I came across something that I wanted to share. Maybe you know this already, but convert3d.org is not only handy, it also makes use of Babylon.js (see Hello, Convert3D! - Convert3D)! Without uploading your 3D art.
Marilyn Monroe 2.5D breakdown:
-broke the photograph down into layers based on parallax of sections of her body (hair bangs, face, back hair, arm)
-created rotos for all of these layers (I used photoshop, but any image manipulation software can be used)
-created clean plates for any sections of the layers that may be revealed (also done in photoshop)
-imported each layer individually into Blender using the Point Convert 3D plugin (pointconvert3d.com)
-created a mesh on the image plane of each layer using the knife tool and visualizing which areas will need to be extruded to build out the shape of the object
-converted the mesh into individual points (vertices) that can be extruded to build out objects in 3D space while maintaining the integrity of the original image (this is done using the convert button in the Point Convert 3D plugin
-built out the layers in 3D space in Blender
All of the above steps are demonstrated in the pointconvert3d.com tetherball tutorial
-after the conversion was complete I deleted all of the bones and modifiers used to build the mesh in 3D space, but kept the newly created mesh with their textures (currently, this all has to be done manually, we are currently developing a tool that will do it for the user)
-last, I put a simple rig on the mesh layers and animated it