If you have a 3D TV or projector, you may be lamenting about the lack of 3D contents. Time to take things into your own hands! With Tao Presentations, you can create yourself 3D animations on your display, and discover the magic of 3D storytelling. Whether you want to give a new touch to your photo album or show off the growth curve of your startup, 3D can really add a unique touch to your presentations.
There are many ways to display depth on a screen. Tao Presentations supports the large majority of them. This article will discuss the different types of 3D display, their respective benefits, and how to best take advantage of them.
The following video shows a few of the many 3D display modes available in Tao Presentations. In the video, the various modes are selected using the built-in command menu, which you can activate by pressing the Escape key on the keyboard. You can also select the display mode with the View menu entry. The presentation being shown can be dowloaded directly in Tao Presentations, and is discussed here.
The first thing to consider is the display technology at your disposal. The main techniques to display in 3D are:
Choosing the right display technology is difficult, and depends on the application and usage context. Do not hesitate to contact us for information.
A passive 3D TV screen will send half of the scanlines to the left eye, half to the right eye. An active 3D TV will display the picture for the left eye and the picture for the right eye alternatively (alternate frames). The physical format required by these two kinds of 3D TV is different: for the passive set, the picture is interleaved in space, for the active set it is interleaved in time.
However, consumer 3D TV sets all offer features converting other input formats to their native physical format. For instance, they will normally all accept a video stream where frames are sent one after another (alternate frames). The passive TV set will send the first frame to the even rows, the second frame on the odd rows, and so on. This choice of logical format is made with the remote control of the TV set, using the 3D input menu.
There are logical formats that do not directlly correspond to a physical format. For example, many videos are available in side-by-side format, where the two pictures each occupy half of the frame. This is the format of the pictures generated by the Sony Bloggie3D.
All combinations of logical and physical format do not deliver the same picture quality. For instance, if you show a side-by-side video on a passive TV set, you will divide the horizontal resolution by two (because of the side-by-side format), and then again by two vertically (because each eye only sees every other scanline). If possible, it is better to use an "over-under" format where the vertical resolution is already divided by two, but there is no loss in horizontal resolution. The resulting picture will be sharper.
In general, the best quality will be achieved with alternate frames, since in that case two full-frame pictures will be sent to the display. With the right hardware, you can get true Full HD resolution with each eye. You can even go beyond Full HD, for example with digital cinema 4K projectors.
Unfortunately, there is another factor to consider here. The majority of consumer-grade graphic cards will not generate alternate frame signals for OpenGL applications. The corresponding feature, called "Quad buffers", is reserved by nVidia and AMD to their high-end professional cards.
This limitation applies to Windows PCs. Apple Macintosh computers generally offer support for Quad Buffer, except for the last generation of entry-level laptops equipped with Intel HD graphics.
Tao Presentations automatically detects whether Quad Buffer is available or not. If you see a menu entry called "Enable stereoscopy" in the command menu, or "3D (quad buffer)" in the View>Display mode menu, then you are lucky: your card supports OpenGL quad buffer, and you should be able to generate alternate frames.
If you use a computer to generate a stereoscopic picture on a 3D TV, you also need to disable overscan. Overscan is a mechanism which crops and scales the picture, and is unfortunately enabled by default on most consumer HD TVs. As a result, one pixel sent by the computer no longer directly maps onto a pixel on the screen, even if the resolutions are 1920x1080 in both cases.
This mechanism gets in the way of stereoscopy, in particular for all geometric modes (side-by-side, over-under, interlaced). In that case, pixels for the left and right eye are no longer exactly where they should be, resulting in a blurred image, ghosting effects, or misaligned left and right eye pictures.
To use stereoscopy, it is critical to disable overscan both on the TV set and on the computer. The way to do that depends on the TV set and operating system. On most TVs, it is an option with a strange name, like "Just scan" on some LG TVs. On the PC and Macintosh, you can find the overscan adjustments in the control panel for the display.
Understanding how 3D works is a bit complicated, but the reward is worth the journey. A real-time 3D display like the one Tao Presentations offers makes it easy to have fun exploring depth effects, whether with 3D objects or with movies, picture or text.