The technique of rotoscope involves the process of creating animated sequences by tracing frame by frame from live-action footage, facilitating a realistic interpretation of the actions and movements of the characters and objects that are to be animated.
For this film, with the intention of using new digital tools to simplify a segment of the production that tends to be time-consuming and lacking in creativity, we aimed to integrate EbSynth, a software that is publicly available and free. It combines the movements captured in a live-action video with the painting style used in a given image. The program's website has an explanatory video that provides a better understanding of how it works – it can be viewed here.
In our case, for each shot we wanted to animate, the video of the corresponding live-action footage - filmed in Guatemala during the first phase of production of the teaser - was inserted into the program, along with reference drawings or keyframes that established the desired overall graphic appearance for the shot.
For this 17 seconds long shot (136 frames at 8fps), we made six key drawings:
The program uses the shapes and movements captured in the video and overlays them with the graphic quality, tones, and textures of the provided drawings. Depending on the complexity of the footage—such as the number of characters, organic elements, patterns, or very rapid movements—the results may exhibit a variety of errors, which typically manifest as smudging and distortion of shapes.
Once EbSynth processes all the images, it will export them into different folders. For each given keyframe, it creates a sequence of images that goes from the previous keyframe to the keyframe that follows. For example, in the shot demonstrated above we've given EbSynth 6 different keyframes - 000; 028; 061; 098; 113; 130. For keyframe 000, since it's the first one, it created images that go from 000 to 028; for keyframe 028, it created images that go from frame 000 to frame 061, and so on.
This means that EbSynth will create more than one image for each frame of the sequence. To resolve that, we import all the frames in separate layers and, using the animation curves, blend the opacity levels until we get a fluid animation to work on.
If the distortion is significant and occupies a large part of the shot, we proceed to create new reference drawings, running them through EbSynth again. Sometimes this solves a large part of the problem, as the program then has more information to position the drawings correctly.
Although the results obtained do not perfectly match what was intended, the use of EbSynth accelerates much of the animation process, requiring only a final correction of the shapes and textures that resulted in errors. However, this work becomes significantly simpler, as it is based on drawings that are already initiated and nearly complete for each frame.
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