Chance's "Visual Effects" Lecture


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This lecture was given in Baylor University's Production Methods One course on 9/06/06.

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  • CGI requires a lot of observation. Thanks for sharing such an informative slide.

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  • Chance's "Visual Effects" Lecture

    2. 2. Visual Efx Primer-Film <ul><li>Vis.Efx. Are obvious in certain genres, like Sci-Fi films </li></ul><ul><li>Reality is most films in any genre use some form of Vis. Efx. </li></ul><ul><li>What is the process? </li></ul>
    3. 3. Understanding Digital Efx <ul><li>Typical Efx team includes: </li></ul><ul><li>Artists </li></ul><ul><li>Technicians </li></ul><ul><li>Producers </li></ul><ul><li>Managers </li></ul>
    4. 4. Understanding Digital Efx <ul><li>“ Digital” should tell you it primarily involves computers and software </li></ul><ul><li>Vs. Older forms </li></ul><ul><li>Miniatures, models, etc. </li></ul><ul><li>Thus “CG” or “CGI” </li></ul>
    5. 5. What do you need? <ul><li>3D Software--Maya, 3Ds Max, XSI </li></ul><ul><li>Blue/Green Screen </li></ul><ul><li>Matte Painter--Photoshop </li></ul><ul><li>Compositor--Shake, After Effects </li></ul>
    6. 6. Understanding Digital Efx <ul><li>Advantages of CGI? </li></ul><ul><li>Realism </li></ul><ul><li>Flexibility </li></ul><ul><li>Relatively Low </li></ul><ul><li>Cost (compared </li></ul><ul><li>to alternatives) </li></ul><ul><li>Safe </li></ul>
    7. 7. Understanding Digital Efx <ul><li>The CGI Team is involved in entire </li></ul><ul><li>Preproduction, </li></ul><ul><li>Production, and </li></ul><ul><li>Post-production </li></ul><ul><li>process… </li></ul>
    8. 8. Understanding Digital Efx <ul><li>2 Basic Terms: </li></ul><ul><li>2D Animation </li></ul><ul><li>Done only on </li></ul><ul><li>two axes, the length </li></ul><ul><li>and breadth axes </li></ul>
    9. 9. Understanding Digital Efx <ul><li>3D Animation: </li></ul><ul><li>Adds depth perspective </li></ul><ul><li>Object moving away </li></ul><ul><li>from or to you </li></ul><ul><li>Generally, 3D more </li></ul><ul><li>costly, time consuming, </li></ul><ul><li>Complex, longer renders, larger file sizes </li></ul>
    10. 10. Overview of the Process <ul><li>Typical Movie has around </li></ul><ul><li>1,000-1,500 shots, ranging from 2 seconds to 60 seconds in length. </li></ul>
    11. 11. Overview of the Process <ul><li>A given scene might be filmed w/ a # of cameras -- wide vistas, close-ups, changes of perspective, etc. </li></ul><ul><li>In the final movie, these different viewpoints are mixed together to create the scene. Therefore a single scene might contain dozens of individual shots. </li></ul>
    12. 12. Overview of the Process <ul><li>The first step of the visual effects process is deciding which of the shots need to have visual effects applied to them. </li></ul><ul><li>The rolls of film for these shots are sent to be scanned and used by post houses </li></ul>
    13. 13. Overview of the Process <ul><li>HI-RES. </li></ul><ul><li>SCANNING </li></ul><ul><li>AND </li></ul><ul><li>PRINTING </li></ul><ul><li>Up to </li></ul><ul><li>12,750,000 </li></ul><ul><li>Dots per frame </li></ul><ul><li>(4,096 X 3,112 dots </li></ul><ul><li>per frame) </li></ul>
    14. 14. Overview of the Process <ul><li>Once Digitized… </li></ul><ul><li>Creation / Integration of 3-D models and characters. </li></ul>
    15. 15. 3D Modeling <ul><li>Create a wireframe model by adjusting a series of nodes (or Nurbs) </li></ul><ul><li>This step is frequently eliminated by using motion capture systems . </li></ul><ul><li>Ex: Polar Express </li></ul>Sculpting/Modeling
    16. 16. 3D Modeling <ul><li>Add a rough skin to the model--simple color layers </li></ul><ul><li>This is a rough version of the final model </li></ul>Skinning
    17. 17. 3D Modeling <ul><li>Add a final, realistic texture to the model. </li></ul><ul><li>This texture often comes from actual photos of textures. </li></ul><ul><li>Ex: wood, metals, etc </li></ul>Texturing
    18. 18. Overview of the Process <ul><li>3-D modeling: A collection of shapes (polygons) that form the outside of the object. </li></ul><ul><li>Soldiers in &quot;The Patriot&quot; are formed from of spheres, cylinders and other shapes. </li></ul>
    19. 19. Overview of the Process
    20. 20. Overview of the Process <ul><li>3-D setup - Process of adding a &quot;skeleton&quot; of bones and joints to a 3-D model </li></ul><ul><li>--Often called “ rigging ” </li></ul><ul><li>SO THAT the different shapes in the model move correctly with respect to one another. </li></ul>Bring it to life
    21. 21. Overview of the Process <ul><li>3-D setup cont’d </li></ul><ul><li>In some cases the bones and joints are created by hand. </li></ul><ul><li>In other cases they come from motion capture (MOCAP) or performance capture . </li></ul>
    22. 22. Overview of the Process <ul><li>To gather Motion Capture data, </li></ul><ul><li>--Actor fitted with suit that has reflective markers or lights at every joint. </li></ul><ul><li>--Actor moves on special stage </li></ul><ul><li>--3-D cameras watch the actor from a number of different angles. </li></ul>
    23. 23. Overview of the Process <ul><li>--Computer software tracks all of the markers </li></ul><ul><li>--With help of technicians, binds them together into a stick figure that accurately duplicates the motion of the actor. </li></ul>
    24. 24. Overview of the Process <ul><li>Stick figure is the bones and joints that then control and animate a 3-D model. </li></ul><ul><li>A variety of different poses and activities are captured to provide variety </li></ul>
    25. 25. Overview of the Process <ul><li>3-D Tracking (Motion Tracking) - after scanned in, markers added to the scene to create (in computer) </li></ul><ul><li>--a 3-D model made of the scene AND then </li></ul><ul><li>--a 3-D camera. </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li>GOAL -- 3-D camera to exactly mimic motion of the real camera SO THAT the 3-D elements added look and move as the REAL camera moves in the actual scene. </li></ul>
    26. 26. The Alpha <ul><li>The alpha channel is possibly the most important invention for modern visual effects </li></ul><ul><li>EX: Older Disney cartoons </li></ul><ul><li>Originally people worked w/ just RGB channels…now RGB + A </li></ul><ul><li>Created by former Pixar animator </li></ul><ul><li>Like transparency sheets for projectors </li></ul><ul><li>Background does not exist…usually represented w/ checkerboard </li></ul>
    27. 27. Alpha continued <ul><li>Important Feature**--alpha channel allows for multiple layers on the same frame </li></ul><ul><li>Same concepts used in programs like Photoshop </li></ul>
    28. 28. Overview of the Process <ul><li>ROTOSCOPING </li></ul><ul><li>Process of outlining and &quot;lifting&quot; elements of a filmed scene off the frame </li></ul><ul><li>SO THAT other elements can be added to the frame either in front of or behind the rotoscoped elements. </li></ul>
    29. 29. Overview of the Process <ul><li>ROTOSCOPING: To create this town in THE PATRIOT… </li></ul>
    30. 30. Overview of the Process <ul><li>CGI Artists combined these 2 elements </li></ul><ul><li>Bottom element is the rotoscoped item </li></ul>
    31. 31. Overview of the Process <ul><li>ROTOSCOPING: The final image - elements combined, or COMPOSITED </li></ul>
    32. 32. Overview of the Process <ul><li>Compositing is another technique used in the creation of visual effects </li></ul>
    33. 33. Compositing <ul><li>Basically a layering of video and background elements onto a single output. </li></ul>
    34. 34. + + +
    35. 35. Mattes <ul><li>PAINTING or </li></ul><ul><li>MATTE PAINTING </li></ul><ul><li>The creation of imaginary scenery. </li></ul><ul><li>Once called &quot;airbrushing&quot; -- the process of adding or removing things from a scene. </li></ul>
    36. 36. Matte Painting-Use of Glass Panel: 3D and 2D combined with perspective <ul><li>Required painting with emphasis on realism </li></ul><ul><li>Techniques vary: rear projection, front projection, Latent image projection </li></ul>Images from Hitchcock’s The Paradine Case
    37. 37. Latent Image Matte Painting <ul><li>Photographic tech. of combining 2 scenes </li></ul><ul><li>Runs film through twice, once with a portion blacked out and unexposed </li></ul><ul><li>Can use it now with stills and paintings </li></ul>
    38. 38. Latent Image, cont. <ul><li>Pros </li></ul><ul><ul><li>Original stock quality (highest) </li></ul></ul><ul><ul><li>Matching of hues easy </li></ul></ul><ul><li>Cons </li></ul><ul><ul><li>Hard to estimate needed footage with live action </li></ul></ul><ul><ul><li>Mistakes are expensive </li></ul></ul>Latent image projection used with Matte Painting in Return of the Jedi
    39. 39. Rear Projection <ul><li>Movie projector placed behind glass with painting </li></ul><ul><li>Window covered with frosted plastic </li></ul><ul><li>Camera films from front </li></ul>
    40. 40. Rear Projection, cont. <ul><li>Pros </li></ul><ul><ul><li>Easiest </li></ul></ul><ul><li>Cons </li></ul><ul><ul><li>Loss of image quality </li></ul></ul><ul><ul><li>Least sharp image of all techniques </li></ul></ul><ul><ul><li>EX: Star Wars dog fight scenes </li></ul></ul>
    41. 41. Digital Mattes <ul><li>Mattes can also be CG. </li></ul><ul><li>The cowboys were created separately from the environment. Thus, the BG is a 3D matte. </li></ul>
    42. 42. Digital Painting <ul><li>Examples </li></ul><ul><li>Advantages ( LOTRings) </li></ul><ul><ul><li>Ability to move camera </li></ul></ul><ul><ul><li>No more limitations of pan </li></ul></ul><ul><ul><ul><li>As in Empire Strikes Back </li></ul></ul></ul><ul><ul><li>Reflections and moving animations can be combined easily </li></ul></ul><ul><ul><li>Digital editing is cost efficient and easier </li></ul></ul>
    43. 43. Truman Show : Digital Matte goes 3D A “camera” is tracked w/ image in the exact motion and perspective of the actual camera.
    44. 44. 2D Compositing: Putting all the layers Together
    45. 45. Example 1 - The Patriot <ul><li>Original Shot -- Making it Digital. First the shot’s scanned frame by frame (24 frames per second-20 sec. shot), then each frame is stored as an individual full-color image with a resolution of 2,048 by 1,556 pixels. </li></ul>
    46. 46. Example 1 - The Patriot <ul><li>Rotoscoping : Artist at a computer outlines frame by frame the portion of original shot that’ll be used in the final version -- in this case, a portion of the field and several of the running soldiers. </li></ul>
    47. 47. Example 1 - The Patriot <ul><li>ADD WATER -- 2nd camera crew creates an ocean shot -- </li></ul><ul><li>In this case -- the ocean near Hollywood. </li></ul><ul><li>Once ocean shot is cleaned up & color-corrected, it and the rotoscoped scene can be integrated. </li></ul>
    48. 48. Example 1 - The Patriot <ul><li>Creating The Town -- Another artist creates a Matte Painting of the town. </li></ul><ul><li>This is high-res. digital image was created using a computer painting/illustration package. </li></ul>
    49. 49. Example 1 - The Patriot <ul><li>ADDING THE TOWN -- Once the town is added in, the scene looks like this. </li></ul>
    50. 50. Example 1 - The Patriot <ul><li>Adding boats encircling the town and firing on it. The boats are all CGI-computer generated . </li></ul><ul><li>Each is modeled, then added to the shot. Above is the boat “Mask” - you mask out areas where you want boats to be. </li></ul>
    51. 51. Example 1 - The Patriot <ul><li>Cannon fire for the boats is its own stand-alone effect, created separately, then added. </li></ul><ul><li>Practical EFX added - smoke over the town, people in the town, a large explosion on the right, etc. </li></ul>
    52. 52. Example 1 - The Patriot <ul><li>FINAL STEP, Compositing the different components (rotoscoped foreground, water, town, people in the town, boats, cannon fire, smoke, explosion, birds flying overhead,etc.) LAYER BY LAYER to create the final shot as it appears in the movie. Once digitally composited, the shot is “written back” to film so that it can be spliced into the movie </li></ul>
    53. 53. Example 1 - The Patriot <ul><li>Even though the shot only appears on screen for 20 seconds , hundreds of hours went into the visual effects to create a rich, convincing visual image. </li></ul><ul><li>In &quot;The Patriot,&quot; 150 shots in the film involve visual effects like these. </li></ul>
    54. 54. Titanic: <ul><li>Digital Matte Clouds </li></ul><ul><li>Digital Animation Water (with reflections) </li></ul><ul><li>Model Boat </li></ul><ul><li>Animated People </li></ul><ul><li>Digital Animation smoke </li></ul>
    55. 55. CAST AWAY