Advanced, Experimental VFX Animation and Techniques
Blog WK#2 (Jan 13), Rotoscoping.
HISTORY
The term 'rotoscoping' refers to different procedures in animation vs VFX. In animation, the procedure, which dates back to Max Fleischer (1915), involves tracing live action footage, frame by frame, to generate a cartoon-like image which is then used as an animation. The process initially required projection of the live action footage onto a glass screen which then allowed for tracing. The projector was called a rotoscope. This is portrayed below in the patent drawing for Max Fleischer's technique; his first published work implementing this technique was entitled "Out of the Inkwell" (wikipedia, rotoscoping, 2020).
Blog WK#2 (Jan 13), Rotoscoping.
HISTORY
The term 'rotoscoping' refers to different procedures in animation vs VFX. In animation, the procedure, which dates back to Max Fleischer (1915), involves tracing live action footage, frame by frame, to generate a cartoon-like image which is then used as an animation. The process initially required projection of the live action footage onto a glass screen which then allowed for tracing. The projector was called a rotoscope. This is portrayed below in the patent drawing for Max Fleischer's technique; his first published work implementing this technique was entitled "Out of the Inkwell" (wikipedia, rotoscoping, 2020).
DEFINTION OF A 'MATTE'
In VFX, rotoscoping involves the process of creating a matte. As per class dialogue, a matte was defined as a mask. This dialogue, however, was quite limited and didn't elaborate upon what was meant by "a mask". For example, one could readily imagine that the mask (or the matte) is the component of the footage which is liberated by deleting the irrelevant background. Indeed, our day-to-day use of the term 'mask' most typically references a costume element that is used to cover one's face. That is, the mask is (obviously) the tangible object that conceals a person's face; the mask itself is actually the endpoint for the entire costume process.
Upon review of the UAL required reading textbook Digital Matte Painting (Mattingly 2011), the process of generating a matte refers to "the section of the filmed footage that is blocked or matted out..." and involves "...cutting a black mask, or matte" from a frame. The section matted out can then receive whatever preferred imagery.
In VFX software matting proceedures, as below, the white central circular area is destined to remain and it is the black outer area that becomes transparent and would thus be considered the section that is matted out. As a technical detail, the pixel luminance value for white is 1 and the value for black is 0. Decimel pixel values form 0.9 to 0.1 represent darkening shades of gray, which correspond to decreasing degrees of transparency.
Rotoscoping: Subregion and Animation
The main intent with rotoscoping a plate is to isolate a ROI and modify that area of the frame independently from the remainder of the frame. This focused subregion can then be a target for animation. The following IMG shows a character’s eye, which has been outlined by means of rotoscoping. The character’s eye will move throughout the footage, thus the roto position needs to change accordingly, i.e. it requires animation.
Rotoscope Editing: Tool of Choice
The process of generating a roto by means of the bezier tool is quite problematic, e.g. each vertex is associated w 3 adjustment contacts (the vertex itself and the vertices’ 2 handles). In contrast to the classic bezier tool, the Bspline tool allows for smooth lines to be generated and doesn't involve additional handles (IMG below, women’s face, L frame). The Bspline tool is best for organic, nicely smooth edges. The cusped bezier tool is better for mechanical or hard edges, eg square edges (women’s face, R frame).
The process of generating a roto by means of the bezier tool is quite problematic, e.g. each vertex is associated w 3 adjustment contacts (the vertex itself and the vertices’ 2 handles). In contrast to the classic bezier tool, the Bspline tool allows for smooth lines to be generated and doesn't involve additional handles (IMG below, women’s face, L frame). The Bspline tool is best for organic, nicely smooth edges. The cusped bezier tool is better for mechanical or hard edges, eg square edges (women’s face, R frame).
