Transfiguration in the Muggle World

1. Transfiguration in the Muggle World

2. Biological Transfiguration • Some animals drastically change appearance from the time of their birth to their adult life. • This process is called “metamorphosis” • These animals include: • Insects • Amphibians • Mollusks • Crustaceans • Echinoderms • This transformation is usually (but not always) accompanied by a change of habitat or behavior.

3. Stages of Metamorphosis • Larva • (Sometimes) Pupa • Adult

4. Examples

5. "Transfiguration is some of the most complex and dangerous magic you will learn at Hogwarts. Anyone messing around in my class will leave and not come back. You have been warned." —Professor McGonagall introducing Transfiguration to her new students

6. What Can You Do?

7. What Can You Do?

8. Pictures thanks to: http://harrypotter.wikia.com/wiki/Transfiguration

9. Human Transfiguration? • So, how’d they do that? • Many of these and other popular images are brought to the silver screen using a computer algorithm called “morphing.” Let’s explore a little about how morphing works.

10. Morphing • What is morphing? • How does it work?

11. What is Morphing? • Morphing is an animated transformation from one image into another • Combines image warping with a cross-dissolve between image elements • Image processing technique used as an animation tool for the metamorphosis from one image into another

12. How does it work? • Computer algorithm that… • Distorts one image at the same time it fades into another • Key points in each image are mapped from the source to the destination image • Computer interpolates between these points , distorting the first image to have the shape of the second at the same time each image is faded.

13. How does it work? • Idea: warp distorts the first image into the second • First image is gradually distorted and faded out. • Second image starts out distorted toward the first and faded in. • Early images in the sequence are like the first image. • Middle image in the sequence is the average of the first source image distorted halfway toward the second one and the second image distorted halfway back toward the first one. • Last images in the sequence similar to second image. • Middle image is the key!

14. Face Morphing • For any morph, the middle image is key • For a face morph, the middle image should look like a real person, but clearly not the first or second image.

15. The Warp • Process warps two images so that they have the same shape • Cross dissolves the resulting images • Deciding how to warp the images varies with the algorithm used to implement the morph.

16. Where have we seen it? • Music Videos • Movies • Television Series • Commercials

17. Techniques • Mesh Warping • Feature Based Image Morphing More information can be found at: http://davis.wpi.edu/~matt/courses/morph/2d.htm

18. Mesh Warping • Relates features with a mesh in the source and destination images • Images are broken up into small regions and mapped onto each other • Users map out a list of coordinates in the first image and a list of coordinates in the second image • The number of coordinates in the source and destination images must be the same.

19. Source and Destination Images

20. The Process • Using a mathematical function, the coordinates from the first image are mapped to their matching coordinate in the second image. • Each frame uses an interpolated mesh as the set of target positions for the input mesh points. • Points in the first image are actually mapped to points in the mesh and then points in the mesh are mapped to points in the second image

21. Mesh Morphing Example

22. Feature-Based Image Morphing • Uses lines to relate features in the source image to features in the destination image • Forward Mapping • Reverse Mapping • Important to map pixels in the destination image to something appropriate.

23. The Process • Using rotation, translation, and scaling, this algorithm uses the pair of lines to map from one image to another.

24. An Example

25. Final Result

26. Animated Sequences? • Morphs are also done in sequences of live action. • Instead of marking corresponding features in 2 images, there must be a set of line segments at key frames for each sequence of images. • Sets of segments are interpolated to get the two sets for a particular frame and then the two image metamorphosis is performed on each frame. • Takes work, but looks cool!

27. Now, It’s Your Turn! • If the computer in front of you is not yet on, turn it on and copy your two photos to the desktop of the machine. • Double click the morph icon • Drag your picture into the left window and the photo of what you’re turning into in the right window. • Using the mouse, draw a line in the source image between your eyes. Then draw a line in the destination image where you want your eyes to be mapped to. • Repeat this with several more lines, then take a look at the morph. • When you like it, save the morph as a QuickTime movie (instructions in class), make a copy, and then drop box it to me. Make sure your name is in the title of the movie.