3D Modeling and Animation

Transcription

1 3D Modeling and Animation An Introduction ( Stephanie O Malley ) University of Michigan 3D Lab Digital Media Commons, Library

2 What does CGI Mean? CGI Stands for Computer Generated Imagery. It is the application of computer graphics to create images for a variety of uses. While the use of CGI is most commonly associated with the Entertainment industry, it also has uses in a variety of other fields, such as: Manufacturing Advertising Medicine Forensics Engineering

3 What s in a CG Image? Computer Generated Images often end up as pixels on the screen, but those pixels can be created from a wide range of elements including: 3D Models Digital Paintings Photo Manipulation Procedural Shapes and Patterns Many many more 3D Models will be the focus of this presentation.

4 Who Makes 3D Models? Quality 3D Models can be generated in many different ways and can leverage many different skill sets including: Artists - using reference images, concept art, or their own imagination they create a 3D Model Programmers - often generate 3D Models using computer algorithms or code. Digital 3D models can also be created from real objects that already exist or scientific data. Sometimes this is achieved by capturing an object using a series of photographs in a process known as Photogrammetry, or through the use of a 3D laser scanner.

5 Artists as Creators 3D artists use a variety of 3D software to generate models including: 3D Studio Max, Maya, Blender, Rhino, etc. Each program allows for different ways to create the 3D Model. Programs such as Zbrush, allow an artist to sculpt a digital model, just as they would with clay. This allows for highly detailed 3D models to be generated and is often used for creating assets in movies and video games.

6 Engineers as Creators Engineers and Designers also use a variety of 3D software to generate models including: SolidWorks, Sketchup, Catia, Pro/E, Inventor, etc. While these programs are focused more on specific industries or uses of 3D Models they provide unique tools to speed up the process. Software such as Solidworks allows one to enter specific coordinates, dimensions, etc. to get accurate models ready for manufacturing.

7 Programmers as Creators Programmers tackle the creation of 3D Objects a little differently. They often use algorithms and code to generate the desired models and shapes. This can be done using low-level APIs such as OpenGL and DirectX, or higher-level toolkits and libraries such as VTK. Creating models through programming gives the unique ability to drastically change the 3D Model interactively based on user input, musical notes, sensor data, etc.

8 Photogrammetry Photogrammetry is the practice of determining geometric properties of an object from a series of photographs. These photos are imported into specialized software such as 123D Catch, PhotoScan, etc. which then uses points within the photos to triangulate a 3D object s position in space.

9 3D Scanning 3D Scanners can take many forms: Lasers - A laser is used to pinpoint targets placed on, or around, the object to get orientation. The laser then measures its distance to the surface creating a mesh. Structured Light - A grid is projected onto the object. The distortions in the grid reveal the shape of the object. Depth Cameras - Similar to Structured Light, devices like the Kinect project a pattern on the world and look at distortions to determine depth. From there a mesh can be created.

10 What is a 3D Model Made of? A 3D model is fundamentally comprised of triangles, also known as faces or polygons. Each polygon is made up of vertices and edges. When these polygons are positioned and stitched together, they create a surface.

11 The Power of Primitives Primitives are basic 3D shapes that can be easily created and customized procedurally. Each program has their own set of primitives available. Some even have doors, trees, and staircases. Combining these basic shapes allows you to create some complex scenes.

12 Animation We perceive motion as a series of images played back in rapid sequence. Each image differs slightly from the one before it. Animation is the creation of these images. Eadweard Muybridge, Animal Locomotion #617, 1887

13 3D Animation 3D animation is the process of applying motion to a 3D object. This is done either through: Skilled Animators Motion Capture Procedurally (via Code) Animating 3D objects is very similar to animating in 2D, or the process of stop-motion animation. An object s location or appearance is set for specific moments in time (called keyframes). When these movements are played back in sequence, you get a 3D animation.

14 Keyframe Animation In traditional animation, lead animators draw the important poses and then handed the drawings off to an inbetweener to fill in the blanks. In CG, the computer assumes the role of inbetweener by filling in the blanks between the important poses (keyframes) by interpolating between them. For believable animation, animators abide by a series of animation principles that dictate rules for conveying realistic weight, anticipation, and distortion.

15 Skeletal Animation Animated characters use a skeletal system to drive their motion. This is referred to as a Rig, and consists of a hierarchical set of connected bones, much like a human skeleton, and controllers to help the animator pose the character. Each bone is manipulated by an animator to create different poses for animation. The regions of the mesh are bound to specific bones (i.e. Skinned) and follow their movement, deforming as needed.

16 Motion Capture Motion Capture can take a variety of forms: reflective markers on joints gyroscopes or accelerometers magnetic fields mechanical structures fixed to the body The resulting data can be used to track people/animals, robots, deformation of objects, etc. and then analyzed for biomechanical anomalies or even used to animate a digital character.

17 Rendering Rendering is the process of converting models into pixels for storage in an image or to display on screen. When CG movies are created, each frame of the film is sent to a series of computers to be generated into an image. This process can take hours, even years, depending on the length of the film and the number of computers producing the images.

18 Render Farms To speed up the rendering process, CG images are often sent to a group of computers for processing, referred to as Render Farms. Render Farms split the rendering workload among many separate computers. Digital Domain Render Farm

19 Real-time Rendering Real-time rendering is when a scene is rendered and displayed on screen in less than 1/15th of a second. To obtain interactive rates, certain considerations need to be made when creating models and animation for real-time. Because rendering occurs so quickly, real-time applications are typically interactive. Games and Visual Simulations are often classified as real-time applications.

20 Uses - Entertainment CGI is most commonly used in the Entertainment Industry for films or video games. Films like Lord of the Rings or Avatar make heavy use of CG creatures, animated to be very life-like through the use of Motion Capture.

21 Uses - Advertisement CGI is used heavily in the advertising industry. Most cars you see in auto commercials are CG because this allows them to be depicted in any environment while looking as perfect as possible.

22 Uses - Architecture Architectural spaces are expensive and traditional models are limited. Creating an architectural space in 3D allows for easy revision and presenting of designs. Animations can be used to give viewers a virtual tour of the space. Line of sight, shadow studies, and other tests can be done accurately before ground is broken.

23 Uses - Reconstructions With natural and human influences wearing down archeological treasures, documenting and preserving these pieces of history is a constant battle. Geometric modeling and animation can be used to digitally reconstruct historical sites and objects. Photogrammetry is a popular choice for creating historical models.

24 Uses - Natural Sciences Geometric modeling and animation allows for easy visualization and exploration of complex datasets. Elaborate processes such as protein synthesis or the formation of vortices can be demonstrated though animations. Extraordinary phenomena such as the solar winds or microbial interactions can be shown. Extinct animals and life-forms can continue to be studied and shared.

25 Uses - Medicine Geometric modeling can offer a unique perspective on a patient s existing condition. It can help explain complex forms or demonstrate elaborate processes through strong visual models and animations. Geometric modeling can even serve as a 3D blueprint for the creation of prosthetics or orthotics.

26 Uses - Emergency Medicine 3D Models and Animation can be used with great success in training medical personnel in stressful and otherwise dangerous situations such as mass-casualty events. 3D models also help reinforce prior training by allowing for unlimited scenarios and events that can be easily switched or modified.

27 Uses - Engineering Geometric Modeling has been tightly integrated with the fields of Engineering and product design for many years. Digital data (CAD, or otherwise) is already available

28 Uses - Manufacturing 3D models can be used to generate working prototypes or molds. In this process, 3D models are sent to a 3D printer, which converts them into tangible objects by layering material (such as metals, plastics or powders) to build up a 3D form. The resulting objects can then be cast to create molds for manufacturing.

29 Uses - Forensics 3D models are becoming more frequently used in the field of forensics to document important evidence. 3D models can also be used to re-enact scenarios or visualize facial characteristics from a body.

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