Asst. Prof. in Civil Engg.
Dept. Vasavi College of Engg., Hyderabad
Director, Global Info Sciences,
Agriculture Officer, Dept. of Agriculture
Govt. of Andhra Pradesh, Hyderabad
The capabilities of many Web mapping products in 1999 are different from those available just last year. A major error in selecting a Web mapping solution is in the implicit view that Web mapping is simply an extension of existing enterprise GIS/desktop mapping activities; this is not the case. Web mapping solutions are directed at a different audience than GIS/desktop mapping packages. The level of expertise required, training to be expected and intensity of involvement are much different. This is a key distinction, and Web mapping developers need to keep the user base’s characteristics in mind if a site is to meet its goals.
An essential aspect to view while developing a web based GIS application that the application should not take longer time in displaying both spatial and attribute data over the browser. The application so deployed need to interact or provide the information according to users’ preference and the same time data integrity and security to be maintained. A GIS application developed on ArcView can easily be converted to XML and deployed on any web server, which is readily accessible for users of IE 5.x later. The maps interactively changes its pattern / shape depending on query available on the browser window.
Agriculture Information System provides a new approach to agricultural chemical applications. This approach involves development of tools that will regulate the amount of crop input applied to a field based on the actual need. A key component to this approach is the utilisation of GIS technology. GIS provides the visual integration of all the data sources tied to an agricultural field and allows farmers to identify the within-field variability of their systems. This approach uses GIS to incorporate spatial information such as soil type, type of crop, and existing nutrient level of the soil with the agricultural chemical application process. The addition of spatial information to the process allows the farmer to consider within-field variation to adjust the amount of chemicals that are being applied based on what is actually needed at the sub field level.
Geographical Information System (GIS) is an information system that is specially designed for handling spatial (or geographical) data. It combines a set of interrelated software components that create, edit, manipulate, analyse and display data both in text and graphic forms. GIS supports spatial analysis and modeling within the discipline of geography (e.g. location, proximity and spatial distribution), so that it becomes a vital tool for modern geography.
Web GIS is a geographic information system providing environmental, social economic and geographic information using technologies though the Internet. This technology has evolved to provide citizens and activists with a tool allowing people to overlay data layers and understanding possible relationships between them. One of the more confusing aspects to selecting the best Web mapping product is that everything is interlocked. For example, the speed of the Internet connection affects the amount of data transferred; the type of data also affects transfer volumes, which, in turn, also influences the speed, etc.
Fig 1: Agriculture Information of Mahaboob Nagar District on IE 5.0 Browser
AxioMap (Applications of XML for Interactive Online MAPping) is a software package for publishing and viewing interactive maps on the World Wide Web. It is based on XML, the eXtensible Markup Language, and an emerging standard for data interchange on the Internet. It can be used as on of the extensions of ArcView 3.x or later to allow quick and easy conversion of ArcView projects into a series of XML files with map information and an interactive map viewer that can display, in IE 5.x or later Web browser, map information retrieved from these XML files.
Land is an indispensable resource for the most essential human activities: it provides the basis for agriculture and forest production, water catchments, recreation, and settlement. The characterisation of land resources includes components of climate, soils, landform, and present land cover. Adequate agricultural exploitation of the climatic potentials and maintenance of land productivity largely depend on soil fertility and the management of soils on an ecologically sustained basis. The composition of soil associations is described in terms of percentage occurrence of soil units, soil phases and textures. The digital soil information constitutes part of the land resources database and is kept together with other geographic information (i.e., elevation, terrain slopes, distance to coast, protected areas, land cover, and administrative divisions).
To generate thematic maps automatically that correctly and effectively present map based visualisations of geo-data sets selected by the user.
To provide all necessary user interactivity while requiring no special software to be installed on the user’s side except IE 5.x or later Web browser.
To provide remote, prompt and effortless access to remote Agriculture Information at district level through the WWW.
Location and Extent
The agriculture information system for Mahaboob Nagar is selected as the location for development of Interactive Online Mapping with XML. The available extent of this district is covering Latitude 150 50′ to 170 15′ N and Longitude 770 15′ to 790 15′ E. This district is having very moderate rainfall and also experiencing the low yield of agriculture.
The periodic observation of chemical constituents of cultivated land and developing Agriculture Chemical map to aide the Agriculture Department for suggesting suitable crop practices and management. The changes in the chemical constituents of farms and nutrient levels which helps in healthy growth of crops, if properly monitored then proper proportions of fertilizers can be decided for effective crop output.
The input required for developing agriculture information system at District level were Topography sheets covering entire District in the scale of 1: 250,000. The Department of Agriculture, Hyderabad AP, has conducted soil-sampling surveys for the entire District of Mahaboob Nagar considering various parameters both physical (soil depth, irrigability, texture and land capability), nutrient availability (nitrogen, potassium, phosphorous, Iron and Zinc) and soil solution.
The data pertaining to the parameters together with geographic features were obtained from Department of Agriculture. The broad classifications of these thematic data are provided to produce a small-scale map. The expected output from this Agriculture Information System would help the decision makers or farmers to cultivate suitable crop type, crop rotation and cropping pattern together with proper composition of fertilizers, pesticides and other chemical compounds to achieve the healthy growth of agricultural products.
Agriculture is one of the oldest industries. Late 1600’s inventors began to develop machinery for planting, cultivating and harvesting crops. During 1800’s Scientists began to identify the chemicals that crops need to grow, for ex: legumes are useful for crops rotation, because the plants incorporate atmospheric Nitrogen into the soil. Scientists also identified other elements that crops need such as Phosphorous and Potassium. During 1900’s Scientists have developed better stronger varieties of plants and livestock and highly effective fertilizers and pesticides.
Fig 2 – 5: Some of the Thematic maps Developed in ArcView
Texture of the soil depends on the size of mineral particles. Sands are the largest particles. The individual grains can be seen and felt. Silts are just large enough to be seen and Clays are microscopic. Pedologists divide soils into textural classes according to the amount of Sand, Silt and Clay. For example: The mineral portions of soils classified as loam contains from 7 to 27% of Clay and less than 52% of Sand, in SiltyClay more than 40% Clay and more than 40% of Silt. Texture helps determine how thoroughly the water drains from a soil. Sands promote drainage better than clays.
These are required in bulk quantities for healthy growth of plants,
Nitrogen: It is integral component of many compounds, including chlorophyll and enzymes, essential for plant growth processes. Nitrogen can acidify the soil as it is oxidized.
Phosphorous: Phosphorous is essential for plant growth and involved in most significant energy transformation. The amount of Phosphorous in the available form at one time is very low.
Potassium: It is an activator of enzymes responsible for energy metabolism, starch synthesis, nitrate reduction and sugar degradation. Potassium exerts balancing effect on the elements Nitrogen and Phosphorous.
Seventeen elements are known to be essential for plant growth, of which eight are required for very small quantities called micronutrients or trace elements. These are Iron, Manganese, Zinc, Copper, Boron, Molybdenum, Cobalt and Chlorine.
Zinc: It plays a role in protein synthesis, in the formation of growth hormones and in the reproductive process of certain plants. It promotes seed maturation and production.
Iron: It is found in several peraoxidises, and ferredoxine which participates in oxidation / reduction reactions (Nitrate and Sulphate reduction). It is also important in chlorophyll formation.
GIS integrates spatial and other kinds of information within a single system. It offers a consistent framework for analysing geographical data. By putting maps and other kinds of spatial information into digital forms, GIS allows us to manipulate and display geographical knowledge in new and more objective ways. Spatial data consist of digital representations of discrete (spatial) objects. The contents of a map can be captured in a database by turning map features into data base objects.
Tools for Agriculture Information
The introduction of ArcView GIS Version 3.0 offers a very powerful tool to global agriculturists. ArcView GIS Version 3.0 lets the user combine vector and raster data for analysis, which makes it an excellent front-end tool in site-specific agriculture and agricultural research. The field desktop GIS sites can be considered as a frame that contains data related to the research fields.
Preparing ArcView project for Publishing on the web
The AxioMap (Applications of XML for Interactive Online MAPping) runs with ArcView extension, it is suggested to work on ArcView 3.0 or later on any platform, since ArcView extensions are platform-independent. It has been tested the extension on ArcView 3.1 running under Windows 95/98/NT.
AxioMap utilises new vector graphics technology that is just being implemented in Internet viewing software; maps created in this manner must be viewed in Internet Explorer version 5 and above, with the VML (Vector Markup Language) option installed (it installs by default).
Before converting the ArcView themes to XML, it is necessary to make sure all attribute data need to be displayed are joined to the feature table. An additional column in feature table is the column with object names (labels) to be added. In AxioMap viewer, when a mouse pointer placed over any object, the content of this field is displayed. It is recommend that a column with object names (labels) in feature tables for each of the themes that are converted for the Web.
A new AxioMap map is started after making a new directory where all newly created map files will be stored. AxioMap will be converting each map layer into individual XML files, by selecting conversion scripts from the AxioMap pull-down menu. The conversion results are not ‘written in stone’ – the changes of certain parameters in any XML file after the conversion are possible.
These conversion scripts begin with Base theme, AxioMap creates layers.xml, a.xml and g.js files in the selected folder and the files are written by the conversion script into .xml files. The themes in ArcView required to be opened as .shp files, the scripts in AxioMap supports only .shp files for conversion to XML files.
While reading a file from a remote server into the AxioMap map, one needs to enable data access across domains in Internet Explorer 5. From the IE5 pull-down menu, select Tools – Internet Options – Security – Custom Level. Scroll down to “Miscellaneous” and Enable “Access data sources across domains” (by default, this option is disabled).
To publish desired map(s) on the Internet/Intranet, simply upload map folder (or several folders) along with the axiom folder, to a web server. The axiom folder, and folders containing all maps, is next to each other on the same level of hierarchy.
To publish the application on the web, a URL consisting main.htm loads the AxioMap viewer with the base theme selected. This viewer consists two frames, left frame is utilised for Map navigation, and right panel is used for presenting map.
Development of Agriculture Information
The thematic mapping of the soil characteristics such as Land capability, Soil depth, Land irrigability, Soil texture and Agriculture chemical thematic maps such as soil solution, nutrient status such as macronutrients (Nitrogen, Phosphorous and Potassium) micronutrients (Zinc and Iron) were obtained from Department of Agriculture. Hyderabad, AP. The attribute data pertaining to all the parameters were also obtained for integration with the spatial (thematic) data.
The topographical sheets in the scale of 1; 250,000 with the indexes numbering 56 G, 56 H, 56 K, 56 L, 56 P, 57 E and 57 I were obtained from Survey of India. These maps were scanned using DeskPro scanner in a single view, later saved as JPEG file. The images were available in Raster format.
The image in the raster format is imported to AutoCAD software; p-line (poly-line) function available in the software is utilised for converting the raster format to vector format. The vector format of the image in the AutoCAD is saved as a .dwg file. This file was transformed to convert the .dwg file to .dfx format; this is suitable for importing the data into PC – Arc/Info. Errors were eliminated in the case of over-shooting, under-shooting of the lines and also the spikes caused during digitisation process with the help of editing functions. Clean and build commands or functions were run on this file to build topology: hence the relationships of the spatial data types were established.
Fig 6: The AxioMap 0.9 extension pull-down menu in ArcView
Creation of Spatial Data
The digital database of the Mahboob Nagar was created after performing the editing operations. The geographic locations of the Mandal divisions were of type nominal data comprising point data corresponding table was point attribute table. Division boundaries were classified as polygons. The adjacency relationships for 15 Mandal divisions were established for all division boundaries. The software creates Arc Attribute Table, Polygon Attribute Table and Point Attribute Table. The data was exported to generate .e00 format to enable the file to import into ArcView.
All the spatial data for the purpose of Agricultural Information were scanned, digitised and built to generate topology as explained earlier. Storage Media The disk drive for the map generator was taken necessary care in order have sufficient space to hold input and output data for the predetermined locations.
Creation of Database Model
The database files that were generated to be classified according to the range and extent of the characteristics of parameters. The attribute data required to be integrated with the spatial data, for developing a well-versed GIS model. The Department of Agriculture had collected the all types of attribute data, and classified the attribute data by grouping the values. The characteristic features of spatial data linked to the spatial or geographical locations of the District map.
Suggested Land Use
The suggested land use of Mahaboob Nagar district was classified into different cropping system based on the agriculture chemical and soil characteristic mappings. The thematic mapping of suggested land use practices are described below:
Agri – horty – Silvi pastoral system
Agro forestry – based plantation system
Cotton based cropping system
Minor millets based cropping system
Rice – based cropping system
Sorghum – based cropping system in black soils
Sorghum – castor cropping system (red soil region)
Groundnut – based cropping system
The Axiomap extension was selected from the file menu and the extension was checked in order to generate .xml files. AxioMap would be added to the menu list of ArcView window. The scripts in the AxioMap were chosen in the order beginning with Base Theme. The script prompts for each execution of the selected commands. The Base Theme of Mahaboob Nagar with only district boundary was selected to convert the file into .xml file.
AxioMap layers of different types were created as XML file by invoking a corresponding menu item from the AxioMap 0.9 extension pull-down menu and running an associated script. The pull-down menu was shown in the fig.6
To create a multi-layer map, ArcView layers were converted to XML by running the sequence of scripts in the ArcView extension, starting from the “Base Theme” and ending with “Finish”. Only the base map layer is mandatory, and need to run at least the “Base Theme” script. Creating all other layers is optional. In all cases, later finish the map by running the “Finish” script.
The Agriculture Information System that was developed in .xml files is very useful for the decision makers, agriculture Department and farmers or any others who require nutritional and other soil characteristics. The main advantage with the converted ArcView project to .xml would facilitate the users of this information need not possess any GIS skills or exposure.
The district is consistently affected with insufficient rainfall, together with lack of requisite Agricultural nutrients for healthy growth of plants or farm practices. Nitrogen availability that is important crop nutrient moderately exists in the many parts of the district, Phosphorous availability exceeding 90% of the district area is observed as Low and Potassium exceeding 50% of the area is observed as Moderate. Combining all the parameters both soil characteristics and Agriculture Chemical mapping specific areas for the cultivation of crops such as cotton, groundnut, rice, millets and agro forestry are mainly suggested.
The following constraints were observed with development of Interactive Online Mapping with XML.
- The application can be viewed or seen on Internet Explorer 5.x or later.
- The present AxioMap ver. 0.9 has not supported the relationship of polygon islands.
- The bandwidth available for web server is very important for speedy access of the application.
The dynamic variation of the soil nutrients needs to be monitored and suggestive fertilizers or pesticides for optimum crop yield, a large scale mapping of the same would be beneficial. The same information could be further made divided into smaller grids and task controllers are fed with the all-chemical information. Task controller map production in the precision agriculture system can be divided into five main functional tasks and are considered in this section. The first step is a preprocessing step. It involves the inventory and processing of source materials required to formulate the task controller maps. The second step involves the actual map generations. We have further separated map generation into automated map generation and manual delineation. Although there is no limitation constraining the geographic coverage and details of the source materials, the output task controller maps are governed by their operational parameters and the requirements of the field task controller. Generally, each task controller map is applicable for one precision applicator machine.
After the application maps are generated, there is a review and manual adjustments tasks—the third step. After review and subsequent adjustments, the maps are exported in a suitable format for transmission to the task controller—the fourth step. Finally, the map generation component of the precision agriculture system also maintains a feedback mechanism. The fifth step involves importing status reports or summaries from the task controller and integrating the operations reports into the map generator database.
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- Application of XML for Interactive Online Mapping: AxioMap 0.9 Web map publishing and viewing program.
- Global Agro-Ecological Zones (GAEZ) system – Food and Agriculture Organisation