LandScan Frequently Asked Questions

  1. What is the input data and methodology that supports the development of the LandScan data?
  2. WARNING:Why are my national level population counts calculated significantly lower/higher than the published country numbers? 
  3. What software is required to read the data files?
  4. What is the Projection/Spheroid of the LandScan data?
  5. What are the LandScan Dataset values?
  6. In the population database table, what does the field “Value” contain?
  7. In the population database table, what does the field “Count” mean?
  8. Can the previous versions of the LandScan Global Datasets be used to detect change over time?
  9. Can I download the input datasets used to develop the LandScan Dataset?
  10. Do the LandScan Global Population Datasets represent population count or population density?
  11. What data formats are used?
  12. Can I convert the LandScan Grid file to a shapefile?
  13. How do I calculate population density?
  14. How do I cite LandScan when I use the data in my publications?

02) "WARNING" Why are my national level population counts calculated significantly lower/higher than the published country numbers?

The LandScan Global grid cannot be projected into another coordinate system without a resampling of the data taking place (e.g. resulting in extra cells or data loss). It is possible that the user may not even be aware that they are changing the data if they bring the LandScan data into a projected view in the ESRI ArcMap environment. The data is reprojected and resampled "on the fly". In addition, special care must be taken to ensure that analysis cell size is set to match the LandScan data (e.g.0.008333333 degrees) and the analysis window is snapped to a cell interval extent. If using ArcMap, the user needs to bring in the LandScan data first (to set the projection) and then other data can be brought into this view for mensuration.

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03) What software is required to read the data files?

ESRI ArcView with the Spatial Analyst extension, ESRI ArcGIS with the Spatial Analyst extension, or ArcInfo will allow you to read and analyze the database files.
The data files can also be read by any software product that allows the user to import ESRI GRID-formatted data.

The data files are also provided the data in the ESRI Raster Binary format. Almost any programming language can read this file directly.
See also “What data formats are used?” below.

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04) What is the Projection/Spheroid of the LandScan data?

The LandScan Dataset is not projected, but can be used as a “Geographic” projection with various GIS software packages (e.g., ERDAS and ESRI). The data are referenced by latitude/longitude (WGS84) coordinates.

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05) What are the LandScan Dataset values?

The dataset values are people per cell.

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06) In the population database table, what does the field “Value” contain?

The "Value" field in the database table contains the number of people per cell. This is a population count per cell, not a population density.

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07) In the population database table, what does the field “Count” mean?

The “Count” field in the database table contains the number of cells that have the same population count as the cell of interest.


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08) Can the previous versions of the LandScan Global Datasets be used to detect change over time?

The data should not be used as a change detection or migration tool.

The reason we caution against a cell by cell comparison between LandScan database releases is that our input data sets are constantly improving which in turn cause changes in the population distribution. For instance, we often receive higher-resolution data depicting populated places (towns or villages) that did not exist in the digital representation of the area at a coarser scale. Of course the people were there all along, but may just "show up" in the latest version of our distribution. In other cases we may receive a more refined administrative boundary file which we use as a population control total boundary. These new boundaries may cause the population distribution within them to shift from an earlier version with a coarser boundary. In some cases we have found that the actual census counts associated with an administrative area may have been transposed with a nearby administrative area somewhere in the process before reaching us. Correcting these types of errors also cause the population distribution to shift. For these reasons we do not want our users to think that "migrations" are taking place where they are not.

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09) Can I download the input datasets used to develop the LandScan Dataset?

We are unable to distribute the datasets we use in the development of the LandScan Global Population Dataset. During the development of the population databases we use datasets that are provided by many sources and for which we have no redistribution rights.

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10) Do the LandScan Global Population Datasets represent population count or population density?

The LandScan datasets represent population count.

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11) What data formats are used?

ESRI grid format. The archive contains grids for the world and each of the six continents, excluding Antarctica. Each of the archive files contains two folders, an ArcInfo GRID folder and an INFO folder. Both folders must be extracted from the archive file into one new folder.

ESRI binary format. The archive contains contains raster binary data for the world and a rich text formatted file that describes the binary format. The binary raster file format is a simple format that can be used to transfer raster data among various applications. Almost any programming language can read this file directly.

For both formats, downloaded files need to be uncompressed using a standard Zip utility (e.g., WinZip, PKZIP, etc.) before they can be imported to GIS or other software. Users should expect a substantial increase in the size of downloaded data after uncompression. For additional information see the ReadMe file for 2010.

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12) Can I convert the LandScan Grid file to a shapefile?

We do not recommend converting the GRID data into a shapefile containing polygons because “people” are lost during the conversion. If users must convert the data from grid format to feature format, we recommend converting to a point file. This way each point represents the cell total as maintained in the GRID format.

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13) How do I calculate population density?

The links below contain instructions for calculating population density:

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14) How do I cite LandScan when I use the data in my publications?

This product was made utilizing the LandScan (insert dataset year)™ High Resolution global Population Data Set copyrighted by UT-Battelle, LLC, operator of Oak Ridge National Laboratory under Contract No. DE-AC05-00OR22725 with the United States Department of Energy.  The United States Government has certain rights in this Data Set.  Neither UT-BATTELLE, LLC NOR THE UNITED STATES DEPARTMENT OF ENERGY, NOR ANY OF THEIR EMPLOYEES, MAKES ANY WARRANTY, EXPRESS OR IMPLIED, OR ASSUMES ANY LEGAL LIABILITY OR RESPONSIBILITY FOR THE ACCURACY, COMPLETENESS, OR USEFULNESS OF THE DATA SET.

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Highlights

Mapping Technology Aids Tsunami Recovery. . .
Relief agencies assist victims of the Asian tsunami using a demographic database developed at ORNL.

 

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