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Computerised Cadastral Mapping: A Modern Technological Improvisation
R. M. Singh
National Centre for Human Settlements and Environment, Bhopal
E-mail : rrmsingh@rediffmail.com
Introduction
Applications of cartography in rural mapping are age old and this art has taken various turns since from its existence till today. The new trends in cartographic development has endeavor this art with digital techniques. The making and use of computer based systems for the cartography is added advantage in reproduction and multidisciplinary use and analysis of thematic mapping in the rural development activities. In fact this transition to "computer cartography" started long time ago. It is worth noting, however, that the pace of change towards an electronic future is variable across the world. Digital cadastral maps are being produces as cartographic maps, which provide an overview of some of the major trends and concerns in digital cartography. The paper is attributed the contribution of applications of CAD (Computer Aided Drafting) in digital cartography in addition to Geographical Information Systems applications for thematic mapping through digital analysis. Digital cadastral maps are used as a media for generating and preparation query cell for rural planning as well.
Every activity needs proper planning, reporting and monitoring. A well-formed information base is most essential for support during these processes. The graphical form of data is most easily understood at any level of functionary and is most properly interpreted, and useful actions can be followed.
As far as storage and processing of information is concerned, computers are already quite accepted tool. Computers mainly help in storing information in the form of maps and help the user in performing complex tasks in such simplified way. Sketchy maps and illustrations used to record land ownership and revenue information in India, later gave rise to cadastral maps. Assessment of crop yield and fixing the governmental share became a major activity of revenue administration. Scale alteration and superimposition are hard exercises if one is working with printed maps (on paper), but the same are easily performed through digital maps.
Beginning in the 1970's, many mapping experts adopted a communications model for cartography, understanding maps as tools for the communication of information from cartographer to map user. With the rapid progress in computer technology afforded by the ubiquitous personal computer, in the last decade a number of cartographic researchers, led by Alan MacEachren (1995), have suggested a new way of understanding how maps work. Rather than attempting to make a best map, modern computer technology can allow for the preparation of multiple representations of a phenomenon that can be used to answer different questions.
High-resolution digital data (satellite image / aerial photographs) can be used for capturing the individual land holdings. It also aids in easy retrieval and manipulation of data, to update new land parcels to enable periodic report generation and its changing pattern.
Objectives
Objectives of this paper is to highlight the needs of the digital cadastral mapping with cadastral information at larger scales for physical planning and development of rural areas and to drive the such need to the survey and mapping community.
Use of large-scale cadastral maps
Preparation and use of large-scale maps, especially for rural areas, is not as good as in developed and other developing countries (Rudraiah). Maps are required by many department, NGOs, agencies, companies to carry out developmental activities in the area. Local authorities, public undertakings, service organisation require maps. However, the requirement of maps in terms of quantity, quality and accuracy vary from organisation to organisation. It is important to note that all the agencies aforementioned and others do not need comprehensive map, i.e. all the information in map.
Need For Computerised Village Maps
Cartographers use methods of showing objects on maps in various ways- for example symbols or objects, lines, hatching boundaries etc. Usually separate maps are created for different subjects or themes, thus, giving rise to numerous maps of the same area. Since in most cases these maps are produced by different agencies using no common methodology, the scales of these maps are also quite different. Computerised maps comes very handy for these initial stages of mapping and prove much more useful when mapped data is put to use. Computerised maps allow mapping of details and minor alterations wherever required. The selected superimposition of selected themes gives idea of an integrated picture and helps to understand area by considering variety of features together.
Lacunae in Existing Cadastral Maps
Exhaustive information is available but hardly used. The information collected from the revenue departments is exhaustive but not used at par. This ignores the logical information principle that as far as possible collection of information should be avoided if it is not going to be used. Further, a number of registers need to be unnecessarily maintaining the auxiliary information. Hard print cadastral maps are not easily available for planning process and area away from the reach of common people. Such maps are only the property of government authority and are used as desired by them.
Development in Digital Cartography
The move towards automation has necessitated some redesigning of maps by eliminating some content (Hadley, 1987) and modifications of others like the conventional hatching replaced by coloured filling of specific symbol.
Simplification of information and graphic design are often undertaken simultaneously in manual generalisation, in digital cartography there is a need to distinguish between information generalisation and display generalisation; the former contributes to digital mapping, the latter to visual mapping. Both types of transformations are intellectually demanding and involve a variety of subtasks and processes. Many applications use maps of the same entities compiled at a variety of scales with different content and symbolism. Many land information systems focus on the land parcel and are concerned with the areal extent of such linear objects. A number of users, such as in local government and NGOs, need both detailed and simplified representations of the same objects. At present, scale-related requirements are met by multiple definitions of the same areas. The scale of display appropriate for each feature is also recorded within a scale-integrated database. Systems based on raster/video images zoom by retrieving images captured at the next larger scale. Other researchers are manually integrating road networks captured at different scales for route planning and are investigating database designs for supporting scale-free mapping (Abraham, 1989). The digital mapping has completely transformed cartography since the mid 1980s where map output in fast multiple reproduction made easier.
Methodology
Monitoring is exercised to make a definite assessment of results of actions and activities and there by decide if any change required. Monitoring through digital maps is very effective and useful. By pointing initial and current status on maps the impact area may be easily seen. Creating maps, union, intersection, subtraction and analyses are easily carried out.
Computerization: There is a considerable effort in culling out the information from the registers to prepare reports in the current manual system. The load of processing/calculation is currently placed on lower staff to maintain documents. The objective is to map out land parcel wise basic indicators / vital statistics. It is envisaged that all data would be computerised and presented in a visual form on a digitised map.
After the initial exercise, including necessary amendments to methodology; it is decided to undertake the task for cadastral mapping. The mapping involved the following two processes being undertaken simultaneously:
Computerised digitization of maps and data is undertaken using cadastral maps basic data like land parcel size, ownership, landuse, cropping pattern and infrastructure details obtained from the “Patwari” as a base. Basic physical features, boundaries and important landmarks were digitized. Other primary baseline and temporal data collected entered in computer system the formulate database.
Cadastral Mapping
Village Khasra (Cadastral) map is very vital and important because it carries the smallest ever mapped land unit in it. The villagers use the maps for general observation at village level and useful for macro level application. Cadastral maps are generally available on 1:6000 or 1:4000 scales. The cadastral maps are consists of all three types of geometries, i.e. point, line and area (polygon). In GIS based cadastral maps all the characteristics like geometry, attribute and map objects are present.
The cadastral maps are generalized form of real earth features on a paper, which involves the application of processes, such as selection, classification, simplification, symbolization and pattern recognition. All cadastral maps are symbolic and rely on the use of a graphic sign language. All the feature, linear and aerial, are demarcated at real scale and area and length of the linear features such as roads and rivers marked by solid double lines can be measures with accuracy due to large scale mapping. While in small scale mapping, such as topographical maps show lengths of linear feature on its scale but areas of most linear features such as roads, railways and single line drainage are as representatives only (Singh, 2005). The design of the symbolization system and of its structure is been based on different parameters. For example, one well within the cadastral map is shown as a small circle, and further qualitative differentiation, based on the lined and unlined well, is also made possible using different patterns of circle.
Cadastral Resource Mapping:
Present important resources available at land parcel level can be considered real perspective for planning purpose. A village resource map gives a useful scenario of the present available facilities & resources, which helps in identification of further required facilities. Therefore, cadastral map used for resource mapping. Figure below shows the characteristics of a digital cadastral map:
Figure-1: Map Characteristics
Cadastral Database
A database is useless unless populated with appropriate data and kept up to date with temporal changes. Digital mapping has a strong capacity to integrate and cover the full range of data sources. The database structure with special reference to Madhya Pradesh cadastral maps can have following records, which are to be constantly updated (Singh, 2005). The record of each map includes information about its:
Components of Digital of Cadastral Maps
The digital cartography involves many components to be decided at first hand. Following the major components are used in it:
Map Layers
The layers can be assigned them to different objects in the map to identify different objects easily. Different layers can be assigned different colors and line types. The layers can control the visibility, color and line type of the objects on a layer for editing and analysis. One object can be moved from one layer to another and even one can change the name of a layer. Layers are the different overlays used in paper-based drafting. The layers are the primary organizational tools in the CAD.
Figure-2: Cadastral Layers, colours and line types
The maximum possible number of layers in a cadastral map could be as much as shown in the figure-2. We can assign a name to each layer and select any combination of layers for display.
Symbolization
Symbolization is the science of signs assigned to particular function, with sign considered to be a relationship between an expression and its referent. For cartography, maps can be viewed as tools to communicate meaning primarily through symbols. This implies that there must be a cartographic language based on symbols that provides a map with meaning. Symbolization is most important part of cartography. In the present paper a rich combination of colour, pattern, shape and size of symbols (Figure-3) is provided according to their functions for defining and applying symbolization styles to point, line, or area data. In digital cartography vector and bit mapped symbols are used.
List of symbols
Figure-3: Map Symbols
Apart from the identification of symbolic feature following parameters plays an important role in symbolization process:
Digital cartography has significant capabilities for text labeling. Many text font types are now supporting it. Font information can now be embedded in output formats. There are numerous capabilities for storing text in the database as annotations. Annotations are well liked with different font formats so that they can be automatically updated as change happens in the real world. Annotation support now includes such cartographic elements as callouts and leader lines. The fonts provide the cartographer with the freedom to override the strict rules of the font selection.
The stored representation capabilities of geo database facilitate to derive, create, and store cartographic features as layers of points, lines, or polygons. Such cartographic feature classes are often vital to the implementation of digital cartographic models from digital landscape models and can act as a source for subsequent stored representations.
Conclusion
Based on the requirement of different departments and NGOs and approval of authorities extensibility of digital cadastral mapping can be provided to make the Land Records easy to use. Thus, creating a transparent administrative environment. Most State Land Records Departments could use the methodology to make it usual practice.
References
Applications of cartography in rural mapping are age old and this art has taken various turns since from its existence till today. The new trends in cartographic development has endeavor this art with digital techniques. The making and use of computer based systems for the cartography is added advantage in reproduction and multidisciplinary use and analysis of thematic mapping in the rural development activities. In fact this transition to "computer cartography" started long time ago. It is worth noting, however, that the pace of change towards an electronic future is variable across the world. Digital cadastral maps are being produces as cartographic maps, which provide an overview of some of the major trends and concerns in digital cartography. The paper is attributed the contribution of applications of CAD (Computer Aided Drafting) in digital cartography in addition to Geographical Information Systems applications for thematic mapping through digital analysis. Digital cadastral maps are used as a media for generating and preparation query cell for rural planning as well.
Every activity needs proper planning, reporting and monitoring. A well-formed information base is most essential for support during these processes. The graphical form of data is most easily understood at any level of functionary and is most properly interpreted, and useful actions can be followed.
As far as storage and processing of information is concerned, computers are already quite accepted tool. Computers mainly help in storing information in the form of maps and help the user in performing complex tasks in such simplified way. Sketchy maps and illustrations used to record land ownership and revenue information in India, later gave rise to cadastral maps. Assessment of crop yield and fixing the governmental share became a major activity of revenue administration. Scale alteration and superimposition are hard exercises if one is working with printed maps (on paper), but the same are easily performed through digital maps.
Beginning in the 1970's, many mapping experts adopted a communications model for cartography, understanding maps as tools for the communication of information from cartographer to map user. With the rapid progress in computer technology afforded by the ubiquitous personal computer, in the last decade a number of cartographic researchers, led by Alan MacEachren (1995), have suggested a new way of understanding how maps work. Rather than attempting to make a best map, modern computer technology can allow for the preparation of multiple representations of a phenomenon that can be used to answer different questions.
High-resolution digital data (satellite image / aerial photographs) can be used for capturing the individual land holdings. It also aids in easy retrieval and manipulation of data, to update new land parcels to enable periodic report generation and its changing pattern.
Objectives
Objectives of this paper is to highlight the needs of the digital cadastral mapping with cadastral information at larger scales for physical planning and development of rural areas and to drive the such need to the survey and mapping community.
Use of large-scale cadastral maps
Preparation and use of large-scale maps, especially for rural areas, is not as good as in developed and other developing countries (Rudraiah). Maps are required by many department, NGOs, agencies, companies to carry out developmental activities in the area. Local authorities, public undertakings, service organisation require maps. However, the requirement of maps in terms of quantity, quality and accuracy vary from organisation to organisation. It is important to note that all the agencies aforementioned and others do not need comprehensive map, i.e. all the information in map.
Need For Computerised Village Maps
Cartographers use methods of showing objects on maps in various ways- for example symbols or objects, lines, hatching boundaries etc. Usually separate maps are created for different subjects or themes, thus, giving rise to numerous maps of the same area. Since in most cases these maps are produced by different agencies using no common methodology, the scales of these maps are also quite different. Computerised maps comes very handy for these initial stages of mapping and prove much more useful when mapped data is put to use. Computerised maps allow mapping of details and minor alterations wherever required. The selected superimposition of selected themes gives idea of an integrated picture and helps to understand area by considering variety of features together.
Lacunae in Existing Cadastral Maps
Exhaustive information is available but hardly used. The information collected from the revenue departments is exhaustive but not used at par. This ignores the logical information principle that as far as possible collection of information should be avoided if it is not going to be used. Further, a number of registers need to be unnecessarily maintaining the auxiliary information. Hard print cadastral maps are not easily available for planning process and area away from the reach of common people. Such maps are only the property of government authority and are used as desired by them.
Development in Digital Cartography
The move towards automation has necessitated some redesigning of maps by eliminating some content (Hadley, 1987) and modifications of others like the conventional hatching replaced by coloured filling of specific symbol.
Simplification of information and graphic design are often undertaken simultaneously in manual generalisation, in digital cartography there is a need to distinguish between information generalisation and display generalisation; the former contributes to digital mapping, the latter to visual mapping. Both types of transformations are intellectually demanding and involve a variety of subtasks and processes. Many applications use maps of the same entities compiled at a variety of scales with different content and symbolism. Many land information systems focus on the land parcel and are concerned with the areal extent of such linear objects. A number of users, such as in local government and NGOs, need both detailed and simplified representations of the same objects. At present, scale-related requirements are met by multiple definitions of the same areas. The scale of display appropriate for each feature is also recorded within a scale-integrated database. Systems based on raster/video images zoom by retrieving images captured at the next larger scale. Other researchers are manually integrating road networks captured at different scales for route planning and are investigating database designs for supporting scale-free mapping (Abraham, 1989). The digital mapping has completely transformed cartography since the mid 1980s where map output in fast multiple reproduction made easier.
Methodology
Monitoring is exercised to make a definite assessment of results of actions and activities and there by decide if any change required. Monitoring through digital maps is very effective and useful. By pointing initial and current status on maps the impact area may be easily seen. Creating maps, union, intersection, subtraction and analyses are easily carried out.
Computerization: There is a considerable effort in culling out the information from the registers to prepare reports in the current manual system. The load of processing/calculation is currently placed on lower staff to maintain documents. The objective is to map out land parcel wise basic indicators / vital statistics. It is envisaged that all data would be computerised and presented in a visual form on a digitised map.
After the initial exercise, including necessary amendments to methodology; it is decided to undertake the task for cadastral mapping. The mapping involved the following two processes being undertaken simultaneously:
- Computerised digitization of maps
- Data collection and updation.
Computerised digitization of maps and data is undertaken using cadastral maps basic data like land parcel size, ownership, landuse, cropping pattern and infrastructure details obtained from the “Patwari” as a base. Basic physical features, boundaries and important landmarks were digitized. Other primary baseline and temporal data collected entered in computer system the formulate database.
Cadastral Mapping
Village Khasra (Cadastral) map is very vital and important because it carries the smallest ever mapped land unit in it. The villagers use the maps for general observation at village level and useful for macro level application. Cadastral maps are generally available on 1:6000 or 1:4000 scales. The cadastral maps are consists of all three types of geometries, i.e. point, line and area (polygon). In GIS based cadastral maps all the characteristics like geometry, attribute and map objects are present.
The cadastral maps are generalized form of real earth features on a paper, which involves the application of processes, such as selection, classification, simplification, symbolization and pattern recognition. All cadastral maps are symbolic and rely on the use of a graphic sign language. All the feature, linear and aerial, are demarcated at real scale and area and length of the linear features such as roads and rivers marked by solid double lines can be measures with accuracy due to large scale mapping. While in small scale mapping, such as topographical maps show lengths of linear feature on its scale but areas of most linear features such as roads, railways and single line drainage are as representatives only (Singh, 2005). The design of the symbolization system and of its structure is been based on different parameters. For example, one well within the cadastral map is shown as a small circle, and further qualitative differentiation, based on the lined and unlined well, is also made possible using different patterns of circle.
Cadastral Resource Mapping:
Present important resources available at land parcel level can be considered real perspective for planning purpose. A village resource map gives a useful scenario of the present available facilities & resources, which helps in identification of further required facilities. Therefore, cadastral map used for resource mapping. Figure below shows the characteristics of a digital cadastral map:
Figure-1: Map Characteristics
Cadastral Database
A database is useless unless populated with appropriate data and kept up to date with temporal changes. Digital mapping has a strong capacity to integrate and cover the full range of data sources. The database structure with special reference to Madhya Pradesh cadastral maps can have following records, which are to be constantly updated (Singh, 2005). The record of each map includes information about its:
| Title Information | Records |
|---|---|
|
|
Components of Digital of Cadastral Maps
The digital cartography involves many components to be decided at first hand. Following the major components are used in it:
Map Layers
The layers can be assigned them to different objects in the map to identify different objects easily. Different layers can be assigned different colors and line types. The layers can control the visibility, color and line type of the objects on a layer for editing and analysis. One object can be moved from one layer to another and even one can change the name of a layer. Layers are the different overlays used in paper-based drafting. The layers are the primary organizational tools in the CAD.
Figure-2: Cadastral Layers, colours and line types
The maximum possible number of layers in a cadastral map could be as much as shown in the figure-2. We can assign a name to each layer and select any combination of layers for display.
Symbolization
Symbolization is the science of signs assigned to particular function, with sign considered to be a relationship between an expression and its referent. For cartography, maps can be viewed as tools to communicate meaning primarily through symbols. This implies that there must be a cartographic language based on symbols that provides a map with meaning. Symbolization is most important part of cartography. In the present paper a rich combination of colour, pattern, shape and size of symbols (Figure-3) is provided according to their functions for defining and applying symbolization styles to point, line, or area data. In digital cartography vector and bit mapped symbols are used.
List of symbols
Figure-3: Map Symbols
Apart from the identification of symbolic feature following parameters plays an important role in symbolization process:
- Location
- Size
- Color (Value)
- Texture
- Color (Hue)
- Orientation
- Shape
Digital cartography has significant capabilities for text labeling. Many text font types are now supporting it. Font information can now be embedded in output formats. There are numerous capabilities for storing text in the database as annotations. Annotations are well liked with different font formats so that they can be automatically updated as change happens in the real world. Annotation support now includes such cartographic elements as callouts and leader lines. The fonts provide the cartographer with the freedom to override the strict rules of the font selection.
The stored representation capabilities of geo database facilitate to derive, create, and store cartographic features as layers of points, lines, or polygons. Such cartographic feature classes are often vital to the implementation of digital cartographic models from digital landscape models and can act as a source for subsequent stored representations.
Conclusion
Based on the requirement of different departments and NGOs and approval of authorities extensibility of digital cadastral mapping can be provided to make the Land Records easy to use. Thus, creating a transparent administrative environment. Most State Land Records Departments could use the methodology to make it usual practice.
References
- Abraham, I. M. (1989): “Automated cartographic line generalisation and scale independent databases”, C. N. A. A.
- Bertin, J., 1978, “Theory of communication and theory of the graphic”. International Yearbook of Cartography, 28, 118–26.
- Hadley, C. (1987): “The Ordnance Survey 1:625 000 database map production system, in Robinson”, G. R. (ed.) Going Digital: Pros and Cons, British Cartographic Society Special Publication Number 4, 30 - 49.
- MacEachren, A. (1992): “Visualizing Uncertain Information”. Cartographic Perspectives, N. 13, pp. 10-19.
- Morrison, J. L. (1986): “Cartography: A milestone and its future, in Blakemore”, M. (ed.) op. cit., 1 - 12.
- Peucker, T. K. and Chrisman, N. (1975): “Cartographic data Structures”, Am. Cartographer 2 (1), 55 - 69.
- Singh, R. M. and Trivedi, R.K. (2005): “New trends of digital cartography in cadastral mapping with special reference to remote sensing and GIS applications”, 25th INCA Congress, Indian National Cartographic Association, Dr. H. S. Gour Vishwavidyalaya, Sagar, India, (2005)
- Visvalingam, M. (1989): “Cartography, GIS and maps in perspective”, Cartographic J 26 (1), 26 - 32.