Web ortamında coğrafi verilerin birlikte çalışabilirliğine yönelik yaklaşımların belirlenmesi: Ulaşım veri teması örneği

Abstract

Coğrafi verilerin üretilmesi, saklanması ve güncel tutulması konularında standart bir yöntemin belirlenip izleniyor olması gerekmektedir. Verilerin katkı sağlaması, kaliteli veri üretiminin ardından doğru şekilde kullandırılabiliyor olmaları ve paylaşılabilmeleri ile mümkün olabilmektedir. Coğrafi verinin farklı kurum ve kuruluşlar tarafından kullanılıyor olması, optimum düzeyde bu ilgililerin ihtiyacını karşılaması ile alakalıdır. Bu sebeple aynı veri farklı kurum ve kuruluşlarca defalarca üretilmemelidir. Verinin mükerrer üretilmesi ve kullanılması zamanla güncelliğini kaybetmesine ve kullanılamamasına yol açmaktadır. Farklı kullanıcı ihtiyaçlarını karşılayacak uygulama ve servislerin geliştirilmesi için öncelikle veri/kullanıcı gereksinim analizi yapılmaktadır. Bu analizler sonunda hangi verinin hangi ihtiyaçlar ile hangi uygulamalarda hangi formatlarda kullanılabileceği belirlenebilecektir. İlgili veri altlıkları, gerçekleştirilen analizlere göre üretilen veri standartlarına göre sorumlu veri sağlayıcıları tarafından üretilmeli, güncellenmeli ve diğer kullanıcılarla web servisleri kullanılarak gerçek zamanlı paylaşılabilmelidir. Örneğin ulaşım temasını temsil eden coğrafi veri setleri; kamu kurumlarından özel sektöre, vatandaştan çeşitli ticari uygulamalara kadar birçok alanda eş zamanlı kullanıldığından ortak bir standart dahilinde üretilebilmelidir. Tez kapsamında model bazlı yaklaşım ile coğrafi veri modeli geliştirilmesine yönelik ISO/TC211 coğrafi bilgi teknik komitesi standartları ve web servisleri ile coğrafi verilerin paylaşımına yönelik Açık Coğrafi Bilgi Konsorsiyumu olan OGC'nin standartları irdelenmiştir. Türkiye Ulusal Coğrafi Bilgi Sistemleri (TUCBS) altyapısı standartlarının geliştirilmesi sürecindeki ilgili veri gereksinim analizleri ve ulaşım veri standardı altlık alınmıştır. Yeni bir standart geliştirme sürecinin; çeşitliliği yok etmeden, nitelik kaybı olmadan, birlikte çalışılabilirliği sağlayan, veri bütünlüğü oluşturan ve mevcut verileri anlamlaştıran bir yapıda olması esas alınmıştır. Ulaşım sektöründe açık veri ve açık web servisleri ile veri paylaşımında farklı kurum/kuruluş ve uygulama ihtiyaçlarının optimum düzeyde karşılanması amacıyla deniz, hava ve demiryolu ulaşım hatları ile birlikte çalışabilecek bir karayolu veri modeli geliştirilmiştir. Tekil Modelleme Dili olan UML uygulama şeması ile geliştirilen bu model, GML coğrafi veri değişim formatı ile kodlanmıştır. Tez çalışmasının uygulama bölümlerinde, plot alan için farklı kaynaklardan elde edilen coğrafi veri altlıkları geliştirilen standart dahilinde GML veri setlerine dönüştürülmüştür. Ulaşım veri setlerinin mevcutta kullanılan farklı veri yapılarına dönüştürülmesi ve sektörel uygulamalarda kullanımına yönelik web uygulamaları geliştirilmiştir. Böylelikle açık veri modeli ile üretilen ulaşım veri setinin, WMS web harita servisi ve WFS web detay servisi ile paylaşımı ve görselleştirilmesine yönelik açık web servisleri geliştirilmiştir. Ağ analizleri, doğrusal referanslama, Android mobil, MS Sharepoint ve GTFS gibi açık kaynaklı ve ticari yazılımlarla ulaşım sektörüne yönelik uygulamalar test edilmiştir.

Geographic Information Systems (GIS) allows managing, storing, analyzing and presenting location based data. With built-in and expandable mathematical models, GIS allows analysts to create real-time results to endorse decision supporters. In transportation point of view, GIS has powerful tools that make transportation data sets interoperable. These data sets get used vith GIS applications such as creating transportation networks, railways, aviation, logistics, navigations, naval GIS, public transportation, and etc. Transportation data sets were produced by different institutions such as General Directorate of Transportation, Provincial Public Administration, Metropolitan and County municipalities. Private initiatives have been developed navigation and network management applications using transportation geo-data sets. However, transportation data sets have different quality and content and these data cannot meet transportation applications needs. While managing and storing the data, some problems occur such as re-crating data, duplicate data, application specific data and non-interoperable data. Making data interoperable begins with developing an open data standard and sharing the data with clients that update or use the data created before. So, sharing and publishing datas via GIS Web Services is an important step for managing data. The data created before can be used in multiple applications for multiple approaches. In this study, open web services developed by OGC were examined. Methodology was summarized to develop transportation data model. And then, service based web applications were developed to share transportation data sets. The Open Geospatial Consortium is an international consortium of several companies, government agencies, and universities that studies for developing open web geospatial standards. OGC Standards make spatial data sharing via web based services. Spatial data which has been produced or shared via complex methods is usable for everyone in an easy way. OGC standards can be categorized in four sections. Encoding section handles such as Geography Markup Language, Styled Layer Descriptor, Sensor Model Language and Filter Encoding standards; Data Services section handles Web Feature Service, Web Coverage Service, Sensor Observation Service, Sensor Planning Service standards; Portrayal Services handles Web Map Service, Keyhole Markup Language, Symbology Encoding standards and finally the Processing Services handles such as Gazetteer, Coordinate transformations Service, Web Processing Service standards. Web Map Service is an OGC standard for sharing web maps. By means of WMS, users can reach styled web maps via OGC compatible client applications. Spatial data that stored in relational database software such as Oracle Server, Microsoft SQL Server or PostgreSQL Server, rendered and published as common raster format (jpg, png, bmp) for viewing the web map. Web Feature Service is an OGC standard for sharing the spatial data. As a difference between WMS and WFS, users can reach spatial data that stored in relational database system directly via OGC compatible client application. For this reason, WFS is more suitable for analyzing spatial data. Web Coverage Service is an OGC standard for sharing coverage data. Unlike WFS, WCS describes geospatial raster data sharing rules. Especially remote sensing data such as satellite imaginaries, ortho rectified photos. Like the WFS, WCS is suitable for analyzing raster data. GML is an XML based OGC standard for storing spatial data. GML can store graphical and non-graphical data that linked to location via custom xml application schema. Benefits of GML are, being cross-platform and easily understandable file format. Location based web services such as WFS also uses GML format for sharing the spatial data. Symbology Encoding defines basic class which requires rendering the feature classes. Stored spatial data in relational database systems is rendered via that rules using the colour, size and symbology values. SLD is a SE configurator especially developed for Web Map Services. SLD provides custom symbologies for clients while they are using WMS. So, spatial data sets can be used on various web maps via SLD and WMS. GeoRSS is a kind of web feed that supports location based data. It is a text file which formatted in GML, GeoRSS Simple or W3C's GeoRSS serialization rule. That supports point, line, and polygon geometries. Due to data duplication, re-creating and non-interoperable data sets causes application specific data. So data sets can not meet transportation application needs. Combining the data sets created by different data providers and making them cross-platform open data sets and open web services is the main approach of this study. Likewise, General Directorate of GIS of Turkey has just completed the National GIS (TUCBS) Standard Development Project. In this project the general directorate analyzed 16 ministries for spatial data needs and productions. These analyses and TUCBS Transportation data theme standards are base for this study. Creating, managing, storing and updating spatial data need a standard method to follow. Keeping the data valuable is based on its correct usage and its availability to share. Usage of the data by different users in different organizations is relevant with its meeting optimum user needs. If the same data is created by different organizations repeatedly, duplicating the data causes losing the data's up-to-date state. Data/User analysis is the first work to be done for meeting various user, application and service needs with single data. With the help of these analyses it will be defined that which data is going to be used by which necessities and in which formats. It is important to carry these analyses on the same place where the data produced or used for its operability. For instance, datasets in transportation data theme are used by public institutions, citizens, private sector, and various commercial applications. In this thesis, ISO/TC211 standards for data-model developing and OGC standards for spatial data sharing with web services have been examined. Transportation data standards and requirement analyses, which developed as a part of Turkish National GIS Infrastructure Standards, have been used as substrate. The new standard developing process has been based on preserving the diversity, retaining quality, achieving interoperability, obtaining data integrity and signification of data. For meeting the necessities of transportation sector, in terms of sharing the data via open-data web services, a highway data model was created and can be operable with water, air and rail lines. The model, which has been created by UML schema, is coded with GML data exchange format. Developing spatial data standard is not a new idea. Especially INSPIRE, EuroRoads and TransXML are transportation based spatial data standards that suitable for most of applications. Surely the INSPIRE is the most important standard for European countries. INSPIRE declares the transportation data standard in five segments. Those are; Common Transportation Elements, Air Transport Network, Railway Transport Network, Water Transport Network and Road Transport Network. Using same data in different applications is a sectoral need and only true way to managing spatial data. Making the data meaningful is the goal of GIS. By means of integrated and interoperable standardized data sets all institutes can use the same data set with different privileges. That makes spatial data sets up to date and reusable. Cross-platform data sets such as GML datas and open web services provided by OGC make data sharing meaningful. The geographic data, obtained in the pilot application sections of this thesis, has been converted to GML data sets in the developed standards. Transformation of the data to the data structures, which is being used by sector, has been described including the usage in various applications via web services. Thus, the datasets, which have been created by open data model, has been tested in sample applications intended for open web services, open-source and commercial software.