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FAQ's

How to publish links to geographic data and maps?

To publish links to your data on the Sri Lanka GeoPortal, you must be registered and have MOU signed between your department, agency and NSDI office. Then, publish metadata with descriptive information to help users find and evaluate your offerings. Be sure to include yours service URL and registered in Metadata Catalogue.

How to publish a map service?

You can create either provide the data & metadata to the NSDI office to publish the services. You can also create map service implemented using your own Map server. Then, register as a publisher on the Sri Lanka Geo Portal and publish metadata that references your map service.

What kinds of data for GIS are available on the Sri Lanka Geo Portal?

Both free and commercial data sets can be discovered on Sri Lanka Geo Portal including:

  1. Dynamic data and Maps- GIS users can access live data and maps, such as map services, using the Sri Lanka Geo Portal Map Viewer or other GIS software tools.
  2. Downloadable data- Data downloads enable you to perform custom downloads of digital data that you are viewing to access locally with GIS software.
How will the GIS users and others find my content?

Content published through Sri Lanka Geo Portal may be discovered through the Sri Lanka Geo Portal Search, or Data Category pages. Many GIS users regularly develop content that is useful to others. This content may include Data sets, static map images, map files, custom applications, and many more. Publishing your content on Sri Lanka Geo Portal enables you to share your content with the GIS community and beyond.

We encourage you to use the Sri Lanka Geo Portal to share your valuable content with others.

Who publishes on the Sri Lanka Geo Portal?

Content publishers include leading government departments, International communities, Universities and research agencies and data providers in the Sri Lanka.

What is the importance Map Viewer feature has got in Sri Lanka Geo Portal?

You can provide geographic data by publishing map services and images, geographic datasets, geo services, spatial solutions, geographic and land reference material, and geographic activities or events to share with others through submission of on-line provider forms within the Sri Lanka NSDI Portal. Publishing is performed via an online form or an upload utility.

What are the best practices for Catalog/Resource (Datasets/Apps) contribution?

Some of the best practices for contribution are as follows:

  • Data should be stored in widely used file formats that are suitable for machine processing.
  • Released dataset should clearly reflect “what is recorded about a particular subject”.
  • Timely release of datasets is one of the important factors to maximize the utility of information people can obtain.
  • Data should be provided in freely available formats which can be accessed without the need for a software license.
  • Data elements should be in de-normalized form.
What is scale?

Scale refers to measurements on a map, as compared to measurements in the real world. For example, the distance represented by one centimeter on a 1:20,000 scale map would be equivalent to 20,000 centimeters, or 200 meters, on the face of the earth. It is best to think of scale as a fraction in determining whether a particular scale is small or large. For example, data at 1:1,000 or 1:5,000 would be referred to as large scale, while data at 1:100,000 or 1:1,000,000 would be referred to as small scale. In fractional terms, 1:1,000 equals 0.001, while 1:1,000,000 equals 0.000001, and therefore, the 1:1,000 scale data is at a larger scale because the resulting value (0.001 versus 0.000001) is larger. This distinction can be confusing because the amount of area depicted at smaller scales increases, while the amount of detail decreases.

Does scale matter?

In a GIS, data can be physically displayed at any scale desired; however, the compilation scale of the information will often dictate the level or resolution of mapped features that is appropriate. Large scale mapping tends to be more accurate and detailed than small scale mapping. The more detailed the mapping, the greater the effort to collect, store, maintain, manipulate and display the information. Also, displaying very detailed information as a regional level may be slow in a GIS because of the amount of coordinate information involved, and the inappropriate detail may graphically clutter the resulting map view. Conversely, information compiled at a gross scale may not be detailed enough to support local applications.

Based on the above, compiling the geographic information at an appropriate level of resolution involves a careful balance between application needs for accuracy and detail, and the resulting constraints related to building and maintaining the database at that level. On the other hand, display rules can be configured within GIS applications to help users in locating and accessing information depending on the geographic extent of their viewing and purpose of specific applications.

What is relationship between accuracy and scale?

The relative accuracy of linear and aerial measurements may vary from one place to another but on the other hand, accuracy requirements become less stringent as we move up to smaller scales. Therefore, maintaining a comprehensive metadata on the various data sources with their accuracy levels is very crucial. Also, when linear features such as roads and highways are compiled at a relatively large scale, it is recommended that a generalized version of those features be derived when they are displayed at smaller scale in order to reduce GIS application performance degradation. However, when facility data has been compiled as point features at a given scale, they can be re-projected at the smaller scale “on-the-fly” by the application software without excessive performance degradation.

What scales are relevant for the SL NSDI?

All scales are relevant for the SL NSDI. However, for the purpose of organizing this foundation stage, scales will be grouped in the FGDS in three levels or ranges:

Large. The mapping scale for this level is 1:1,000 – 1:5,000+. This scale is required primarily for engineering level works including facility mapping and management, streetscape design, urban and architectural design and localized environmental inventory and assessment. This scale is suitable for all aspects of engineering planning and design, but does not preclude the need for site specific engineering work, including site surveys and the locating of underground utilities, before actual implementation.

Medium. The mapping scale for this level is 1:10,000 – 1:50,000+. This scale mapping includes urban and peri-urban areas. Data compilation for this scale may be carried out at 1:1,000 and generalized to this level. This level of data is often used for urban land use planning, transportation planning and analysis and boundary delineation.

Small. The mapping scale for this level is 1:100,000 and above. This scale mapping includes the urban hinterland, rural areas and other areas of distributed human settlement, farms, plantations and related issues, and usually depicts relatively generalized information for the entire emirate. Such mapping may be carried out using data compiled at 1:10,000 to 1:25,000 and generalized to this level. This level of data is often used for land use planning, natural resource inventory and assessment, toxic release modeling, localized groundwater modeling, soils and superficial geology mapping, and for assessing such issues as climate, emirate-wide groundwater assessment, and urban growth projections.

How can one view the Metadata content?

You can use the metadata detail and the full metadata view to browse through information to locate what you are looking for. Map data can be viewed in the Map Viewer or with GIS software to display multiple data sources from the Sri Lanka Geo Portal along with data from local sources.

What is Metadata?

Data about the data is called metadata. Information about the datasets being published through a standard structure comprising of controlled vocabularies on government sectors, dataset types, jurisdictions, access mode, etc. Apart from facilitating easy access to data, it is useful for federation & integration of data catalogs.

What kind of content can we publish?

There are two types of contents to publish to the Sri Lanka Geo Portal: Publish metadata that reference map services or Internet mapping systems that users can view online and/or download. Publish metadata that references geographic data, maps, resources, or activities that users can access information about and/or download from the internet.

What is the role of Data Contributor?

In order to cater to the contribution of the datasets from offices/organization under the Ministries/ Departments, the SL NSDI office nominates a number of Data Contributors who would be responsible in contributing the datasets along with their metadata.
Data Contributor could be an officer of the Ministry/Department who would be responsible for his/her unit/division.

The responsibilities of the Data Contributor are as follows:

  • Responsible for ensuring quality and correctness datasets of his/her unit/division.
  • Preparing and contributing the metadata in the predefined format for the datasets.
What are the classifications of data?

Different types of datasets generated both in geospatial and non-spatial form by Ministries/Departments shall be classified as shareable data and non-shareable data.
The derived statistics like national accounts statistics, indicators like price index, databases from census and surveys are the types of data produced by a statistical mechanism. However, the geospatial data consists primarily of satellite data, maps, etc. In such a mechanism, it becomes important to maintain standards in respect of metadata, data layout and data access policy.

 

What kinds of documents are available?

Several types of documents are available on Sri Lanka Geo Portal including:

  1. Map Files: Map files are digital maps that can be viewed in a mapping application. Map files are typically completed maps that are ready for viewing, publishing and printing.
  2. Static Maps: You cannot directly interact with static map images as you can with dynamic data and maps. You can view them and download them to your computer.
  3. Other Documents: This category includes geographic information stored in the text files, spreadsheets, or other formats and can be used in conjunction with geographic data. In many cases, they can be viewed and downloaded.
What are the formats in which datasets should be published?

SL NSDI recommends that datasets has to be published in an open format. It should be machine readable. Considering the current analysis of data formats prevalent in Government, it is proposed that data should be published in any of the following formats:

  • CSV (Comma separated values)
  • XLS (Spread sheet - Excel)
  • ODS/OTS (Open Document Formats for Spreadsheets)
  • XML (Extensive Markup Language)
  • RDF (Resources Description Framework)
  • KML (Keyhole Markup Language used for Maps)
  • GML (Geography Markup Language)
  • RSS/ATOM (Fast changing data e.g. hourly/daily)

 

What kinds of data are available?

There are a variety of data types available to discover and use on Sri Lanka Geo Portal. These include:

  1. Dynamic Data and Maps. GIS users can access live data and maps through Web Map Service (WMS), using software tools viz. Sri Lanka Geo Portal Map Viewer.
  2. Downloadable Data - Data downloads enable you to perform custom downloads of digital data you are viewing to access locally with GIS Software. Visit the Free Viewers page for a list of GIS data viewers.
  3. Offline Data - Many publishers offer data that can be ordered online.
What type of content can be found in Sri Lanka Geo Portal?

There are three categories of geographic content available on Sri Lanka Geo Portal: data, documents and resources. Each category has a number of content types. Search for data if you want to download, order or add data or map services directly to your map. Search for documents if you are interested in map files, static map images and geographic information. Search for resources if you are seeking links to external Web sites, data clearing houses, Geographic Information System (GIS) based Web Applications and geographic activities.

What are Fundamental Geographic Data Sets (FGDS)?

The FGDS framework is a set of essential data themes which are the building blocks for planning and design of a national spatial data infrastructure. There already exist international data model standards that address many of the fundamental data topics that will be developed through large or emirate-wide projects. Because these models reflect the experiences and results of trial-and-error to many considerations by a broad group of users, they are often quite comprehensive, large and complicated. The SL NSDI Team reviewed many of these models for their applicability to the situation in Sri Lanka and crafted an overall Data Framework to meet the needs of the broader SL NSDI, inclusive of ongoing and planned emirate-wide projects. A data framework and model research report was generated previously that presents the results of this research and developed an FGDS framework for Sri Lanka. It is expected that this initial framework will be periodically updated and refined as the SL NSDI development progresses.

What is the Sri Lanka National Spatial Data Infrastructure (SL NSDI)?

The Sri Lanka National Spatial Data Infrastructure (SL NSDI) is conceived as a national programme to harmonize, integrate and optimize the development and sharing of fundamental geographical and statistical information across all government agencies and institutions. The development of this programme is being carried out through a step-by-step, practical process that will establish a strategic and evolving framework for a long term SL NSDI, and provide coordination and support to the development of its various components through a carefully conceived and guided incremental process. It is recognized that this infrastructure can only be as strong as the community of agency stakeholders that comprise it, thus each component of the programme will seek to build on and leverage the many good works being carried out in many of the more progressive agencies in Sri Lanka, across all sectors. This programme is being sponsored in Sri Lanka by the Sri Lanka National Spatial Data Infrastructure (SL NSDI) and implemented by Information and Communication Technology Agency of Sri Lanka.

What is Spatial Data Infrastructure (SDI)?

A Spatial Data Infrastructure (SDI) provides a framework of standards, policies, data, procedures, and technology to support the effective coordination and sharing of spatial information among a community of stakeholders. Extensive national SDI programmes are now underway in North America, Europe, Australia and elsewhere, and a Global Spatial Data Infrastructure (GSDI) programme has been formed. These existing programmes have established important groundwork, but some countries with rapidly transforming economies are not organizationally ready to adopt these models at a similar rate of development, and many have special political, economic and legal contexts that require a unique approach. For most countries in the world, SDI involves a step-by-step, incremental process that must acknowledge the special circumstances of each nation.

What is NSDI?

National Spatial Data Infrastructure (NSDI) defined as the technologies, policies and people necessary to promote sharing of geospatial data throughout all levels of government.

How to become a member of SL NSDI?
  1.  Open your browser (Google Chrome, Mozilla Firefox, Internet Explorer, Safari or any web browser)
  2. Start typing www.slnsdi.com
  3. On the home page you find New User/Login
  4. Click on New User, and create your own credentials for logging into the application.
What is WGS?

The World Geodetic System (WGS) is a standard for use in cartography, geodesy, and navigation including GPS. It comprises a standard coordinate system for the Earth, a standard spheroidal reference surface (the datum or reference ellipsoid) for raw altitude data, and a gravitational equipotential surface (the geoid) that defines the nominal sea level.

WGS 84 is the reference coordinate system used by the Global Positioning System (GPS).

How to be a user of NSDI Portal?

Please follow the above process for registering the user. Once the user is registered, based upon his/her access privilege, the user can access the application.