Tactile Chart Generation Tool
Cagatay Goncu, Kim Marriott · 2008 · Proceedings of the 10th International ACM SIGACCESS Conference on Computers and Accessibility (Assets '08) · doi:10.1145/1414471.1414525
Summary
This paper presents a Java application that automatically generates tactile bar and pie charts from raw data values provided in a formatted text file. Developed in collaboration with Vision Australia, the tool addresses the time-consuming and expensive process of manually creating tactile versions of charts found in educational materials for students who are blind or have severe vision impairment. Transcribers at Vision Australia had been producing these graphics by hand in CorelDraw, which took approximately 30 minutes per chart. The tool reduces this to about 5 seconds. A central contribution is the recognition that good tactile chart layout differs significantly from good visual chart layout. For bar charts, the authors identify key differences: Braille labels require considerably more space (particularly on the horizontal axis, where labels may need to be staggered), additional contextual elements like grid lines and numeric values on bars improve readability, and placing axis titles and legends above rather than below the chart supports top-down tactile reading. For pie charts, smaller segments may need to be split for discrimination, and the authors conjecture that a stacked vertical bar representation may be more readable than a circular pie. The tool outputs SVG with logical structure preserved, allowing transcribers to fine-tune results in CorelDraw.
Key findings
The tool supports multiple layout styles for both bar charts (vertical, horizontal, stacked, compound) and pie charts, with configurable parameters including bar gaps, page margins, and page size. It produces both Grade 1 and Grade 2 Braille labels and handles multi-dimensional data. A particularly challenging technical problem was ensuring non-overlap of Braille labels and diagram components — since Braille cannot be resized like printed text, the tool tries multiple layout configurations until finding one without overlap. Initial feedback from Vision Australia transcribers and proofreaders (many of whom are blind) was extremely positive, especially regarding the dramatic speed improvement from approximately 30 minutes to 5 seconds per chart. The tool was being trialled to assess flexibility, output quality compared to hand-crafted charts, and overall workflow improvement. The authors note that no comparable tool existed at the time, despite the apparent simplicity of the concept — Google Charts could generate visual charts from text but had no tactile option, and the existing Tactile Graphics Assistant merely replaced visual text labels with Braille without adapting the chart layout itself.
Relevance
This paper highlights an often-overlooked aspect of accessibility: the production pipeline for alternative format materials. While much accessibility research focuses on end-user interaction, this work targets the transcribers and educators who create accessible content, dramatically reducing their workload. The insight that tactile layout requires fundamentally different design decisions from visual layout — not just a mechanical translation — is critical for anyone producing accessible data visualisations. The specific guidelines (stagger labels, place legends above, consider horizontal bars, add contextual information like grid lines and trend lines) provide practical design patterns applicable well beyond this specific tool. For accessibility practitioners working in education or publishing, this paper demonstrates the value of semi-automated tools that respect professional judgment while eliminating tedious manual work, and reinforces that accessible formats deserve purpose-built design, not just visual-to-tactile conversion.
Tags: tactile graphics · data visualization · visual impairment · braille · accessible publishing · education · assistive technology · design tools