adapting a model to a rough user-defined topology

Suppose that I have an mid-high poly model, now suppose that i want to both simplify and modify its own topology, my problem is the following: how to generate the simplified model from a fast or simple reference such as a simple mesh used as cage or a simple shape drawed with the pencil ?

I’m going to describe this with an example.

Imagine that we are in the 2D world, I have a random picture, likely to be complex, for example a human figure, now I draw a square on another piece of paper and I would like to redesign that figure more “squarish” using the square as bounding box.

My problem starts from that idea and goes a little further; since retopoligizing any 3D model having only 1 shape as reference it’s likely to generate an ugly “compressed” mesh ( try the cast modifier with a complex 3D model, especially if it’s taller ), my idea is to assign 1 simple shape at each area, for example, with a 3D model of a human body, I would like to specify a sphere for the head and a cube for each arms, so I can generate a rounded head and more squarish arms.

Advanced options for the angles will be really nice.

This is possible in blender ?

not certain i understand 100 %
but are you having problme making a 3D model from one pic only

did you try Blam which can help in some cases

or problem to make you 3D model then use a lattice to modify it
or the deform modfiier mat be!

happy blendering

no, my problem has nothing to do with photography and Blam it’s out of the domain of this problem.

In other words I would like to create a super-deformed like version of an existing 3D model taking other shapes as main domain, the problem with the modifiers is that they operates 1:1 with the entire model modified based on another model, I need to define bounding boxes for 1 3D model for each user-defined area, the ratio should be 1:X where X is the number of shapes that i need to deform the model as I like.

i can see lattice affecting part of a model
but not vey effective

the other one is the mesh deform modifer
which will modifiy you model into another shape

if you defined your basic model then use the shrinkwrap it should also work to defom part of you shape maybe!

did not use the mesh defomr but i think it does what you want and should use some vert group to select part of your model
did you check it

happy blendering