CREATING TACTILE GRAPHICS FOR SCIENCE, ENGINEERING, AND MATHEMATICS
David Schleppenbach
Director, VISIONS Lab at Purdue University
1393 BRWN Box 88 West Lafayette, IN 47907-1393
Phone: (317) 496-2856 FAX: (317) 494-0239
Email: engage@purdue.edu
http://www.chem.purdue.edu/facilities/sightlab/index.html
Web Posted on: December 12, 1997
The Purdue University VISIONS (Visually Impaired Students' Initiative ON Science) Lab is dedicated to improving opportunities for the visually impaired to study advanced scientific, mathematical, and engineering (SEM) material at the college level. It is composed of three separate divisions: a production facility that produces educational materials for the visually impaired, a research group whose purpose is to design and develop new and better technologies for use by both the blind and the sighted, and a development group, to help disseminate new solutions into the adaptive community. The production lab, in the form of standard operating procedures, has implemented several different means of making pictures, diagrams and other graphical information available to the blind.
One of the primary techniques for the interpretation of scientific information is visualization. Ordinarily, a student uses his or her eyes to receive data and appropriate that data into a cognitive network of related information. This process requires skills such as pattern recognition, data filtering, the detection of critical elements of the data, and, most importantly, predictive generalization. For the visually impaired, and the blind in particular, SEM students must rely on haptic input (input related to the sense of touch) to perform many of these complex tasks. Interestingly, VISIONS Lab studies have shown that while some aspects of haptic input are inferior to those of visual input, others can afford the blind advantages over the sighted. For example, the filtering out of background noise (such as the XY-grid behind a graph) is a simple visual task. Sighted students learn to interpret noisy data at an early stage, and can do so even when the signal-to-noise ratio is quite low. On the other hand, data filtering in a haptic environment can be quite difficult and generally requires a high signal-to- noise ratio. However, Purdue's blind students generally learn stereochemistry (the three dimensional nature of molecular structure) more readily than the sighted, perhaps because the haptic environment of molecular models and tactile graphics is more informative than two-dimensional images drawn on a page.
While it is certain that tactile input is necessary for blind students to interpret complex graphical images, the methods for the creation of tactile graphics are often complex and confusing. The focus of this paper is to describe the VISIONS Lab process for creating tactile graphics. Specifically, the hardware and software advances that the VISIONS Lab has made combined with recent advances in the hardware used for tactile graphic production make the process of transforming scientific information into a tactile format easier than ever before.
The first and most important step in converting scientific information into tactile format is deciding what to convert. Typically, sighted science students are bombarded with thousands of visually oriented graphs, illustrations, and diagrams in the course of a typical semester. Although many of these figures are critical for conveying concepts and relationships of large sets of data, some are merely "window dressing"; that is, some figures are used simply because they are visually appealing. This trend is especially apparent in modern science textbooks, because creating publication-quality documents is now an inexpensive process that anyone can do. For example, many physics texts will "dress up" free-body diagrams with three- dimensional pictures of the various elements, substituting a fancy, CAD-like cutaway drawing of a pulley for the more traditional hollow circle. Ropes in this same diagram may be shown as braided, three- dimensional constructs as opposed to simple lines. Educational content is not lost by removing or simplifying these kinds of figures. Since the process of deciding what figures are nonessential to the core concept required field-specific knowledge, the VISIONS Lab employs one graduate student (called a "team leader") for each course being transcribed. This student, who has teaching experience in the field in question, makes the decisions about what material needs to be converted and how.
The next step is the conversion of the image into electronic format. This paper focuses on methods using an IBM PC running Windows (3.1, 95, or NT). The quickest method is the electronic scanning of the image into a graphics program such as Adobe Photoshop (TM). This is especially useful for biological diagrams involving much detail. In addition, this allows the scanned images to be processed automatically by custom VISIONS Lab algorithms that convert complicated photograph-like images into simple raised line drawings. A second technique is to draw the diagram in a drawing program such as Corel Flow (TM). This is useful for many diagrams in Chemistry or Physics. Finally, the image can be redrawn by hand (either with a digitizing pad or on paper, and then scanned). This is often necessary for extremely complex biological images such as photomicrographs or anatomical illustrations. The VISIONS Lab employs a scientific illustrator for this purpose.
Thus, images can be divided into two categories: those that are diagram-like, and easily reproduced in a technical drawing program, and those that are photograph-like, and require special modifications.
Diagram-like images are generally prepared in one of three technical drawing programs: Corel Flow (for physics, biology, and general use), VISIO Technical (for electronics, computer flowcharts, and other specialized subjects), and Cambridge Software's ChemDraw (for anything dealing with Chemistry). The VISIONS Lab has created special electronic templates for all of these programs that force the student doing the drawing to create diagrams that follow the VISIONS Lab standards for tactile graphics. These templates, along with most of the custom tools used by the VISIONS Lab, are available from Repro- Tronics. Photograph-like images are much more time consuming to convert. The VISIONS Lab research staff has developed a plug-in filter that is compatible with most major graphics packages such as Adobe Photoshop. This filter, with some user input and trial-and-error, allows scanned images to be automatically transformed into line drawings suitable for raising. Although the process takes only a few minutes, it cannot accurately convert 100% of the diagrams in a typical Biology course. For these special diagrams, the VISIONS Lab scientific illustrator laboriously redraws the image into a line drawing suitable for the blind. This process requires much skill and scientific knowledge.
All of the VISIONS Lab tactile graphics are prepared using Flexi-Paper (TM) and the Tactile Image Enhancer (TM) of Repro-Tronics. This material is a fibrous, flexible paper coated with a heat-sensitive, expanding chemical. When heated in the Image Enhancer, any inked areas on the page will raise. The quality and reliability of this media has improved dramatically in recent years. Few other tactile media can rival its resolution (since its resolution is close to that of the print image), and no other media can rival its cost-effectiveness or resistance to creasing. The VISIONS Lab standards (electronic and written) for tactile images are all geared around Flexi-Paper. Flexi-Paper is available in many sizes, but most production is confined to 8.5" by 11" or 11" by 11.5" sized diagrams. Anything larger takes a long time to be explored using the hands, and thus the larger sizes are reserved for special diagrams and tactile posters. The VISIONS Lab has prepared tactile posters dealing with the Periodic Table, Mitosis and Meiosis, the Food Pyramid, and many other subjects, all of which are available from Repro-Tronics.
When preparing the image in electronic format, it is important to keep the diagram simple and straightforward. Overly complex detail such as that present in many print illustrations can be confusing to a blind reader. In general, tactile graphic interpretation can be time consuming and imprecise, so keeping the diagrams simple allows the student to make quick touch overviews and to visualize large-scale patterns. This is very important, as the blind student must develop the same skills in pattern recognition, filtering, and global trend recognition that the sighted learn when processing visual images. For example, print images of the compound benzene can either be hexagons with inscribed circles, or hexagons with three explicit double-bonds. When drawn as a tactile graphic, the hexagon with inscribed circle is immediately recognized as benzene, whereas explicitly drawing the bonds forces the student to laboriously count each atom in the ring. Additionally, blind students need to be able to quickly examine mathematical graphs and recognize them as members of a general category, such as linear, exponential, parabolic, etc. This is critical in a laboratory environment where the blind student must base the next step of the experiment on results gained in the previous step, and graphical interpretation of the data is the only time-efficient way to do this.
After the image has been prepared in electronic format, the labelling must be done. For literary (i. e. non- mathematical) information, the use of the Duxbury Braille Translator for Windows is highly recommended. The literary "tags" are translated into braille using the translator, and the resultant ASCII string is pasted onto the diagram using the Windows clipboard. The tag appears in the drawing program in VISION30, a specialized braille font optimized for use with Flexi-paper, which is printed at a fixed-pitch of 24 points and with a line spacing of 28.5 points. Once pasted, the tag is carefully positioned next to the item that it labels, without interfering with other parts of the diagram. The VISIONS Lab tactile standards set minimum distances between a braille label and any adjacent graphic. Often the hardest part of tactile graphic creation is spacing the diagram and braille tags properly. In addition, the VISIONS Lab has developed many special fonts to aid the sighted in making the spacing for the braille, reading the braille, and even creating raised print. An entire disk of VISIONS production fonts is available from Repro- Tronics.
Besides braille labels, all images are prepared on a common template to make for easier tactile examination. A small square is paced in the upper-right hand corner of each image to indicate the top of the document. Also, the print title and other information is usually placed in the lower right-hand corner for archival purposes. The braille title is usually indicated by a box around the braille, and can be placed in the bottom center of the diagram. However, titles are often placed along the left edge of the diagram (and with left justification), so that the blind reader can find them more easily. This is one of many examples where visually appealing formatting such as centering can be confusing to a blind reader.
Once the tags are in place, the image is printed on a LaserJet printer. The resultant ink image is then photocopied onto Flexi-Paper. This step may require some experimentation to adjust the copier so that the background does not inadvertently raise. In general, setting the fuser temperature as low as possible, selecting the "thin stock" option, using manual bypass for the paper feed, using exit rollers after the fuser, and gently pulling the paper out of the copier as it exits are all techniques that help keep the tactile image quality high by reducing background noise.
Finally, the image must be raised on the image enhancer. It is important to carefully adjust the intensity knob to achieve the desired level of raising. Over-heating will cause the braille to be too "puffy" and unreadable; under-heating will of course not provide a sufficient signal-to-noise level to achieve the tactile sensitivity threshold. When running the image through the enhancer, always let the shortest side pass through perpendicular to the entrance slit. This assures more even heating of the image as it passes the heating element. Finally, activating the paper sensor (by "teasing" an edge of the Flexi-Paper into the entrance slit and then waiting for a second or two) will ensure that the heating element is properly warmed up for consistent raising. Always gently guide the image out of the rear of the enhancer to prevent jams. By following these steps, very high-quality tactile diagrams can be created.
Finally, two manual methods of tactile graphic creation bear mention, since they can be used by the blind and sighted alike. First, the Thermo-Pen (TM) of Repro-Tronics allows direct drawing of raised lines on Flexi-Paper. The VISONS Lab has created a stencil set to be used with this pen that allows both the blind and sighted to create freehand raised line graphics that conform to the VISIONS Lab standards. Second, the VISIONS Lab has developed a Flexi-Paper model kit, which again allows both the blind and sighted to create tactile graphics on the included felt-backed storage case. This is especially important for Chemistry, as the motion of atoms and electrons can be interactively demonstrated by a blind student to a professor or tutor, and vice versa.
In sum, the process of creating high quality tactile graphics has finally reached a stage where it is both fast and cost-effective. The VISIONS Lab currently produces over 10,000 tactile diagrams per semester for Purdue's blind students. When combined with braille materials, this allows blind students the same luxury as sighted students - to have a fully complete science text that contains both print and graphics. With the proper use of tactile graphics for scientific visualization, blind students can hope to pursue many careers in the sciences that were formerly inaccesible.