PORTABILITY OF CARTOGRAPHIC SYMBOLS LIBRARY FOR OPEN STANDARDS

Abstract

The Geological Survey of Brazil has a library of palaeontology symbols to use in geological mapping works, currently in bitmap format and adapted for ESRI platform. This type of representation has presented anti-aliasing problems when reduced, in addition to not being suitable for map presentation on the web, according to OGC (Open Geospatial Consortium) specifications. This work presents a reproducible method in any symbol library type. The method consists of converting the symbol library to open-source format, resulting an OpenType font file, which can be installed on any operating system and view each symbol font in any software that has this functionality, such as a GIS (Geographic Information Systems) software. The need to develop font construction technique is due to improving typographic quality of cartographic representations and making library compatible with main GIS softwares. Those 61 pictorial palaeontology symbols were converted, one by one, to SVG (Scalable Vector Graphics) format. We imported each symbol as a glyph in FontForge font editor. Major computer platforms use OpenType format due to its wide availability and typographic flexibility, including provisions to deal with diverse characteristics of internationally symbolic alphabet systems. There is even the possibility of symbols standardizing in the UTF-8 alphabet system, an issue for the scientific community to study. The advantage of using the SVG format is its size, a compact text file, and has an excellent compression factor. In addition, version-control repositories, like GitHub, can store SVG files, which would facilitate content management. The adopted method proved to be applicable to any cartographic symbols library with good results. Rendering tests on different platforms (web or desktop) showed no noticeable differences. One of the most important aspects of the method presented in this work was to make cartographic symbols library public and open-source for use by the geoscientific community, regardless whether an open-source or proprietary platform is used, and so, the Geological Survey of Brazil will be able to distribute geological symbology patterns, according to Open Data definition.