DEVELOPMENT OF GPS PHOTOS DATABASE FOR LAND USE AND LAND COVER APPLICATIONS An Ngoc VAN and Wataru TAKEUCHI Institute of Industrial Science University of Tokyo 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 Japan Tel: (81)-3-5452-6407 Fax: (81)-3-5452-6408 E-mail: vanan@iis.u-tokyo.ac.jp KEY WORDS: Land use, land cover, GPS, GPS Photo Database, Mobile ABSTRACT: In land use and land cover applications, it is very important to validate the result by using the ground survey data, which is collected in the field trips. A lot of ground survey data are existing at many research institutions and normally include the photos, longitudes, latitudes, altitudes, land cover types and other information of the places of interest. However, that data often was not well organized as a database in order to be effectively used by computer software. For this reason, this study develops a method to build up a GPS Photos Database from the ground survey data. In this study, the ground survey data are processed to extracted the necessary information and combined in to a database including the pictures of the investigated places coming along with the corresponding latitudes and longitudes, land cover types and descriptions. An application on iphone was also developed to make it easier and quicker to add new data to the database. This database has been using for validating the classification result of the forest management projects in Vietnam and Laos. It is expected to be a large GPS Photos database which is updated frequently by the research institutions in the Asian countries and provides useful information for the land use and land cover applications. 1. INTRODUCTION In land use and land cover applications, it is very important to validate the classification result by using the ground survey data, which is the geographical information of the place of interest. A lot of ground survey data sources are existing at many research institutions or on the internet, and normally include the name, photo, longitude, latitude, altitude, land cover type and other information of the places of interest such as address, population, average elevation, time zone With the ground survey data collected by research institutions, because the researchers only use those data for their particular purposes, the ground survey data were often not well organized as a database in order to be effectively accessed by the computer software. With the ground survey data sources on the internet, data is organized as a database containing various types of information, which can be used for many other types of application. However, in the land use and land cover applications, user does not use all of the information provided by those databases to calibrate his result, and therefore, the user has to build his own interface to extract only the information he needs (GeoNames Services, 2007)(Alexandria Services, 2004). For these reasons, in this study, a GPS Photos Database for land use and land cover application from the ground survey data is developed. GPS Photos Database is built up based on the ground survey data existing at the research institutions. With this database, researchers can easily access to the necessary information to validate the results of land use and land cover applications. By using the application on computer and mobile device, researchers can also quickly add new data to enrich the database.
2. EXISTING DATA SOURCES There are two types of ground survey data sources: the data sources at the research institutions, which is collected by the researchers, and the data sources on the internet, which is built up by some research projects and updated by many users from all over the world. 2.1 Data sources at the research institutions The ground survey data at the research institutions are often collected from the field by the researchers. Because these data are used only for some specific purposes, such as forest cover mapping or land use monitoring, only the necessary data are considered and collected. For example, in order to calibrate the forest cover mapping applications, the researchers will collect the data relating to the forest types at the selected locations, which includes name, time, longitude, latitude, altitude, and land cover type; they will not collect other data such as population, average elevation... After collecting, all those data will be stored in the format of the very simple tables (rows and columns), which are often difficult to be directly used by computer software. Thus, the researchers have to spend a lot time to process the collected data and manually convert those data to the suitable format for computer software. Furthermore, because the collected data are not well organized as a database, to manage a large amount of ground survey data (storing, searching, updating, combining ) is a very big problem. For these reasons, the solution to use more effectively the ground survey data at the research institutions is to build up the databases of ground survey data. 2.2 Data sources on the internet GeoNames (GeoNames, 2007) and Alexandria (Alexandria, 2004) is the two largest geographical databases on the internet (Popescu, A. et al., 2009) (Ling Y., 2003) (Greg J. et al., 2004). The GeoNames geographical database is available for download free of charge through a number of web services and a daily database export. It contains over eight million geographical names and consists of 7 million unique features. Similar to GeoNames, Alexandria provides a federated spatially searchable digital library of geographically referenced materials. The library's components are distributed (spread across the internet) or coexist within a single network or desktop. Both GeoNames and Alexandria are integrating geographical data such as names of places, GPS coordinates, elevation, population and others from various sources. However, because GeoNames and Alexandria provide data for various types of application, these data sources including a lot of information which are not used in the land use and land cover applications; thus, the users need to set up their own interface to extract the necessary data. Furthermore, in these data sources, the users often update the information of the easy-to-access places such as cities or tourist spots, while the ground survey data of the remote areas, where usually are hard to access, are very essential in land use land cover applications. 3. GPS PHOTOS DATABASE 3.1 GPS Photos Database in land use and land cover application Figure 1 is the diagram of a land use land cover application. In this figure, input data is the imagery data of the place of interest. The input data is processed to produce the draft result. This draft result is then validated by using the ground survey data in GPS Photos Database. The output of validating step is final result. In this situation, the ground survey data in GPS Photos Database is very important, because it is one of the factors to make the final result more accurate. The more data the GPS Photos Database has, the better the final result is.
3.2 Structure of GPS Photo Database Figure 1. Diagram of a land use land cover application GPS Photos Database is created from the records. Every record contains the information about one place. It includes a name, a photo, a longitude, a latitude, an altitude, a land cover type and a description. Figure 2 is a content of a record in GPS Photos Database. Figure 2. Content of a record in GPS Photos Database The name of the record is used to specify a unique record in GPS Photos Database. It consists of the name of the photo, acquisition time, latitude, longitude and altitude of the place of interest. For example, in figure 2, the name of this record is DSC73_GPSPHOTO20100411N2146E10673A0000.JPG, which means that the name of the photo is DSC73, it was taken in November 11, 2010 (20100411), at latitude 21.46 o North, longitude 106.73 o East, and the altitude at the camera s position is 212m. IGBP land cover classes 00 Water 01 Evergreen Needleleaf Forest 02 Evergreen Broadleaf Forest 03 Deciduous Needleleaf Forest 04 Deciduous Broadleaf Forest 05 Mixed Forest 06 Closed Shrubland 07 Open Shrubland 08 Woody Savanna 09 Savanna 10 Grassland 11 Permanent Wetland 12 Cropland 13 Urban and Built-up 14 Cropland/Natural Vegetation Mosaic 15 Snow and Ice 16 Barren or Sparsely Vegetated Table 1. IGBP land cover classes In GPS Photos Database, the definition of land cover types are followed the International Geosphere-Biosphere Programme (IGBP, 2006). According to IBGP, land cover type is
classified into 17 classes as in Table 1. The land cover type is expressed by the corresponding IGBP ID. In order to store more information about the place of interest, beside a photo attached with each record, the Description field is also added. User can make the description to describe in more detail the place his took picture to exactly specify the land cover type not only at the acquisition time but also in the future. For example, user can list the main species or point out the time when the leaves start falling down, which can be used to predict the status of that place in a particular time in the future. 3.3 Adding record to GPS Photo Database Figure 3 described how to add a new record to GPS Photos Database. At the first step, the data is collected at the field by taking photo as well as specifying the latitude, longitude and altitude of the place of interest. Latitude, longitude and altitude are measured by using the corresponding measurement devices. Altitude value can be 0 if there is no altitude data available. Figure 3. Adding a record to GPS Photos Database In the next step, GPS information including latitude, longitude and altitude is added to the image file by using EXIF (Exchangeable Image file Format) editor software. Windows users can use EXIF Pilot software (EXIF Pilot, 2003), Linux and Mac users can use EXIFutils (EXIFutils, 2003), which are free EXIF editor software. Nowadays, some types of digital camera with GPS function can take photo with latitude and longitude values embedded into the header of the photo. After getting the photos with GPS information embedded, user needs to specify the land cover type and make description for the place of interest. In order to select the land cover type, the names and GPS information (latitude, longitude, altitude) in the photos are extracted to a text file; in this file, user can select an IGBP ID to specify the land cover type, user can also make the description to give more information.
At the last step, the new records are added into the GPS Photos Database. Figure 4 is a part of the database. The placemarks show the places where the data were collected. At every placemark, the information including photo, latitude, longitude, altitude, IGBP ID and description is displayed. Figure 4. GPS Photos Database in Google Earth 4. GPS PHOTOS APPLICATION ON IPHONE Normally, after taking the photo at the field, user needs to edit information (adding GPS information, specifying IGBP ID, making description) before adding the new records to the database. However, since the user often takes many photos at many different places, and even sometimes it is difficult to bring the computer with him to some places, it will take a long time to edit information at his office. For this reason, an application on mobile devices, which allows user to take photo, edit information and add new records to the database, would help users to significantly reduce editing time as well as easily and quickly enlarge GPS Photos Database. Nowadays, iphone (iphone, 2009) is one of the most widely used mobile phones in the world. By using iphone, user not only can take photo, get GPS information but also can install new applications on it. Therefore, in this study, an application named GPS Photo is developed for iphone. GPS Photo application on iphone helps user to take the photo, automatically retrieve latitude and longitude, edit altitude value, select land cover type based on IGBP classes and make description. And if iphone is connected to internet by using wifi or 3G network, user can also add new records to GPS Photos Database at server from GPS Photo application. Figure 5 is the interfaces of GPS Photo application. The current GPS Photos Database on iphone with photos, land cover types, longitudes and latitudes is displayed in figure 5a. When user selects a photo, the information relating to that photo will be shown as in the figure 5b. Latitude and longitude values are measure automatically by iphone. User can change value of latitude, longitude and altitude as in figure 5c, select land cover type as in figure 5d, and make description as in figure 5e.
(a) (b) (c) (d) Figure 5. GPS Photo application on iphone (e) 5. CONCLUSION This study developed a GPS Photos Database for land use and lover application by collecting ground survey data at the research institutions and organizing them as a database. The land cover types are specified based on the IGBP land cover classes. The current GPS Photos Database was stored on the server in Institute of Industrial Science, University of Tokyo, Japan and contains thousands of records. Those records are ground survey data collected from September 2009 to April 2010 in Bac Giang, Lang Son, Dak Lak, Dak Nong provinces of Vietnam as well as in Khammouane, Luang Namtha and Bolikhamxay provinces of Laos. The researchers at Remote Sensing Center of Laos were also trained to add new records from their ground survey data to the GPS Photos Database. GPS Photos Database has been using to validate the result in the land cover classification projects in Vietnam and Laos. In the future, with GPS Photo application on iphone and other mobile devices, GSP Photos Database will be updated frequently and enlarged quickly by many people from many places. To build up an interface in order to extract necessary geographical information from the data sources from internet such as GeoNames and Alexandria will also make the content of GPS Photos Database richer. 6. REFERENCES Alexandria, 2004. Alexandria Digital Library. Website http://www.alexandria.ucsb.edu/adl/ Alexandria Services, 2004. Alexandria Digital Library Search Query. Website: http://clients.alexandria.ucsb.edu/gt_help/index.php EXIF Pilot, 2003. EXIF Editor software. Website: http://exifpilot.com/ EXIFutils, 2003. EXIF Editor Software. Website: http://www.digital-photo-software-guide.com/exif-editor.html GeoNames, 2007. GeoNames geographical database. Website: http://www.geonames.org GeoNames Services, 2007. GeoNames Web Services Documentation. Website: http://www.geonames.org/export/web-services.html Greg J. et al., 2004. Issues in Georeferenced Digital Libraries. In: D-Lib Magazine,Vol.10, No.5. IGBP, 2006. International Geosphere-Biosphere Programme. Website: http://www.igbp.net/page.php?pid=250 iphone, 2009. Apple iphone. Website http://www.apple.com/iphone/ Popescu, A. et al, 2009. Mining a Multilingual Geographical Gazetteer from the Web. In: International Conference Web Intelligence and Intelligent Agent Technology, pp. 58-65. Ying L., 2003. Geo-referenced Digital Libraries: Experienced Problems of Purpose and Infrastructure. In: Library Philosophy and Practice, Vol. 6, No. 1.