Apple wants to speed up 3D animation on its devices

Posted by Dennis Sellers Jul 1, 2009 at 8:10pm

An Apple patent (number 20090167768) at the US Patent & Trademark Office shows that Apple wants to improve the frame rate display of 3D objects on its devices. In general, this relates to providing 3D animation in an electronic device. In particular, this relates to selectively adjusting the frame rate during a 3D animation for the purpose of optimizing resource use in an electronic device.

Systems and methods are discussed for performing 3D animation of an object using limited hardware resources. When an object is rotated, the size of the object displayed progressively increases, thus taking up more memory, CPU, and other hardware resources. To limit the impact on resources as an object becomes larger, the electronic device may select to display more small frames of the object at a higher frame rate, and fewer large frames at a lower frame rate, thus providing a uniform 3D animation.

Here’s Apple’s background and summary of the invention: “3D animation is used in a host of electronic applications, ranging from the graphics on cellular phones and digital audio player such as the iPod.TM. to sophisticated video games and animated movies. Similar to traditional 2D animation, 3D animation fundamentally involves displaying a series of still images at a rate fast enough to create the optical illusion of motion. Each still image is displayed on an electronic screen by manipulating the color and intensity of the pixels that constitute the display.

“The process of generating a 3D animation usually begins with describing the object of the animation (e.g. the ball in a bouncing ball animation) using a computer model, such as a wireframe model. The spatial and temporal trajectory of the animation sequence is created by providing multiple frames of the animated object in which the object is incrementally changing. The rate at which the frames are provided is referred to as the frame rate. Lastly, each frame (or a series of frames) is rendered to create a realistic 2D image from the 3D model contained in the frame. The rendering process generally uses the 3D model in each frame to determine the kind of texture and lighting that should be applied to the image so that the finished image has perspective and depth.

“The process of creating animation, and in particular the rendering step, can often be computationally very expensive. This can be a particular problem in portable electronic devices, such as cellular phones and digital audio players, where power consumption, memory space, and CPU power are often limiting factors. Thus, there is a need in the art for systems and methods for creating resource-friendly 3D animation.

“Accordingly, systems, methods and computer-readable medium are provided for generating 3D animation using limited hardware resources. Nominally, the images that comprise an animation sequence are provided to a screen at a constant rate. However, the amount of computational resources needed to generate each image is not constant. Generally, images that use up more pixels (i.e. screen area) require more resources to model and render. Large incremental change between consecutive images also often leads to more system resource requirements. The present invention can limit the amount of resources needed to create a 3D animation by selectively decreasing the frame rate of the animation during segments that are deemed too resource intensive.

“The invention can generate 3D animation with frame rates that are dependent on the computational complexity of rendering each image. The system may include hardware that is configured to store a collection of frames that compose an animation of a 3D object. An optimal frame rate for each frame may be computed based on the resources required for each frame. The system may then select a group of frames to render and provide the rendered images at their associated optimal frame rate to a screen, thereby creating a resource-limited animation.

“In one embodiment, the animation is of a rotating object, and in particular, a 2D rotating object such as a music album cover. In this scenario, images of the object that are parallel and almost parallel to the screen are the most computationally expensive to render (i.e., requires significant system resources). Thus, fewer frames of the object in these orientations are rendered and displayed during the animation. The exact point in the animation sequence to slow down the frame rate may be determined by plotting the relationship between the frame number of the animation sequence and the number of pixels occupied by the corresponding image. This plot may be monotonically increasing for a 2D object that is rotated 90 degrees. An upper limit placed on the number of pixels used may translate to the frame number where the frame rate should be decreased.

“The computations performed to generate the 3D animation may be carried out on the same device or in two separate devices or pieces of software. In one embodiment, a preprocessor may be used to cache a collection of frames in memory. The preprocessor may compute the optimal frame rate of each frame and store it with the cached frame in, for example, a look up table.

“During runtime, the same or a separate device/software may select a group of frames from the collection generated by the preprocessor and order the frames such that the desired animation sequence is created. The frames may then be rendered to create the final images that are seen by the user. Each image may be provided at its optimal frame rate.

“In another embodiment, the frame rate during runtime of the system may be a predetermined constant due to the limitations of the hardware or for another reasons. In this case, images with optimal frame rates lower than the runtime frame rate may be held on the screen over multiple frame update cycles, thereby eliminating the need for re-rendering.

“Persons of ordinary skill in the art will appreciate that the at least some of the various embodiments described herein can be combined together or they can be combined with other embodiments without departing from the spirit of the present invention.

The inventors are William Bull, Guy Bar-Nahum and Gokhan Avkarogullari. The graphic shows an illustrative electronic device with a display that can be used in accordance with one embodiment of the present invention.

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