  Complex data visualization design projects often entail collaboration between
people with different visualization-related skills. For example, many teams
include both designers who create new visualization designs and developers who
implement the resulting visualization software. We identify gaps between data
characterization tools, visualization design tools, and development platforms
that pose challenges for designer-developer teams working to create new data
visualizations. While it is common for commercial interaction design tools to
support collaboration between designers and developers, creating data
visualizations poses several unique challenges that are not supported by
current tools. In particular, visualization designers must characterize and
build an understanding of the underlying data, then specify layouts, data
encodings, and other data-driven parameters that will be robust across many
different data values. In larger teams, designers must also clearly communicate
these mappings and their dependencies to developers, clients, and other
collaborators. We report observations and reflections from five large
multidisciplinary visualization design projects and highlight six data-specific
visualization challenges for design specification and handoff. These challenges
include adapting to changing data, anticipating edge cases in data,
understanding technical challenges, articulating data-dependent interactions,
communicating data mappings, and preserving the integrity of data mappings
across iterations. Based on these observations, we identify opportunities for
future tools for prototyping, testing, and communicating data-driven designs,
which might contribute to more successful and collaborative data visualization
design.
