Adopting Geo-ICT in Survey Department

Adopting Geo-ICT in Survey Department:

Need for Capacity Building

Kalyan Gopal Shrestha

Deputy Director General

Survey Department

e-mail: kalyanshrestha@gmail.com

Abstract

The Geospatial Information and Communication Technology (Geo-ICT), is gaining momentum and has revolutionized the Surveying and Mapping profession. Since the geo-technology is evolving continuously, constant efforts are being made for its diverse applications. Most of the users are convinced that digital technology is known for its easy use and the power to improve their work process. Survey Department has witnessed tremendous changes in the technologies and corresponding policies in Global scenario in last fifty two years of its history and particularly during last two decades. Adoption of Geo-ICT has become indispensable in the present context. Even though Survey Department, so far, is not in the stage of fully exploiting the Geo-ICT, Time has come to think of adopting Geo-ICT application. Because, the wider use of Geo-ICT could be prime instrumental to support the overall Surveying and Mapping business. The success of efficient Geo-ICT application heavily depends on the capacity building, institutional reforms, devolution, education and continuous training, and ultimately the commitment of the government.

This article has tried to focus on various factors responsible for successful implementation of Geo-ICT in Nepalese context.

Introduction of Geo-ICT

Geo-ICT means Geospatial Information and Communication Technology. The concept of Geo-ICT is to integrate the Geospatial technology into the mainstream of Information and Communication Technology (ICT). ICT and Geo-ICT are rapidly gaining momentum as an

indispensable research methodology in geography, environmental science etc.

Geo-Information and Communication Technology (Geo-ICT) includes convergence of various modern technologies dealing with various aspects of spatial data management including: data acquisition, data assimilation, data analysis, information generation, decision support, and information dissemination. Geographic Information System (GIS), remote sensing, Global Positioning System (GPS), satellite communication system and web technologies are the chief technologies falling under Geo-ICT.

There are many Geo-ICT applications. GIS could be considered as part of Geo-ICT. Geo-ICT provides even broader applications that traditional GIS may have not addressed well. Geo-ICT is truly an interdisciplinary area that would require the integration of GIS, GPS (position tracking), RS (remote sensing), satellite wireless communication systems, mapping technologies etc.. More importantly, the wise use of Geo-ICT could be prime instrument to support the overall objective of the Land Administration System (LAS) of the nation.

Geo-spatial revolution led to acquire and update knowledge towards high end research resulting Geo-ICT (Geo-information and Communication Technology). The role of Geo-ICT has become vital for local level geo-spatial planning. Spatial data management includes: data acquisition, data assimilation, data analysis, information extraction, decisions support and data/ information dissemination.

Necessity for adopting Geo-ICT

The twenty-first centuries is the age of ICT and numbers of technologies are evolving day by day to accelerate the efforts for the maximum yields. Among the many applications of the information technology, Spatial Information System holds the potentiality of rendering significant contribution on policy-making, formulation of plans, infrastructure development, natural resource management and other development activities. Geo-ICT will have a significant impact on geomatics sector, industry, research and academia. This emerging technology will open up many new applications resulting from a great improvement of data flow efficiency, on-line data processing, management and calculable savings of operational costs.

Now-a-days, most of the professionals have moved from conventional analogue to digital. Since the geo-technology is evolving continuously, constant efforts are made in its diverse applications. This acceptance comes from a growing understanding about the technology and its benefits. Most of the users are convinced that digital technology is known for its easy use and the power to improve their work process.

The technologies in the information and communication discipline are developing rapidly. Information and communication technology (ICT), more specifically Geo-ICT, has provided the opportunity for improving quality and cost effectiveness in the production and dissemination of geo-information products.

Even though the traditional disciplines are very essential for infrastructure development, the specialized and modern areas are more important for comfort, safety, accuracy and reliability.

Adoption of Geo-ICT in Survey Department

In over 50 years of history, Survey Department has witnessed its growth from cadastral surveying unit to National Mapping Agency with the hub of National Geographic Information Infrastructure in Nepal. It has traveled from Chain and Compass survey to Satellite technology.

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The technologies and corresponding policies have undergone tremendous change or development in last fifty years and particularly during last two decades. Speedy development of technology in the field of surveying and mapping demands the changed role of surveyors and surveying institutions.

Survey Department is responsible for cadastral survey and preparing land records or establishing Cadastre. Cadastral survey is the source of key information for the comprehensive Land Information System. An efficient Land Administration can not be imagined without accurate and reliable cadastral information.

Survey Department is gradually and slowly replacing the traditional methods adopting modern methods but yet much remain to be done. Survey Department, so far, is not in the stage of fully exploiting the Geo-ICT

In this context, it has already introduced some of the systems such as establishment of Geodetic Network and densification of control network by Global Positioning System Survey, Topographical base maps updating using Remote Sensing technology and Nepal-India border strip mapping by Geographical Information System technique and Digital technology for cadastral mapping. .

The advancement of Geo-ICT technology has been so rapid that it is very difficult to adopt in our organization by virtue of lack of resources (Human, finance and others). Majority of the Human resources are turning out of date with the speed of change.

In many developing countries there is a lack of university education in Geomatics. Indeed low levels of technology, less skilled staff and lethargic processes are the critical issues in geospatial field. Appropriate ICT investment and capacity building are necessary conditions for establishing accurate geodata management for sustainable development. Education, training and research on geoinformation science are the fundamental factors for sustainable Geo-ICT use.

Land Administration is strongly influenced by social, cultural and bureaucratic environment, and overlooking of the existing practices and capacity would make failure in adopting such new technology. In this context, Geo-ICT has the vital role to play and has to be looked upon the overall objective

Although the cadastre system was focused to fiscal purpose in the beginning, it is being gradually used as legal and multipurpose cadastre. Updating of the cadastral maps is undertaken by district survey offices of Survey Department. Computerization of existing land records and cadastral maps to develop land information system and provide computer-based land administration services is under progress.

Progress so far achieved in adopting Geo-ICT

GPS survey for establishing geodetic controls was initiated by Survey Department in 1992. This survey is continuing to provide necessary control points to support cadastral surveying in different districts of the country.

Survey Department produced a new series of Topographic Base Maps between 1992 to 2001 at the scale of 1:25,000 (for the terai and middle mountains) and the scale of 1:50,000 (for the higher mountains and Himalayas) covering entire country in paper print. And subsequently converted all those maps into digital form by GIS technology and made available to the users as National Topographical Database (NTDB). Survey Department is working to create digital data files at smaller scales as well. Data files at a scale of 1: 100,000 are already available and has a plan to produce in 1:250,000, 1:500,000 and 1:1000,000.

With the mission of strengthening and developing geographic information infrastructure for the access of geographic and related data for decision-making, National Geographic Information Infrastructure Project (NGIIP) was established under Survey Department in 2002. This project facilitates the sharing of Geographical information among Geographical information user organizations within the country. This project has published Socio-economic atlas of Nepal and made available in CD-ROM, hard copy and on the web.

Topographical base maps, which were prepared during 1990’s are updating with Remote Sensing Technology. Survey Department has also prepared Global map of Nepal, Ortho-photomaps of Urban areas, CD of Soil and Terrain Data of Nepal SOTER NEPAL Version: 1 and has developed an Operational Metadata system through NGIIP.

Survey Department proposed Cadastral Logical Framework Plan in Fiscal Year 2005/2006 with a vision of replacing traditional technology with digital technology in ten years time. In this line Cadastral Survey Branch under Survey Department started re-cadastral mapping by Digital technology and development of Land related information system from 2006 in Ward no. 6 of Banepa Municipality of Kavre District as a piloting project. After evaluating the success of piloting job, survey was extended to the rest of the wards too. Survey works have been finished so far in 9 out of 11 wards of the Municipality. Surveys in rest of the two wards are continuing. Survey Department has proposed a plan of extending this kind of job in Dhulikhel Municipality for the coming fiscal year.

Significant numbers of Geo-referenced cadastral map sheets from various district survey offices have been digitized by Department of Land Information and Archive. Survey Department can use these data if needed.

Himalayan Airborne Gravity survey is under way to facilitate the National Geoid determination.

Capacity building for efficient Geo-ICT application

The present pace of progress in Digital Cadastral and Topographical Map updating seems far lag behind to meet the real sense of cadastral mapping and topographical map updating. Survey Department is thinking of initiating cadastral survey through Ortho-photo based technology for Achham and Arghakhanchi districts, where old cadastral records were completely destroyed during conflict.

Our present capacity may not be sufficiently supportive to bring about the desired result with the situation at hand. The accomplishment of above mentioned jobs can be materialized only when we strengthen our current capability. Immediate plan of action for Capacity building is thus an essential aspect to be addressed upon before adopting Geo-ICT for that purpose. Geo-ICT offers an opportunity to build land administration enhanced and efficient. But in a developing country like Nepal, where traditional methods or processes are still in practice, full fledged Geo-ICT application is still a far cry.

The success of efficient Geo-ICT application heavily depends on the capacity building, institutional reforms, devolution or location based services, education and continuous training, and ultimately the commitment of the government.

Effective utilization of any technology depends mainly on the qualified and well trained manpower. So, effective education and training programs are to be imparted. Attempts are on in this direction. Kathmandu University and Land Management Training Center have collaboratively commenced academic under-graduate course of B.E. in Geomatics Engineering since August 2007. Till date three batches have been enrolled. This program includes Geo-ICT based land administration education. Versatile and qualified manpower’s team can be expected from academic course of B.E. in Geomatics Engineering.

Land Management Training Centre (LMTC) has a proposal to transform its one year Basic and Junior courses into a three-year Diploma in Geomatics Engineering course, and to offer a two-year post-graduate degree programme.

However, since most of Survey officers have obtained further Post Graduate and Masters level studies abroad in various survey faculties including geo-informatics and use of ICT. Thus they can make use of ICT for their respective works.

The continuous support of ITC in providing scholarships to various level courses ranging from Diploma to Masters Level and the support from JAXA for capacity building of Survey Department by conducting mini-projects for disaster management have contributed the department. Coordination and cooperation among the organizations involved in space technology application and enhancing awareness in its importance could boost up the effectiveness. Furthermore, regional cooperation in this sector including human resource development, a proper platform for data sharing, etc. is equally essential for maximizing space benefits

Sporadic transfer of staff from other branches or sections to particular specific branches/sections without previous experience and skill of related works has hindered the working flow. Proposed functions of the individual are to be assessed on the basis of past education, experience and skill possessed by individual before transfer. Otherwise, remedial training must be imparted immediately after transferring such kind of personnel.

Constraints

In present context, Survey Department has following constraints for adopting an efficient adoption of Geo-ICT :-

§ Lack of awareness among political leaders and policy planners resulting low priority in this discipline. There is little recognition that ICT can be used to supplement and complement the conventional system or processes,

• Lack of proper and sufficient education in this field, proper human resources and expertise.
• Lack of Infrastructure: Some of the problems include lack of reliable electricity supply, lack of bandwidth capacity in internet.
• Lack of financial support for managing Hardware, Software and Humanware.
• Related technology changes very fast and is difficult to keep pace with such changes.
• Replacement of traditional equipments and methodologies by digital technology has tremendously demanded increased and enhanced knowledge and skill.
• The original cadastral plans of half of the districts of Nepal were based on local survey control. They are described as so-called island maps and those map sheets are in hardcopy format. The “island maps” are not geo-referenced and hence cannot be digitized directly into the geo-spatial database.

Issues to be addressed

Adopting Geo-ICT remains a complex problem in Survey Department and the implementation of Geo-ICT is certainly a challenging task ahead in the present context. A firm commitment on the part of Policy planners, high level managers and whole hearted support from all the staffs may be the starting point.

The following Prime issues were identified for successful implementation of Geo-ICT:-

§ Technical issues, which include system components, system design, and technical expertise;

§ Organizational issues, which include how well the staff of an organization understands the technology and its role, and how the organization adapts to new sources and types of information;

§ Project management and process re-engineering related issues; and

§ Institutional issues, which include factors external to an agency that influence an organization's ability to adopt or use Geo-ICT.

Plan of Actions

The efforts should be concentrated for the following plan of actions to adopt Geo-ICT effectively and efficiently:-

1. All the issues namely technical, organizational, project management, and institutional are important for geo-information management in the country. These issues are to be addressed while making plan of actions.

• Development of human resource is a pre-requisite; a continuous system of education, training and technology transfer need to be planned in house or abroad.
• Job placement and transfer should be wisely administered.
• Hardware and software:

o adding Geo-ICT aids,

o its maintenance and updating

• Enactment of Survey Council Act.
• Policy for the Geo-ICT to be adopted to ensure effective and efficient utilization of resources.
• A strategy for formulating measures to control brain-drain.
• Organizational re-structuring suited to Geo-ICT need to be carefully planned.
• Resistance and/or non-cooperation from the existing staff in adopting new technology need to be addressed effectively
• A strategy for the transformation from manual to Geo-ICT (re-engineering) has to be carefully planned and adopted
• Participation of the public and private parties: and winning their faith in the new system is a pre-requisite: However, there are very few private parties, which can contribute to the implementation in Nepal.

2. Geo-ICT applications at present have poor implementation scenario. Hence a strong need for research is felt in the area of geo-information management in the country.

3. Constitute a task force on ‘geo-information management’ by inducting professionals having expertise in technical, organizational, project management, and institutional areas.

4. The task force should also be assigned to bring out a business model for Geo-ICT products at Private partnership for its greater sharing between various stakeholders.

Private participation in Geo-ICT

All necessary conditions for the successful adoption of Geo-ICT cannot be imagined to be materialized only through the governmental efforts. In the new political environment of Federal Democratic Republic of Nepal with open policy of Privatization, there may not be any more monopoly of government in mapping and geo-information sector.

Land (Survey and Measurement) Act revised in 1999 has made a provision of licensing to qualified surveyors, twenty seven surveyors have already got licenses, but have not fully implemented yet due to lack of supportive regulations and few other bureaucratic reasons. It can be expected that the system will start soon. Till date licensing surveyor’s participation in Geo-ICT application has not been surfaced.

There are four professional associations namely Nepal Surveyor Society, Nepal Surveyor's Association, Nepal Remote Sensing and Photogrammetric Society and the Nepal Association of Chartered Surveyors to promote the Geoinformatics profession. However, their activities in the professional development and contribution to the Geo-ICT technological development in their respective fields lag far behind. Their activities are found limited to arranging a few number of seminars and publication of journals.

Survey Department should take a pivotal role in the country through Public-Private Partnership and Public-Public Partnership by bringing in the professional’s associations and private licensed Surveyors in Geo-ICT activities for land management.

Conclusions

In spite of numerous constraints, the importance of Geo-ICT applications can not be neglected to keep pace with the advancement of technology and to serve the overall development of the country. Due to various reasons mentioned above the Department has not been in position to adopt Geo-ICT to desired potential. So, national and international cooperation in this respect might be the possible solution to address the capacity building of the department. However, Government policy makers continued support and the participation of the stakeholders are also equally vital for its sustainability.

The wise use of Geo-ICT could be prime instrument to support the overall Geomatics business. The success heavily depends on the capacity building, institutional reforms, devolution of functions and services, education and continuous training, and ultimately the full commitment of the government and other stake holders.

References

1. R.R.Chhatkuli,2002,NationalGeographic Information Infrastructure, Programme to support NGIS in Nepal, Nepalese Journal on Geoinformatics, Vol 1
2. Maheshwar Bhattarai, 2005, Land Resource Management and Human Resource in context of space technology application in Nepal, A seminar paper
3. Rabin Kaji Sharma and Toya Nath Baral, 2005, Survey Department in the General Context of Land Mnagement, Proceedings of the colloquium on the role and functions of Survey Department in the context of broader technological development
4. Ganesh Prasad Bhatta, 2006, Applications of open source software in Land Administration, Nepalese Journal on Geoinformatics, Vol 8
5. Sjaak Beerens, 2006, Building Capacity in Geoinformation Handlings, Archives of Remote Sensing and Spatial Information Science, Vol. XXXVI
6. Babu Ram Acharya, 2009, Adopting Geo-ICT application for Land Administration, 7^th FIG Regional Conference paper
7. Pramod K. Ssingh, 2008, Of opportunities and challenges, GIS Development, 2008August issue.

Parcel Mapping Using GIS

parcel mapping using GIS

Kalyan Gopal Shrestha[1]

1.0 Introduction

The concept of parcel mapping goes as far back as ancient China, Egypt and Babylonia. With the increase in global population and mostly due to increasing property values and rapid development, towns began to realize the importance of having accurate parcel maps. Literary meaning of a Parcel is an area of land, usually with unique owner/tenant, land class and use, and bounded by wall, fence, bond or boundary markers.

The utility of a parcel map is that it allows for easy identification of where a property is located relative to public ways and adjacent properties. An adequate parcel map should reflect size and shape of each individual parcel owned in a town.

1.1 Parcel mapping in Nepal

Although the present cadastral database is adequate for the day to day functioning of administration of land, the Survey Department targeted to initiate Numerical cadastre method to be used for mapping for greater accuracy, to prepare parcel based Cadastral Information System with a priority to regions of high population density for Land Information System and Preparation of Parcel Plan of land, and provide the data to the respective landowners.

Recently, a concept has been developed to prepare a parcel plan individually and also to carryout the survey using Total Station Theodolites in order to reduce the number of disputes, to increase the accuracy of mapping and to support the establishment of parcel based cadastral information system.

1.2 Digital parcel

Development of computer technologies along with geographic information systems (GIS) created opportunities to conduct this work more efficiently. It is much easier to store, maintain and update a digital map than an analog paper map. Digital parcel mapping also simplifies the process of locating the information about any of the parcels and markedly reduces time necessary for making changes and printing new copies of the maps on paper. Digital parcel maps can be integrated into a more general geographic information system that will allow users to maintain and retrieve the record of zoning, land use, conservation easements, etc.

2.0. Parcel Mapping Methods

One of the important steps in creating digital parcel maps is conversion of traditional paper maps (or analog maps) into digital GIS data layers. Not only do the data have to be transferred into a digital form, but they also have to be vectorized so that GIS software would be able to distinguish between individual elements such as lines, points, and polygons. There are several ways to do this:

- Manual digitizing from analog maps;

- Scanning with further “heads-up” digitizing or automatic vectorization;

- Coordinate Geometry conversion (COGO);

- Positioning property corners with GPS.

2.1. Manual Digitizing from Analog Maps.

This is the most basic method of digitizing traditional paper maps. Manual digitizing is done by placing a paper map on a digitizing board and entering all the elements of the map into the data base by means of a sensitive digitizing puck. An operator enters data by placing the digitizing puck over the points on the map attached to the digitizing board and pressing different buttons on the puck, thus indicating the type of each point. A point can be either an individual element, or a part of a larger element such as a line or a polygon. Lines and polygons are still defined by a set of points entered by an operator and connected by lines (vectors). Therefore, the accuracy of the data depends of the accuracy of the location of the points.

Digitizers are capable of providing a very high degree of accuracy in defining the location of each point (as high as 0.002” to 0.005”). Still, the accuracy of the data depends to a great extent on the accuracy and skills of the operator who manually enters the points by means of the digitizer. Usually, after all the data have been entered, it is necessary to edit them in order to get rid of operator’s mistakes.

Accuracy of the digital data also depends on the accuracy of the analog map. If lines on an analog map are misplaced, the operator will be able to correct them only to a certain degree. It means that most of the analog map inaccuracies will be very accurately reproduced on a digital map.

Manual digitizing has its own advantages and disadvantages as follows.

Advantages:

· The ability to correct errors or distortions in the original maps at the time of data capture.

· Highly reliable human recognition of map objects.

· The ability to interpret ambiguous or incomplete information and select the relevant required information at the time of data capture.

Disadvantages:

· The process is labor intensive and therefore very time-consuming and costly.

· The quality of results is highly dependent on the operator experience.

· The results may be inconsistent due to varying operator conditions, stress, and fatigue.

2.2. Scanning

The second method of parcel data conversion is scanning. In order to be scannable, a parcel map should be in a very good condition with minimum text on it. Hardcopy parcel maps are converted to digital form using a scanner.

Raster format is not very useful for many GIS applications. A raster image is simply a picture and can not be manipulated by the user. In order to be able to edit or update the map it is necessary to convert the raster image into a vector one. There are two methods that could be used for this purpose: automatic vectorization and heads-up digitizing.

2.2.1. Automatic Vectorization

This method could be used only if a map is in a very good condition – all lines are clear, have similar thickness, and clear intersections, and if there is no annotation or unnecessary features on the map. If this is the case, then the software can trace all the lines on the map and it would leave little editing to perform afterwards. This is the easiest and quickest method of parcel data conversion, but, unfortunately, parcel maps are usually not in perfect condition and have all types of different features and text on them. Vectorization software can not identify features (for example, it can not distinguish a water body from a parcel line), and most types of vectorization software can not distinguish text from lines. If a map cluttered by many different features is vectorized, it will require a lot of editing afterwards to delete all extra features and annotation. Time spent editing such a map could easily overweigh time spent on map conversion done by some other method. To minimize editing required after vectorization, it could be necessary to manually redraw a parcel map on Mylar selecting only parcel lines and thus excluding all extra features and annotation.

This method has certain advantages and disadvantages.

Advantages:

· Could be very fast and cost effective

· Relatively inexpensive

· Provides a very accurate representation of the analog map

· Easy

Disadvantages:

· False recognition of different features and text

· Editing could be very labor intensive

· The analog map needs to be in a pristine condition with minimum extra features and annotation

2.2.2. Heads-up Digitizing

This method is usually used when the analog map is in a very bad condition and when the digitizing board is not available. Heads-up digitizing involves manually tracing the lines on a computer screen over the top of the scanned raster image. The raster image is used as a background image. Everything that was said about on board digitizing could be applied to on screen digitizing as well. There are several advantages of this method

over on board digitizing:

1. Several people can do on-screen digitizing simultaneously because this work could be distributed between several computers, whereas it is very seldom that an organization would have several digitizing tables;

2. Heads-up digitizing is not as tiring as a board digitizing because an operator remains in a seated position, whereas on-board digitizing requires an operator to be in a standing position all the time.

2.3. Coordinate Geometry (COGO)

This is a more accurate method of parcel data conversion to a digital form than any of the methods mentioned above. COGO uses a completely different approach to the process of data conversion compared to digitizing or scanning. The difference is that the analog map is not involved, but land surveys and deeds are used instead. Land surveyors’ record information about each individual parcel in terms of geometric distances and angles from control points (benchmarks). The COGO procedure involves entering into computer such information as a precise starting coordinate, the direction and distances of each side of the parcel. After that, the computer performs some calculations to create a geometrically accurate parcel polygon. Unfortunately, not all parcels have property boundary descriptions or the information could be wrong. Therefore, it is often necessary to go out in the field and collect the missing information or verify the existing documentation.

COGO also has its own pluses and minuses.

Advantages:

· Provides an excellent positional and dimensional accuracy

· Provides a check on the closure (should start and end at the same point) and surveyed area of each parcel

· It is not necessary to have a hardcopy parcel map

Disadvantages:

· The most time consuming method

· Very labor intensive

· Very costly

· Deeds for all parcel must be accessible

2.4. Positioning Property Corners with GPS

The property corners of many surveyed and platted parcels are usually marked with iron pipes or nails. If coordinates of these markers are somehow obtained and input into GIS software, it would only be necessary to connect the dots in order to get a very accurate parcel map. The resulting accuracy could surpass even that of COGO (Struck 1998, np). Today, with the rapid development of the Global Positioning System (GPS)*, it has become relatively easy to get coordinates for the property corners. In order to obtain coordinates, two different strategies could be used: static positioning or kinematic positioning.

Advantages and disadvantages of this method are summarized in the table below.

Advantages:

· Provides the best accuracy

· Analog map is not required

· No guesswork

· All questions are resolved in the field, not in the office

Disadvantages:

· Obstacles can block or reflect satellite signals

· Very labor intensive

· Time consuming

· Requires training

2.6. Example of Analog and Digital Parcel Maps

Figure 2.6 illustrates scanned analog map. Apart from parcel lines, it also shows parcel numbers, acreage, parcels dimensions, street names, and other features. Figure 2.7 shows the same parcel map, transferred into digital form by means of digitizing. This map shows only parcel lines. All other parcels characteristics could be added to the attribute table associated with the map and optionally shown on the map.

Figure 2.7 Digital Parcel Map Figure 2.6 Analog Parcel Map

2.8 Selection of the Best Conversion Method

The choice of the particular method of parcel data conversion depends on the availability and quality of the source maps, availability of the specialized software, and the requirements for quality and completeness of the data vs. the cost of the project. Before initiating the process of conversion, one must evaluate the availability and quality of existing maps. Some of the questions that have to be asked are:

1. Were the maps originally drafted from deeds, surveys, and subdivision plats?

2. Do the original land base and parcel maps meet the GIS accuracy requirements

3. Have the maps been maintained on a regular basis?

4. Do the current maps visually edge match?

5. Are the current maps drafted at an acceptable scale?

If the answer to any of these questions is “no”, it might be necessary to recompile the paper maps before starting the process of conversion or use a method that does not require the analog map.

3.0. Georeferencing

A crucial element of any parcel mapping project is registering a parcel map with the correct real world coordinates. This procedure is called georeferencing. If the parcel maps are not georeferenced, no other information can be displayed over or positioned under the parcel map coverage. Georeferencing could be done either before or after the process of parcel data conversion. There are two groups of methods that could be used for this purpose depending on source materials available in each particular case:

1) Registration to a coordinate system; and

2) Registration to a base map

3.1. Registration to a Coordinate System

3.1.1. Use of Existing Coordinates

The first method of digital parcel map registration is to use the known coordinates. Currently, most of the towns in Nepal have their parcel maps in the form of large blueprints that were originally hand drafted.

Some of the towns may even have coordinates displayed in the corners of individual parcel maps. To use the known coordinates is the easiest way to register the map. If the known coordinates are used, maps become precise.

3.1.2. Use of Artificial Coordinate System

Unfortunately, not all towns possess maps registered to a known coordinate system. In such cases, artificial coordinate systems are frequently used. One way to create such a coordinate system is to assign the lowest corner a (0,0) coordinate and then calculate coordinates for all other corners of each parcel map on the basis of the distance from the original (0,0) point.

A parcel map created by this method will not be registered to any real world coordinate system but the distance between any parcels on the map will be accurate relative to each other. Afterwards it will be possible to register this map to some existing coordinate system or to a base map.

3.1.3. Use of GPS Technology

Another way to create the coordinate system for the town is to use Global Positioning System (GPS) technology. GPS receivers differ among each other depending on the accuracy they produce and their cost. It is possible to distinguish three types of GPS devices depending on their use:

1. The most basic “handheld GPS receiver”– Provides accuracy of several 30 m.

2. Professional, “mapping” grade receivers. Provide accuracy of several metre.

3. “Survey grade” or Phase based receivers. Provide accuracy of several metres.

There are several factors that can affect accuracy of the GPS readings:

• Equipment error.
• View of the sky may be obstructed by trees and other objects.
• Signals may bounce off the buildings, mountains, etc.
• The Department of Defense may turn on “selective availability”, which is an intentional clock error introduced into the timing signals.

One of the GPS applications is parcel mapping. GPS may be used to determine coordinates of easily identifiable positions on a parcel map (such as road intersection, property corner, etc.). In order to register a parcel map to real world coordinates it is necessary to have at least four coordinates. But in order to achieve greater accuracy usually it is better to have more than four coordinates. Another issue is the placement of the coordinates – if all four or more coordinates are concentrated in one corner of the map, it will be possible to register the map, but all other corners will be skewed and accuracy of the map will be very low. The choice of the number of coordinates in each case depends on the shape and complexity of each particular parcel map. In general, however, the more coordinates are used, the more accurate the final map will be. There are certain benefits of this method of parcel maps registration:

1. It is inexpensive

2. It is easy to use

3. It is not time consuming relative to other methods

4. It is not labor intensive

5. It is accurate

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[1] Chief Survey Officer, Topographical Survey Branch

Integrating Survey and GIS

Integrating Survey and GIS

The 2007 summit will be enhanced to include prevalent issues in engineering along with new land development and construction, highlighting experts who are merging geospatial technologies in their work. The program is designed to share knowledge in a GIS framework for

• Business of Surveying
• Construction/As-Built Surveying
• Engineering and Engineering Design
• Geodetic Control
• GPS Technology
• Integrating Survey Data and GIS
• Land Management
• Lidar/Photogrammetry
• Survey GIS Educators

Survey & Engineering GIS EXPO
Conference sponsors and vendors with solutions for survey and engineering will be available to answer questions and demonstrate applications during the Survey & Engineering GIS EXPO and reception. This special event will enable attendees to network with industry colleagues and experts from a wide range of organizations. During the reception, food and drinks will be provided along with live music. Raffle opportunities will be provided by summit sponsors.