An optical 3D illusion can be created using Red and Blue glasses and by manipulating two photos with slightly different angles. In this study the author creates a 3D image by using a different approach, and by not using any camera images, manually draws two almost identical images also using slightly different angles. This method is advanced and not for the beginner. Learning and exposing method how to combine stereoscopic images is needed to understand this non-camera approach.
The PDF format in this link, download for free:
https://www.academia.edu/28932808/STEREOSCOPIC_CRITICAL_BASIC_HAND_DRAWN_IMAGE_APPROACH_TO_CREATING_3D_ILLUSIONS
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