shapeCAD: An Accessible 3D Modelling Workflow for the Blind and Visually-Impaired Via 2.5D Shape Displays

Alexa F. Siu, Son Kim, Joshua A. Miele, Sean Follmer

Overview of the proposed workflow. Left image shows a snapshot of code written to specify geometry for a mug. Middle image shows a mug corresponding to the script rendered on a 2.5D shape display and the hand of a user feeling the rendered object. Last image shows the 3D printed mug.

We investigate an accessible 3D modelling workflow (shapeCAD) where 3D models are generated through OpenSCAD, a declarative programming language for 3D modeling, and rendered at interactive speeds in a 2.5D shape display consisting of a grid of 12×24 actuated pins.

Affordable rapid 3D printing technologies have become key enablers of the Maker Movement by giving individuals the ability to create physical finished products. However, existing computer-aided design (CAD) tools that allow authoring and editing of 3D models are mostly visually reliant and limit access to people with blindness and visual impairment (BVI).

Through a series of co-design sessions with three blind users of mixed programming ability, we identify accessibility challenges in existing 3D modelling scripting tools and design interactions to support dynamic feedback of scripts using a 2.5D tactile shape display. With these insights, we implement shapeCAD. Interacting with shapeCAD, BVI users are able to leverage the low resolution output from a 2.5D shape display to complement programming of 3D models. shapeCAD allows users to haptically explore and modify existing models, and to author new models. We further validate usability and user experience through an evaluation with five BVI programmers. In a short period of time, novices were able to design a range of new objects. BVI users can bring a valuable perspective to design and it is imperative to increase accessibility in tools that enable this community to also participate as designers.

3D models of objects created by P1 to P5 during the free form creation task. P1 created a 'staircase stand' (15.42 minutes). P2 created a 'tall glass cup' (18.78 minutes). P3 created a 'truck with carriage' (21.09 minutes). P4 created 'a cube with a dome on top' (12.84 minutes). P5 created 'a cylinder cup' (8.01 minutes).

Objects created by all participants during the evaluation’s free form task, the time it took to create them, and participant’s description of the object. The first row shows the rendering of the 3D model and the second row shows the object 3D printed using a MakerBot Replicator. All participants reported being satisfied with the final results except P5.



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