What are Tactile Diagrams?
Tactile diagrams are the embossed representation of diagrams. The haptic nature of the diagram enables a blind person to access the graphic content, thereby making it helpful for concept understanding.
Existing methods for diagram production are either tedious (requires lots of manual work and thus non-scalable) or expensive, which limits its penetration in the Indian market.
Our process includes the use of design software and CAD tools. CAD stands for Computer-Aided Design, and it involves the conversion of a scanned raster image into 2D vector graphics and then to a 3D modeled file, thereby making the file compatible with 3D printing.
This 3D printed diagram is used for making the master mould, which can generate multiple copies on plastic PVC sheets using the thermoforming process.
Creation of Tactile Diagram
Creating tactile diagrams involves more than converting visual images to raised representations. Touch perception has a lower bandwidth than vision, requiring sequential information gathering. Organizations like the Braille Authority of North America (BANA) and the Royal National Institute for the Blind (RNIB) have guidelines (BANA Guidelines and Standards for Tactile Graphics, 2010) to aid this conversion.
Key Considerations
Simplify diagrams to reduce spatial clutter
Enlarge diagrams to ensure clarity of adjacent lines & textures
Eliminate non-essential elements
Decompose complex diagrams into multiple parts with details
Convert 3D views to simplified 2D representations
Add Braille labels & keys for better understanding
Conversion of Files into SVG
Original textbook images in formats like PDF, JPEG, and PNG are redesigned using software such as CorelDRAW. They are recreated in Scalable Vector Graphics (SVG) format to retain image quality at any size. Different textures, line styles, labels, and keys are incorporated to convey information effectively. The final SVG file is then prepared for production, ensuring accessible and comprehensible tactile diagrams for visually impaired learners.
Multiple Methods of Producing Tactile Diagram
Tactile Embosser
Diagrams are printed on normal Braille paper using embossers like ViewPlus Premier or Index Everest. This method is cost-effective for simple diagrams but unsuitable for complex diagrams due to limited printer resolution.
Swell Paper
Diagrams are printed at high resolution on swell paper, costing INR 100+ per sheet. This method is fast but expensive and not durable, wearing out quickly.
3D Printing and Thermoforming
For large-scale production, the master copies (moulds) are created using 3D printing technology. CAD (Computer-Aided Design) software adds height to 2D SVG images. These images are then printed using a 3D printer.
Deposition Method
This involves using a Roland UV printer to create tactile diagrams by depositing layers of UV ink. It allows high-res, durable tactile diagrams that can include both raised textures and printed colors, suitable for producing complex diagrams with intricate details. It is often used for smaller production runs due to its higher cost.
