per inch, because a higher resolution is not only not perceived by the human eye, but would also create, unnecessarily, longer render times and a greater space occupied on the hard disk for the final film.

The image format in the PAL standard keeps a similar proportion to the previous one, and the most used image size for the format is 720 x 576. Likewise, the final resolution of the image will be 72 dpi ("dots per inch").

The most commonly used 3D format for cinema and DVD is the ratio 16 to 9. In the case of cinema, due to the different nature of the support in relation to video (it is well known that cinema uses film and photochemical processes, while the video is stored in an electromagnetic medium), it is important here to know that we need a greater definition of the image. In simpler terms, to make 3D animations for cinema we need more pixels that can give us a greater amount of information and sharpness to the image. In this case, the correct size would be 1920 x 1080 pixels, at 72 dpi.

In the case of the DVD, the size can be smaller: 1280 x 720 pixels are the appropriate measurements of the image.

The most commonly used size in the production of 3D animations for CD ROM and Web is 320 x 240 (4:3 ratio). However, with the relatively recent introduction of the MPEG video compressor, it is possible to make full-screen size videos that run perfectly on any of the users' monitors. For this case, it is necessary to render the animation in a size not less than 640 x 480 pixels, also at 72 dpi resolution.

• Colour

If the final animation is intended for the video medium, it is necessary to use safe colors for broadcast, as in any type of digital edition. Excessively bright colors can, apparently, be perceived very well on our computer monitor, but on a normal TV they could appear "burst" producing the classic flicker effect. However, color problems can be easily solved when it comes to digital assembly: almost all current software packages for non-linear editing (Media 100, Premiere, AVID, etc.), have useful filters to attenuate the excessive brightness of colors out of range. By simply applying one of these filters to our final film we can obtain safe colors for broadcast.

In the case of Cinema, DVD and Multimedia, it is important to maintain control over color, although this issue is not as critical as in the case of video. However, for animations that are going to be distributed through any electronic medium, it is key to know that the animations must be processed initially to millions of colors (24 bits or more of color depth) to ensure the highest possible chromatic quality.

• Compression

There are essentially two final output formats: QuickTime and AVI, the former being not only the precursor to digital video, but generally offering higher final quality in compression options. An ideal (if not almost utopian) render would be one that does not use any compression on the image. However, it is clear that this option requires gigantic sizes on hard drives, which is not always available to all 3D filmmakers. For QuickTime format, the Animation compressor is perhaps the one that least affects the final quality of the image, at a reasonable cost, in terms of hard disk space. In the case of the AVI format, the BMP compressor is the most suitable if you want to preserve the quality of the image as much as possible.

Either way, it should be noted here that hardware tools for editing (especially video output and input cards) always have their own particular image compressors. Such compression formats are optimized for the best performance of the video. It is important, therefore, to be documented with the corresponding software manuals for each type of manufacturer, and if possible, to carry out the final processing of the animation with these parameters.

• Frames per second

The number of frames per second (frame rate) of the animation is also necessarily determined by the type of output format we choose. NTSC video for television, like the DVD format, has a frame rate of 29.97 frames per second (fps), while PAL video has a rate of 25 fps. Films created for cinema must be made at 24 frames per second. Finally, animations created for CD-ROM or for the Web often use a rate of 15 to 20 frames per second.

Beyond the output medium used, 3D animation constitutes, rather than a technique, a complete language in itself. It is therefore convenient to study this language through the continuous observation of three-dimensional realizations, whether complete stories or simple animations of a corporate type. The important thing here, in any case and regardless of the technical resources we have at our disposal, is creativity.

1. You are the director.
"Lights, camera and action" is perhaps the common expression most associated with film directors, but especially in the 3D realm, it takes on special importance. You have at your disposal the objects that you believe you can modify in appearance and movements, you can illuminate them as you want and you can even make shots from perspectives that would be impossible in reality. Take advantage of these resources and their infinite combinations. Think first of all that 3D is a narrative medium, like film, video, writing or music. You can create, for example, a complex narrative from the same object moving, but captured consecutively by different cameras. Or you can generate the feeling of different times of the day by simply varying the lighting.
2. Less is more.
One of the most frequent mistakes to which 3D filmmakers are driven is to saturate their realizations with the greatest amount of effects, perhaps with the aim of achieving spectacularity in their results. However, it should be noted here that the more effects we use, not only do the rendering times increase, but we seriously run the risk of creating a saturated, gimmicky and unclear product for viewers. When we use too many effects, they tend to produce the opposite effect: instead of being highlighted, they end up visually nullifying. Use the effects carefully, and keep in mind that these should always obey a clear and determined visual concept, not a simple whim. For example, it is not convenient to use a motion blur effect in an entire film, but this type of filter is more appropriate and more effective for those passages where we want to highlight the speed of an object.
3. Surprise the viewer.
Always think about what you, as a viewer, would like to see in the 3D animation you are making, but also think about the kind of things the viewer never expects: an untimely camera turn, a sharp movement in a slow sequence, a change of lighting at a certain time can be crucial to solving an animation. But as with the effects, do not abuse them, as drastic and very successive changes can be distracting and inefficient. Always look to plan your animations through a StoryBoard, but do not use it as if it were a straitjacket: many times, during the development of the animation, you will find that the ideas you had at the beginning are susceptible to be improved... and if this is the case, then go ahead!
4. Model, model, model... and illuminate.
Achieving mastery in 3D is a matter of practice and time, just like any discipline. Start by making simple models, basic geometric shapes like a ball or a box of matches. To the extent that you achieve these models well with the appropriate textures, gradually seek to make more complex and articulated figures. You will find that objects can often be summarized as the combination of geometric figures, and likewise the very structure of the objects will suggest the type of movements you can create for them.

It is also important that you experiment with the illumination of the object: not only is it enough to have good textures, but the realistic appearance of the figures is produced by light. It is often advisable to have at least 3 points of light with different intensities, apart from ambient lighting. If necessary, a good tip is to create, initially, the models in plasticine (not necessarily textured), and study the way light influences their appearance.

If you achieve a remarkable development in these two aspects, you will have solved 75% of the 3D techniques.

5. Keep track of the process of your work.
Apart from the StoryBoard, it is convenient to make continuous renders of your animation. It is preferable to do small-sized processes as a test for an effect, a movement or a space, rather than finishing the animation and making the final render in one go. It is easier to make corrections "on the fly" of the project, and not at the end of it. If possible, store the most important ones, as these films serve as a "sketchbook" that will allow you to gradually compare the progress in your project.