GIS PROPRIETARY versus FREE: A COMPARATIVE STUDY USING GEOMEDIA PROFESSIONAL AND GRASS Luis Gonçalves Seco, Miguel Cordero Souto, Rafael Crecente Maseda, David Miranda Barrós Land Laboratory - Department of Agroforestry Engineering University of Santiago de Compostela Campus Universitario s/n Lugo 27002 – SPAIN
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[email protected] ABSTRACT This study presents the results of a comparative analysis of two GIS tools, Geomedia Professional (first fully compliant Microsoft OLE/COM proprietary GIS application) and GRASS (first free GIS). The comparison is carried out through the project ‘Implementation of Cartographic Information for Communal Forests in the Region of Os Ancares’, by evaluating both tools in terms of capability, functionality, ease of use and time of implementation. The analysis reveals that GRASS shows higher capability to analyze and manipulate data, and covers more application areas in GIS projects, while Geomedia Professional shows a more robust graphical interface and DBMS, which reduces the execution time of the project. Although the use of Geomedia Professional involves higher implementation costs, no significant differences are observed in the overall productivity of the project due to the reduction in the execution time. Nevertheless, major differences can be expected for larger projects. Key words: GIS, Free software, Proprietary software, Geomedia Professional, GRASS
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1. INTRODUCTION Proprietary software and free software have the same aims concerning the creation of solutions that use Information Technologies (IT) for process automation. However, both types of software have different philosophies in regard to software development and commercialization. Because proprietary software is more widely used than free software, many organizations do not consider this option (Halloran and Scherlis 2002) for project implementation, and resort to other criteria. Free software (DiBona; Ockman, and Stone 1999) has gradually gained ground in European economy (Greve 2003), and has provided good alternative solutions to proprietary software, as in the case of Linux versus the operating system Microsoft Windows. With regard to GIS, free software currently offers quality alternatives (Wagner 2005) that may become a competitive added value because of their inherent characteristics. Given the relevance of both philosophies, this study presents a proprietary tool and a free tool that have prevailed in the development of GIS software. Based on a proprietary philosophy, Intergraph is one of the world’s leading companies in this area. In the mid-1990s, Intergraph developed the Geomedia architecture (Limp and Harmon 1998); in 1993, the company moved all the applications to the Microsoft Windows platform; in 1997, Geomedia was introduced as the first fully compliant Microsoft OLE/COM proprietary GIS application. Born in 1982, GRASS (Geographical Resources Analysis Support System) (GRASS Development Team 2005b) (Neteler and Mitasova 2002) is the oldest free and costless GIS software that is active. It has played an important role in the progresses made in the Geospatial model, both in education and in the scientific community. Moreover, it has played an important role in the field of business, for the creation of solutions to solve spatial problems.
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2. OBJECTIVES The global aim of this study is to conduct a comparative analysis of functionalities common to almost every GIS software by examining the three-tiers of the classic GIS software architecture [8]. The comparative analysis of the variables mentioned below is carried out by developing the project ‘Implementation of cartographic information for Communal Forests in the region of Os Ancares’ with Geomedia Professional 5.1 and GRASS 5.0.3. The analyzed variables are: 2.1. Capability; 2.2. Ease of use; 2.3. Functionality; 2.4. Time of project implementation;
3. MATERIALS AND METHODS The same hardware and cartographic material were used to implement the project with both applications. However, Geomedia Professional used the Microsoft Windows XP operating system, and GRASS used the GNU/Linux operating system (Debian 3.0 distribution). The information about the Communal Forests (CFs) in Ancares was obtained from cartographic material of the CFs in the province of Lugo, provided by the Department of Forestry of the Province of Lugo. This material was developed in 1977 and 1978 by the Spanish National Institute for the Conservation of Nature (ICONA) by using aerial photographs of the area, scale 1:20,000. The material used included a municipal map of all the CFs in the municipality, scale 1:25000, in paper form. The size of the material supplied was A0. In addition, 1:5000 cartography provided by the Galician government Xunta de Galicia was used in the georeferencing process. Such cartography was developed by the Department of Urban Planning of the Galician Ministry of Territorial Policy,
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Public Works and Housing, and was georeferenced and made available in Microstation CAD Drawing File (DGN) by the Land, Underground and Biodiversity Laboratory (LUB). The execution of the project was divided into six phases (according to the methodology shown in Figure 1). Each phase was assigned scores of 0 or 1. The following features were analyzed:
3.1. Capability This variable assesses the availability of the tools required to perform a given operation, and the potentialities of the software in the analyzed phase of the project. 3.2. Ease of use Connected with the Graphical User Interface (GUI), this variable aims to evaluate the speed and ease of use of the tools supplied by the software in each phase of the project. 3.3. Functionality The analysis of this variable assesses whether the results obtained in each phase of the project correspond to the expected results.
3.4. Time of project implementation The execution times were computed in every phase of the project, implemented for the region of Ancares (Table 1). The learning phase required to develop the project was not computed. Therefore, the analysis of the times was carried out from the moment the user was sufficiently skilled to use the software.
GIS Project Implementation for the three variables of the comparative analysis a) Importing cartography to GIS software Figure 2 shows the methodology used for each tool. In Geomedia, as opposed to GRASS, all the information is stored in one database, which means that alphanumeric data and geometry data are
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stored in the same location. Therefore, before importing the cartography, an Access warehouse must be created from the application. b) Georeferencing The aim of this process (Figure 3) was to establish point correspondences between the nongeoreferenced maps (CFs) and the georeferenced maps (1:5000 maps of the province of Lugo). In Geomedia, this step was conducted by overlaying maps in the original import format. In GRASS, point selection on vector maps is conducted by using the keyboard, while point selection on raster maps is conducted by using the mouse. Therefore, DGN files were converted to raster in order to make the process faster and easier. The georeferencing process was performed with the two images placed beside each other. c) Digitizing The aims of this phase (Figure 4) were to design the CFs based on the georeferenced images, to apply geometry correction functions in order to verify errors, and to associate geometric data with a label that identified them in a single manner, by using vector design tools. d) Database connection With a view to storing the most detailed information about each forest, a database that would match the corresponding label was built (Figure 5). In Geomedia, geometric and alphanumeric data are stored in the same location. Therefore, when a geometric object is created, the alphanumeric fields are also included in Access, in this case. With regard to GRASS, alphanumeric data and geometric data are stored in different locations. Therefore, the data structure and the database had to be created in PostgreSQL, and connected to geometric data through GRASS.
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e) Spatial Analysis A spatial analysis of the area covered by CFs in one municipality of the region of Ancares was carried out. The analyzed forests belonged to that municipality, but their boundaries went beyond the limits of the municipality (Figure 6). In GRASS, the project was implemented with raster tools due to ease of use (r.mapcalc command). Nevertheless, implementation of the project with the vector model could have been performed by using the commands v.cutter, v.patch, v.extract, and v.report. f)
Layout
The printout of a query is presented below. This printout shows the classified communal forests that belong to the municipality of Baralla (Figure 7). In the case of Geomedia, the tools of the print manager (Layout window) were used. In the case of GRASS, the potentialities of the command ps.map were analyzed because the only possibility to print directly from the tool is the use of this command.
4. RESULTS AND DISCUSSION
In general, both tools show similar levels of potentiality and functionality, although they display different features (Graph 1). Geomedia Professional shows a more complete user interface, which constitutes an added value for less experienced or specialized users. 4.1. Capability With regard to capability, the following conclusions were drawn: a) It was verified that both softwares include the tools required to import data. With regard to DGN, Geomedia is capable of gathering more information. However, overall, GRASS shows more capability to import data than Geomedia.
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b) Although Geomedia and GRASS georeference in two different ways, none of the softwares shows further alternatives. c) Geomedia includes more edit tools. One the functionalities that GRASS does not include is the automatic detection of intersections of points and lines, and the capability of making cuts within an area during the digitizing process. In addition, Geomedia includes real-time geometry correction functions. However, such functions need improvement. Moreover, the authors have verified that in Geomedia, this process is directly connected to the database, so that alphanumeric fields and geometry can be simultaneously integrated. d) Geomedia includes a DBMS (Database Management System) that allows read/write access to Access, SQL Server and Oracle databases. GRASS allows access only to PostgreSQL, and does not display so many ‘manipulating’ tools. e) Geomedia includes vector analysis tools. GRASS displays quite powerful tools for raster analysis, which include statistic generation, local operations, neighborhood operations, area operations, extended neighborhood operations, decision-making, generation of elevation models (erosion, hydrology, fires, landscape ecology), etc. In addition, GRASS is capable of analyzing satellite images (color composition, atmospheric correction, geometric correction), etc. f) Geomedia presents a print manager that allows real-time configuration and visualization of the layout. In the case of GRASS, such process must be alternated with a software that visualizes PostScript files. In short, GRASS shows great potential in terms of capability to import and export data, and in terms of the large number of spatial analysis tools by application area, and by data model (vector, raster). Geomedia is associated to better design tools, with the Warehouse concept and a good DBMS that
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allows full integration of geometry and alphanumeric data. Therefore, the digitizing and database connection processes are merged into a single process (Graph 2).
4.2. Ease of use a) All the operations performed in the import process were easier and faster in Geomedia (Graph 3). This result becomes more evident in the DGN import operation because Geomedia includes a more elaborate user interface that allows automatic import of the 230 files required in this case. In GRASS, this process has to be carried out as many times as files have to be imported. A less experienced user must create a script to automatize such process. b) The georeferencing process was faster and easier in Geomedia because this software shows a more intuitive interface, and because map overlaying demands a lower number of operations. c) The design process demands less operations using GRASS. However, Geomedia presents a more integrated and faster interface for digitizing, geometry correction and labeling operations. d) Because in Geomedia the GIS project is directly connected to the database, the whole process of data integration and manipulation is considerably easier and faster than in GRASS. e) In this case, the use of the graphical interface is easier in Geomedia because GRASS does not have a graphical interface for every analysis command. f) Generation of map layouts is easier and faster using the Geomedia print manager. Conversely, generation of maps is difficult in GRASS due to the total lack of a graphical interface. GRASS shows a different working philosophy. GRASS is a command-oriented ArcInfo type application, whose functionality is sometimes poor. For example, the process to import DGN with the command v.in.dgn becomes a complicated operation due to the fact that only one file can be imported at a time. In this study, 230 DGN files had to be imported and the process was very slow.
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With regard to layout output, printing the first map in GRASS is a time-consuming task because the lack of a graphical interface affects the time required to create a sample model. Once the base script is created, the printing process becomes easier. However, this is the least positive aspect of the tool (Graph 3). Geomedia, with a rather intuitive interface, reduces the execution time of several operations.
4.3. Functionality All the results obtained in this study (Graph 4) correspond to the expected results. Therefore, it can be concluded that both tools obtained the same results without any noticeable lack or loss of quality.
4.4. Time of project implementation Table 3 shows the data obtained from measuring the execution times. The difficulty of identifying the information related to CFs on the cartographic material must be taken into consideration. The large number of lines made it difficult to recognize the boundaries of each forest, and 30% of the execution time was spent in this task. Moreover, the digitizing process and the database connection process required the consultation of the documents and manuals enclosed with the cartographic material, which contained information about the forests. As shown in Table 2, the phase that took longest was the digitizing process. In this particular case, the execution time depended on the expertise of the user to minimize as far as possible the digitizing error. The digitizing process took longer in the case of Geomedia, because alphanumeric data had to be added in this phase. It can be concluded that project implementation consumes less time (-14 hours)
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in Geomedia due to ease of use, especially in the following processes: layout output, DGN import, and digitizing/database (as an integrated task). The estimated total costs per time of implementing this project for the region of Ancares could be easily calculated according to the methodology used. In this case, the main advantage of using GRASS would be the zero cost per hour of GIS software.
From a global perspective, and according to the analyzed data, Table 3 shows the most positive aspects and the least positive aspects of GRASS and Geomedia Professional. Currently, GRASS unstable versions 5.3 and 5.7 (GRASS Development Team 2005a) (Neteler and Mitasova 2004), correct some of the problems that have been mentioned. For example, the mentioned versions include a graphical interface for layout output, more functionalities in the digitizing process and improvements in the DBMS, which includes the MySQL database. With regard to Geomedia Professional, the product segmentation imposed by Intergraph renders this tool more limited as a general GIS.
5 – CONCLUSIONS The main conclusion of this study is that GRASS can cover a larger number of knowledge areas in GIS projects because it works with raster and vector formats, and offers more tools for spatial analysis. Moreover, GRASS is a free, open source tool that enables the user to explore, alter, adapt, or just consult the algorithms, which makes the tool rather flexible. Geomedia Professional is a good vector tool, with a robust graphical interface and, above all, with the innovative concept of GIS/database, which is rather successful. However, Geomedia Professional becomes a limited option for many GIS projects when the functionalities offered by
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Intergraph in the Geomedia package are not incorporated. For example, in this case, the whole project was more oriented to the vector model. GRASS was initially developed as a support tool for the raster model. Conversely, Geomedia Professional was developed based on the vector model. In order to simulate this project with the raster model, this functionality would have to be added to the software by buying Geomedia Grid, which would supply the tools required. From a philosophical perspective, the authors do not defend the concept of license, and consider that all software should be free, regardless of the fact that it may have a cost. Free software shows definite advantages such as the duplication of algorithms or the better quality of the source code. The authors have verified that their initial interest in the issue of proprietary software and free software is completely justified because it agrees with specific concerns that many companies and research organizations must face at present.
REFERENCE LIST DiBona, C. Ockman, S. and Stone, M. Open Sources. Voices from the open source revolution. 1ş ed. O'Reilly; 1999.
GRASS Development Team. GRASS 5.7 Development [Web Page]. Accessed 2005a Jan. Available at: http://grass.itc.it/grass57/index.html. GRASS Development Team. GRASS Documentation [Web Page]. Accessed 2005b Jan. Available at: http://grass.itc.it/gdp/manuals.php. Greve, G. Free Software in Europe. Public Service Review - European Union. 2003 Nov 2; 5th Edition. Halloran, J. and Scherlis, L. High Quality and Open Source Software Practices. Meeting Challenges and Surviing Success. 2nd Workshop on Open Source Software Engineering, ICSE 24; Orlando,
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USA. 2002. Intergraph (José Antonio Rubio). Pregunta Precios actualizados. E-mail to: Rafael Crecente (
[email protected]). 2004 Jan 9. Limp, W. Fredrick and Harmon, D. Inside Geomedia. USA: OnWord Press; 1998. Longley, P. Goodchild, M.; Maguire, D. and Rhind, D. Geographic Information Systems and Science. England: John Wiley & Sons, Ltd; 2001. Neteler, M. and Mitasova, H. Open Source GIS: A GRASS GIS Approach. 1 ed. Kluwer Academic Publishers; 2002. ---. Open Source GIS: A GRASS GIS Approach. 2 ed. Kluwer Academic Publishers; 2004. Wagner, J. FreeGIS [Web Page]. Accessed 2005 Jan. Available at: http://freegis.org/.
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List of figures
Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7
Methodology used to implement the project using Geomedia Professional 5.1 and GRASS 5.0.3 Methodology used in the Import process Methodology used to georeference CF maps Methodology used in the Digitizing process Methodology used in Database connection Result of the spatial analysis performed Result of the layout map process
Figure 1. Methodology used to implement the project using Geomedia Professional 5.1 and GRASS 5.0.3
Figure 2. Methodology used in the Import process
Figure 3. Methodology used to georeference CF maps
Figure 4. Methodology used in the Digitizing process
Figure 5. Methodology used in Database connection
Figure 6. Result of the spatial analysis performed
Figure 7. Result of the layout map process
List of Graphs
Graph 1 Graph 2 Graph 3 Graph 4
Overall average of comparative results Comparative results – Capability in the six phases Comparative results – Ease of use in the six phases Functionality in the six phases
Graph 1. Overall average of comparative results
1
1
1
1 0.83 0.8 0.7 Geomedia Pro
0.5
GRASS
0 Capability
Ease of use
Functionality
Graph 2. Comparative results – Capability in the six phases 1
1
1
0.6
1
1
0.6
1
0.6
1
0.6 Geomedia Pro
Layout
GRASS
Spatial Analysis
Database
Digitizing
Georeferencing
0.4
Importing
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
Graph 3. Comparative results – Ease of use in the six phases 1
1
1 0.8
1
1
0.8
1 0.8
0.6
0.6
0.6 Geomedia Pro
Layout
Spatial Analysis
Database
Digitizing
Georeferencing
GRASS
Importing
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
Graph 4. Comparative results – Functionality in the six phases 1 1
1 1
1 1
1 1
1 1
1 1
Geomedia Pro
Layout
Spatial Analysis
Database
Digitizing
Georeferencing
GRASS
Importing
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
List of tables table 1 table 2 table 3
Characteristics of the municipalities in Ancares Data obtained from measuring execution times in hours General evaluation
Table 1. Characteristics of the municipalities in Ancares Municipality No of Forests Area (ha) Nogales 71 6137 Navia 100 17742 Becerreá 151 9016 Pedradita 49 5906 Cervantes 107 19069 Baralla 47 5704
Table 2. Data obtained from measuring execution times in hours Phases of the Project
Nogales
Navia
Baralla
Becerreá
Pedrafita
G. Pro
GRASS
G. Pro
GRASS
G.Pro
GRASS
G. Pro
GRASS
G. Pro
GRASS
a) Importing b) Georeferencing c) Digitizing d) Database connection e) Spatial analysis f) Layout
0.1 0.5 11 0 0.1 0.1
0.3 1 9 3 0.3 0.25
0.1 0.38 35 0 0.1 0.1
0.4 0.5 30 6 0.3 0.25
0.1 0.45 12 0 0.1 0.1
0.15 1 10 4 0.3 0.25
0.1 1 19 0 0.1 0.1
0.17 1.3 16 6 0.3 0.25
0.1 1 25 0 0.1 0.1
0.2 1.15 22 6 0.3 0.25
Total hours
12
14
36
37
13
16
20
24
26
30
Table 3. General evaluation
Geomedia Professional 5.1
GRASS 5.0.3
Most positive
Least positive
1. Graphical interface 2. Connection to database 3. Capability of vector analysis 4. Many design tools 5. Layout 1. Capability to import and export data 2. Many spatial analysis tools; 3. Open Source, which allows access to all the algorithms 4. Free
1. Capability to import and export data 2. Limited in spatial analysis due to commercial criteria 3. Price. The authors consider that 14,606.72 € (Intergraph 2004)is a high price for a license 1. Rather incomplete and scarcely intuitive graphical interface, which causes slow performance of many options such as layout 2. Few options for database manipulation
