to construct proper 3D scaffolds. Similar sorts of geometric “bestpractices”
are common both in design drawing and in 3D modeling,
suggesting that users will find this learning process to be tractable.
Even with the constraints that analytic drawing places on the
sketching process, comments from architects and designers have
been highly positive, and we have found a strong stated preference
for drawing from a single fixed view. While we suspect benefits
of occasional camera manipulation would quickly be discovered,
single-view drawing appears to be highly valued by artists, and may
provide a more gradual transition to advanced 3D drawing techniques.
Our interface is particularly suited to architectural drawing
(Figure 16), and could also be used to reconstruct objects from photographs
[Sinha et al. 2008], even those with curved surfaces.
Our scaffold drawing techniques may be beneficial in less constrained
tools [Bae et al. 2003], while their similarity constraints
could also be integrated into our inference engine. A hybrid approach
would allow the designer to draw freehand, but also construct
accurate scaffolds when desirable. In light of perceptual
drawing limitations [Schmidt et al. 2009], this is likely to be necessary.
We have frequently encountered disbelief from those who try
our software and find that their perspective intuition can be radically
incorrect. This discovery is virtually always followed by a suggestion
to provide our tool as a teaching aid for perspective drawing.
Since one of our goals was to explore the boundaries of a “pureinference”
drawing tool, we took a minimalist approach to our analytic
drawing interface. Sketchup-style interactions for specifying
dimensions, scaffold editing, and simple 3D tasks like extrusion,
would improve design efficiency. Recent work in variational editing
of curve networks [Gal et al. 2009] could be adapted to deform
scaffolds while taking our inferred constraints into account.
However, we do find it quite satisfying to simply draw, without the
need for more traditional interactions. In that context, interesting