PRODUCTION OF COMPUTER-AIDED TACTILE MAPS FOR THE BLIND

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1 PRODUCTION OF COMPUTER-AIDED TACTILE MAPS FOR THE BLIND Servet OZAGAC Head of Relief Map Section General Command of Mapping Dikimevi Ankara TURKEY Tel: , Kemal SAFAK Project Officer General Command of Mapping Dikimevi Ankara TURKEY Tel: ,

ABSTRACT This paper explains the new process by which computer-aided manufactured midform moulds (vacuuming moulds) were prepared for the production of tactile maps.

This was followed by a serial conversions in the formats reaching the resultant *.wnc fit for CNC-Freeze.

Introduction: General Command of Mapping (GCM) is the National Mapping Agency (NMA) for Turkey and responsible for the topographic mapping of the country in hard copy and digital forms ranging from

Additional maps of different types are also produced at various scales with a view to meeting the requirements of the public.

2 ABSTRACT This paper explains the new process by which computer-aided manufactured midform moulds (vacuuming moulds) were prepared for the production of tactile maps. In the process, digital elevation matrix was obtained assigning elevation to each pixel in raster image proportional with the scale. This was followed by a serial conversions in the formats reaching the resultant *.wnc fit for CNC-Freeze. The vacuuming mould made from midform that can endure thousands of vacuuming was finally created and tactile maps of the same quality and standart were produced. Introduction: General Command of Mapping (GCM) is the National Mapping Agency (NMA) for Turkey and responsible for the topographic mapping of the country in hard copy and digital forms ranging from 1/25 K to 1/500 K. The production is naturally not limited to the topo-maps. Additional maps of different types are also produced at various scales with a view to meeting the requirements of the public. Among them are relief maps needed and used for 3-D representation of the terrain. GCM has dedicated one of its sections to production of relief maps demanded increasingly by the public due to their ease of use and attractiveness. Not only the relief maps are produced but also some products needed for educational purposes are included in the products. Some specific models required for science lessons at primary and secondary schools, for instance, head, skin, nose, kidney (urine system) (Figure 1). Figure 1: Different anatomic models for schools. The relief maps previously produced from chalk models were produced again for a total of 16 administrative and physical tactile maps at various scales for different regions of the world, Asia, Europe, Africa, America. In / scaled relief map of Everest and 1/4000 scaled map of Nasca region/peru are produced for ETHZ.(Swiss Technology Institute). In these maps the orthophoto image used as texture (Figure 2).

Figure 2: The Nasca and Everest orthophoto Relief maps.

Conventional method had been used till 2000, which is now totally obsolete.

machine used by an operator manually aiming to create the first model with steps.

As might be appreciated, the accuracy of the model in this model was completely dependent upon

The production of a map used to take about 16-20 working days.

3 Figure 2: The Nasca and Everest orthophoto Relief maps. The Nasca orthophoto relief map can be seen in Palpa Archaeological Museum. Conventional method had been used till 2000, which is now totally obsolete. As this method necessitated, the chalk block had to be engraved in the beginning by drilling machine used by an operator manually aiming to create the first model with steps. This had been followed by pouring the liquid wax onto the model to fill the sharpness between the steps. The model had then been retouched to obtain a completely smooth wax model, which had been used to get second chalk model. The resultant model, the vacuuming one, had finally obtained from the second chalk model. As might be appreciated, the accuracy of the model in this model was completely dependent upon the skill, attention and patience of the operator. The production of a map used to take about working days. Additionally, the number of relief maps produced was confined to as the model was soon affected during the production. Due to the increase in the requirements and developments in the computer technology, after a 5 years research through the CAM (Computer Aided Manufacturing) which has been commonly used in various production lines in a large number of engineering disciplines, the classical system was abandoned in 2000 and computer aided production system has been installed. This system consists of a CNC vertical machine (Figure 3), a CAM software and two PCs (Figure 4). Figure 3: CNC Vertical Drilling Machine. Figure 4: CAM Software.

4 The input for the system is digital elevation data of the terrain. The material used as model is midform. Having the new production system at our disposal now, we can produce the land model with 0.01 mm accuracy, reducing the number of personnel in production to 50%, the production time to 1-2 days with almost no limit in the number of copies which were previously peculiar to the chalk model. Drawbacks of the Chalk Moulds: Previously, the moulds of the tactile maps required by the blind were being produced from the chalks, as this was generally the most common solution for the producers. However, a reasonable number of drawbacks, most of which were listed below, were encountered during the production line: a. A maximum of 50 vacuuming resulted in deformation of the chalk mould. This being the case, a new mould was produced. b. Sometimes the mould was broken and then resulting in production of a new one. c. It was not so easy to mould or place the blind alphabet on the mould, nor was it possible to stick it to the mould. As a result, it was too difficult for the blind to feel the letters properly. d. The symbols on the map were of not the same standard as each one of them was molded manually. This caused problems for the blind when detecting the symbols and distinguishing from each other. e. It was not easy to keep the chalk mould for a long time, as they could dry, crack and possibly break leading to production of a new mold. New Production Line: When GCM received a new request for the production of tactile maps of both Turkey (administrative and physical) and world (physical), we decided to introduce a new production line which utilizes computer and a new material called midform, due to the problems mentioned above. The midform is unique in structure and endurance and would remove all problems when compared to the chalk. It is of plastic origin, easy to cut in CNC vertical machine and hard enough to resist abrasion, cracks, breaks and dimensional change and fit for the blind alphabet. Besides, as the literature put it, the material used many times has been proven to be very appropriate for vacuuming and production of relief maps. One of the constraints for the delivery of the products was that the time allocated to us was limited and we were in a position to follow a very simple algorithm avoiding complexity. The raster image of the physical map of the world at a scale of 1/ was shown in Figure 5.

Figure 5: Physical map of the world at a scale of 1/ 50.000.000 The same process was applied for the production of Turkey administrative (Figure 6) and physical maps(figure 7).

editing and obtaining sparse model. So, a simple data bank at required spacing was not at our disposal.

5 Figure 5: Physical map of the world at a scale of 1/ The same process was applied for the production of Turkey administrative (Figure 6) and physical maps(figure 7). Figure 6: Administrative map of Turkey Figure 7: Physical map of Turkey a. In the beginning, the vertical scale was taken as 1/ accounting for 28 times exaggeration. (vertical scale is 1/ ) b. Though separate digital elevation models (DTM) for different regions of the world having more data than necessary at different spacing were available, they needed a huge amount of work for merging, editing and obtaining sparse model. So, a simple data bank at required spacing was not at our disposal. This forced us to scan the world physical map from the atlas produced by GCM with a resolution of 300 dpi at tiff format. c. Using Photoshop, the scanned map (base map) was color separated, and 7 layers were obtained for 7 hypsometric color ramps. d. Another layer at a different color was prepared for the legend. In Turkey s administrative and physical map, we allocated a wide place at the bottom of the map for the index. Here we put, the number of the city names, mainly, rivers, dams, lakes, mountains.

e. Another layer was prepared for the sea with a spacing and thickness of 2.5 mm. f. The frame of the map was prepared on another layer with a different color. g.

The idea when developing the process was to represent features with different colors each having the same color tone (the same RGB).

The procedure explained above was followed by the storage of all the layers at tiff format in index mode. j.

6 e. Another layer was prepared for the sea with a spacing and thickness of 2.5 mm. f. The frame of the map was prepared on another layer with a different color. g. Another layer was prepared at a different color for latitudes and longitudes. h. Lakes of significant importance were represented at layers each with a different color. The idea when developing the process was to represent features with different colors each having the same color tone (the same RGB). For example, a height of 1500 m was represented with a green tone (R=11, G=213, B=73) and all heights of 1500 m throughout the map was given the same color tone. i. The procedure explained above was followed by the storage of all the layers at tiff format in index mode. j. The image was converted to grid form using the Convert to Grid in theme menu in ArcView Spatial Analyst extension enabling us to have the pixel size of each color. k. In line with the vertical scale of the map, the pixel size of the color in question was edited using Reclassify in Analysis menu. For example, if the height of 1500 m was represented by the number 5 in grid file, we changed this to 1500 taking into account the vertical scale of 1/ l. The new image which produced according to the new height values was converted to grid form using the Convert to Grid command in theme menu in ArcView Spatial Analyst extension enabling us to have the pixel size of each color. m. The grid file was converted to ASCII format selecting ASCII Raster file type using Export Data Source in File menu. n. This was followed by the conversion of the Grid-ASCII file at first to.stl file, a 3-D model format, and then to.wnc file of the software WorkNC (Figure 8). Figure 8: 3-D model format of Physical map of the world of software WorkNC. o. Now, all the input data were ready. After sending the data to the numeric control of the CNC, the machine cut (engrave) the raw midform block automatically and vacuuming model was obtained (Figures 9 and 10).

process was repeated for the preparation

administrative and physical tactile maps.

were used for feature representation such

7 Figures 9-10 : Vacuuming model. On the vacuuming machine we vacuumed each white PVC material on the model and got the map for blind (Figures 11 and 12). We can get countless number of maps on this operation. Because the midform block is very hard. Figures : Vacuuming machine This process was repeated for the preparation of vacuuming models for Turkey administrative and physical tactile maps. For all these three maps, simple symbols were used for feature representation such as sequential small cylinders for borders, squares for city centers etc (Figures 13, 14 and 15).

Figure 13: Physical tactile map of the world.

of Turkey If we have the digital elevation data of the terrain and want to add

to digital elevation data and then merge with the digital elevation data of the

Conclusion: Considering the limited time allocated to us, the idea was to reach

Fortunately the resultant products were very appealing and received many

The process proved to be very effective and encouraged us to attempt new

8 Figure 13: Physical tactile map of the world. Figure 14: Administrative tactile map of Turkey Figure 15: Physical tactile map of Turkey If we have the digital elevation data of the terrain and want to add some symbols to the model, we select the symbols in raster format and transform to digital elevation data and then merge with the digital elevation data of the terrain. Conclusion: Considering the limited time allocated to us, the idea was to reach the target as soon as possible and to have as good maps as possible. Fortunately the resultant products were very appealing and received many praises from the public. The process proved to be very effective and encouraged us to attempt new productions. This method being very simple doesn t take much time, is easy to use for production of countless number of maps. The standard output product can easily be produced using the common software that is known to everybody and be easily used by the blind.

9 Biography of the author: He was born in 1962 in Ankara/Turkey. Having finished his primary and secondary education, he graduated from Kuleli Military High School in 1980, Land War College in 1984 and was commissioned as 1 st Liet. He joined General Command of Mapping (GCM), the National Mapping Agency for Turkey and attended Survey Engineering School, the technical school where survey engineers at GCM are educated, and got BSc degree in 1986 as survey engineer. He started his career at Geodesy Department as geodesist till 1995 taking part in various geodetic projects and field works. In 1996, he was assigned as project officer to Relief Map Section, one of those in Cartography Department. In 2000, he became the head of this section. Among the works carried out during his term are the development of the conventional production system followed by transition from classical to digital production system, now in use. He is still working in this section and currently engaged in increasing the spectrum of the products as well as the quality and accuracy with a view to responding to the requirements of the society.

CHAPTER 3 MARGINAL INFORMATION AND SYMBOLS

CHAPTER 3 MARGINAL INFORMATION AND SYMBOLS A map could be compared to any piece of equipment, in that before it is placed into operation the user must read the instructions. It is important that you, as