@phdthesis{Alex:2005:HSN,
  month = feb,
  optaddress = {},
  author = {John Alex},
  optkey = {},
  optannote = {},
  opttype = {},
  url = {http://groups.csail.mit.edu/graphics/pubs/thesis_jpa.pdf},
  abstract = {This thesis investigates the geometric representation of ideas
              during the early stages of design. When a designer's ideas are
              still in gestation, the exploration of form is more important than
              its precise specification. Digital modelers facilitate such
              exploration, but only for forms built with discrete collections of
              high-level geometric primitives; we introduce techniques that
              operate on designers' medium of choice, 2-D sketches. Designers'
              explorations also shift between 2-D and 3-D, yet 3-D form must
              also be specified with these high-level primitives, requiring an
              entirely different mindset from 2-D sketching. We introduce a new
              approach to transform existing 2-D sketches directly into a new
              kind of sketch-like 3-D model. Finally, we present a novel
              sketching technique that removes the distinction between 2-D and
              3-D altogether. This thesis makes five contributions:
              point-dragging and curve-drawing techniques for editing sketches;
              two techniques to help designers bring 2-D sketches to 3-D; and a
              sketching interface that dissolves the boundaries between 2-D and
              3-D representation. The first two contributions of this thesis
              introduce smooth exploration techniques that work on sketched form
              composed of strokes, in 2-D or 3-D. First, we present a technique,
              inspired by classical painting practices, whereby the designer can
              explore a range of curves with a single stroke. As the user draws
              near an existing curve, our technique automatically and
              interactively replaces sections of the old curve with the new one.
              Second, we present a method to enable smooth exploration of
              sketched form by point-dragging. The user constructs a high-level
              ``proxy'' description that can be used, somewhat like a skeleton,
              to deform a sketch independent of the internal stroke description.
              Next, we leverage the proxy deformation capability to help the
              designer move directly from existing 2-D sketches to 3-D models.
              Our reconstruction techniques generate a novel kind of 3-D model
              which maintains the appearance and stroke structure of the
              original 2-D sketch. One technique transforms a single sketch with
              help from annotations by the designer; the other combines two
              sketches. Since these interfaces are user-guided, they can operate
              on ambiguous sketches, relying on the designer to choose an
              interpretation. Finally, we present an interface to build an even
              sparser, more suggestive, type of 3-D model, either from existing
              sketches or from scratch. ``Camera planes'' provide a complex 3-D
              scaffolding on which to hang sketches, which can still be drawn as
              rapidly and freely as before. A sparse set of 2-D sketches placed
              on planes provides a novel visualization of 3-D form, with enough
              information present to suggest 3-D shape, but enough missing that
              the designer can ‘read into’ the form, seeing multiple
              possibilities. This unspecified information---this empty
              space---can spur the designer on to new ideas.},
  title = {{H}ybrid {S}ketching: {A} {N}ew {M}iddle {G}round {B}etween 2- and
           {3-D}},
  school = {Department of Architecture, Massachusetts Institute of Technology},
  localfile = {papers/Alex.2005.HSN.pdf},
  doi = {http://dx.doi.org/1721.1/28749},
  year = {2005},
}