Available datasets



The MODIS 500-m map of global urban extent
Center for Sustainability and the Global Environment, University of Wisconsin-Madison

 

1. Description of the dataset

The MODIS 500-m global map of urban extent was produced by Annemarie Schneider at the University of Wisconsin-Madison, in partnership with Mark Friedl at Boston Univeristy and the MODIS Land Group. The goal of this project was generate a current, consistent, and seamless circa 2001-2002 map of urban, built-up and settled areas for the Earth’s land surface. This work builds on previous mapping efforts using Moderate Resolution Imaging Spectroradiometer (MODIS) data at 1-km spatial resolution (Schneider et al., 2003; 2005), which was included as part of the MODIS Collection 4 (C4) Global Land Cover Product (Friedl et al., 2002). Here we addressed weaknesses in the first map as well as several limitations of contemporary global urban maps by developing a methodology that relies solely on newly released Collection 5 (C5) MODIS 500-m resolution data. Specifically, a supervised decision tree classification algorithm was used to map urban areas using region-specific parameters (see Schneider et al., 2009; 2010 for full details on methodology).

The map described here serves as the first stage in our development of a comprehensive database of urban land surface characteristics for 2001-2010. Recent research efforts and feedback from the user community have indicated that finer resolution data and sub-pixel information is needed. Our ongoing efforts are focused on: (1) creating updated maps of urban extent circa 2005-2006 and 2009-2010; (2) creating global maps that provide sub-pixel estimates of urban land use and vegetation; and (3) providing a more refined suite of land surface characteristics for urban areas by differentiating core downtown areas from low density residential areas. In addition, we hope to build on these results to create a globally consistent, validated map of “hot spots” of land cover change in rapidly developing metropolitan areas. Please check back for new developments on these projects in the coming year.

The intended audience for the MODIS 500-m map of urban extent is primarily the academic research community working at regional to global scales on questions related to the geophysical environment; please keep this in mind as you put the data to use.

2. Citing the dataset

We are happy to offer the data free of charge, but we ask that you cite the following publications when you utilize the data:

Schneider, A., M. A. Friedl and D. Potere (2009) A new map of global urban extent from MODIS data. Environmental Research Letters, volume 4, article 044003.

Schneider, A., M. A. Friedl and D. Potere (2010) Monitoring urban areas globally using MODIS 500m data: New methods and datasets based on urban ecoregions. Remote Sensing of Environment, vol. 114, p. 1733-1746.

3. Additional publications

For more information on the accuracy assessment campaign for global urban maps, please see:

Potere, D., A. Schneider, S. Angel, and D. Civco (2009) Mapping urban areas on a global scale: which of the eight maps now available is more accurate? International Journal of Remote Sensing, volume 30, pages 6531-6558.

Potere, D. and A. Schneider (2007) A critical look at representations of urban areas in global maps. Geojournal , Special Issue on Population Distribution, volume 69, pages 55-80.

If you would like additional information on the MODIS Global Land Cover Map, please see the following publications:

Friedl, M. A., D. K. McIver, J. C. F. Hodges, Z. Y. Zhang, D. Muchoney, A. H. Strahler, C. E. Woodcock, S. Gopal, A. Schneider, A. Cooper, A. Baccini, F. Gao, C. Schaaf (2002) Global land cover mapping from MODIS: algorithms and early results. Remote Sensing of Environment, volume 83, pages 287-302.

Friedl, M.A., D. Sulla-Menashe, B. Tan, A. Schneider, N. Ramankutty, and A. Sibley (2010) MODIS Collection 5 Global Land Cover: algorithm refinements and characterization of new datasets. Remote Sensing of Environment, volume 114, pages 168-182.

For information on the MODIS 1-km map of Urban Extent (the foundational work for the 500-m map), please see:

Schneider, A., M. A. Friedl, D. K. McIver, and C. E. Woodcock (2003) Mapping urban areas by fusing multiple sources of coarse resolution remotely sensed data. Photogrammetric Engineering and Remote Sensing, volume 69, pages 1377-1386.

Schneider, A., M. A. Friedl, and C. E. Woodcock (2005) Mapping urban areas by fusing multiple sources of coarse resolution remotely sensed data: global results, in Proceedings of the 5 th International Symposium of Remote Sensing of Urban Areas, Tempe, Arizona, March 14-16, 2005.

4. Characteristics of the data

Data format: raster image structure, generic binary format (also called ENVI Standard)

Geographic extent: global; dimensions vary

Data size: 8-bit data, roughly 3.5 gigabytes unzipped

The data is formatted for ENVI software and will open in ArcGIS if the header file is provided. Projection information may have to be set in ArcGIS (or other software) depending on the projection. For coordinate system parameters, see below.

5. Definition of urban areas and land cover classes

The data are provided for two different classification schemes:

Global Urban Extent (class 13), including land (class 1) and water (class 0) information

Global IGBP Land Cover Map (classes 1-17), including urban extent (class 13)

a. Urban areas

In both datasets, urban areas (coded class 13) are defined based on physical attributes: urban areas are places that are dominated by the built environment. The ‘built environment’ includes all non-vegetative, human-constructed elements, such as buildings, roads, runways, etc. (i.e. a mix of human-made surfaces and materials), and ‘dominated’ implies coverage greater than or equal to 50 percent of a given landscape unit (here, the pixel). Pixels that are predominantly vegetated (e.g. a park) are not considered urban, even though in terms of land use, they may function as urban space. Although ‘impervious surface’ is often used to characterize urban areas within the remote sensing literature, we prefer the more direct term ‘built environment’ because of uncertainty and scaling issues surrounding the impervious surface concept. Finally, we also define a minimum mapping unit: urban areas are contiguous patches of built-up land greater than 1 km 2.

b. Land cover classes

In the global land cover map, the classes are defined according to the International Geosphere-Biosphere Programme (IGBP) 17-class scheme shown in Table 1.

No.

Class name

Description

 

 

 

1

Evergreen Needleleaf Forest

Lands dominated by woody vegetation with a percent cover > 60% and height exceeding 2 meters.  Almost all trees remain green all year. Canopy is never without green foliage.

2

Evergreen Broadleaf Forest

Lands dominated by woody vegetation with a percent cover > 60% and height exceeding 2 meters.  Almost all trees remain green year round. Canopy is never without green foliage.

3

Deciduous Needleleaf Forest

Lands dominated by woody vegetation with a percent cover > 60% and height exceeding 2 meters. Trees shed their leaves during the dry season; e.g. Siberian Larix.

4

Deciduous Broadleaf Forest

Lands dominated by woody vegetation with a percent cover > 60% and height exceeding 2 meters. Consists of broadleaf trees with an annual cycle of leaf-on and leaf-off periods.

5

Mixed Forests

Lands dominated by woody vegetation with a percent cover > 60% and height exceeding 2 meters. Consists of mixtures of either broadleaf or needleleaf trees and in which neither component exceeds 60% of landscape.

6

Closed Shrublands

Lands with woody vegetation with a height less than 2 meters. The total percent cover, including the herbaceous understory, exceeds 60%. The shrub foliage can be either evergreen or deciduous.

7

Open Shrublands

Lands with woody vegetation with a height less than 2 meters, and sparse herbaceous understory. Total percent cover is less than 60%. The shrub foliage can be either evergreen or deciduous.

8

Woody Savannas

Lands with and herbaceous understory, typically graminoids, and with tree and shrub cover between 30-60%. The tree and shrub cover height exceeds 2 meters.

9

Savannas

Lands with an herbaceous understory, typically graminoids, and with tree and shrub cover between 10-30%. The tree and shrub cover height exceeds 2 meters.

10

Grasslands

Lands with herbaceous types of cover, typically graminoids. Tree and shrub cover is less than 10%.

11

Permanent Wetlands

Lands with a permanent mosaic of water and herbaceous or woody vegetation. The vegetation can be present in either salt, brackish, or fresh water. Only wetlands covering extensive areas (i.e., more than 500 km2) will be mapped (e.g., Sud, Okavanga, Everglades).

12

Croplands 

Lands where crops comprise > 60% of the total land cover.

13

Urban Areas 

See (a) above.

14

Cropland - Natural Vegetation Mosaic

Lands with mosaics of crops and other land cover types in which no component comprises more than 60% of the landscape.

15

Snow and Ice

Lands under snow/ice cover for most of the year.

16

Barren or Sparsely Vegetated

Lands with exposed soil, sand or rocks and has less than 10% vegetated cover during any time of the year.

17

Water Bodies

 

Oceans, seas, lakes, reservoirs, and rivers. Can be either fresh or salt water bodies.  Coded as 0 in the MODIS-based maps.

Note:  The number column refers to the digital number value in the raster dataset. 

6. Data dimensions and projection parameters

The data are provided in three different projected coordinate systems. The following information is also located in the header file (e.g. image.hdr) associated with each map.

Native Sinusoidal projection

Columns = 86400
Rows = 43196
Pixel size = 463.312714 meters
Layers = 1
Data size = 1 Byte
Upper left x, y = -20015109.354000,10007554.677000 meters
Lower right x, y = 20015106.711349,-10005238.113297 meters
Projection = Sinusoidal
Spheroid = Sphere of Radius 6371007.181 meters (i.e. GRS 1980 authalic sphere)
False easting = 0
False northing = 0
Central meridian = 0
Latitude of origin = 0
Notes: In ArcGIS, the projected coordinate system World Sinusoidal can be used, but the Geographic Coordinate System must be modified to a GRS 1980 authalic sphere (under spheroid).

Geographic projection (latitude, longitude)

Columns = 86400
Rows = 43200
Pixel size = 0.00416667 degrees (15.0000 arc-seconds)
Layers = 1
Data size = 1 Byte
Upper left x, y = -180.00000, 90.00000 degrees (-648000.0000,324000.0000 arc-seconds)
Lower right x, y = 180.00000, -89.979167 degrees (647985.0000,-323985.0000 arc-seconds)
Projection = Geographic
Spheroid = Sphere of Radius 6370997 meters (i.e. Clarke 1866 authalic sphere, or Authalic sphere (ARCINFO))
False easting = 0
False northing = 0
Central meridian = 0
Latitude of origin = 0
Notes: In ArcGIS, this dataset will open with the default coordinate system WGS 1984. For correct alignment, the projection information should be set to the geographic coordinate system Clarke 1866 authalic sphere (under spheroid).

Interrupted Goode’s Homolosine projection

Columns = 86400
Rows = 37442
Pixel size = 463.312714 meters
Layers = 1 Data size = 1 Byte
Upper left x, y = -20015109.354000,8673553.108578 meters
Lower right x, y = 20015107.740445,-8673422.693144 meters
Projection = Interrupted Goode's Homolosine
Spheroid = Sphere of Radius 6371007.181 meters (i.e. GRS 1980 authalic sphere)
False easting = 0
False northing = 0
Central meridian = 0
Latitude of origin = 0
Notes: In ArcGIS, the projected coordinate system World Goode Homolosine Land can be used, but the Geographic Coordinate System must be modified to a GRS 1980 authalic sphere (under spheroid).

Important notes:

The upper left x, y and lower right x, y values are associated with the center of the pixel. Different software packages define coordinate information as either the center or the edge of a pixel; please see specific software documentation for details.

7. Reliability and accuracy of the data

The MODIS 500-m map of global urban extent has undergone a rigorous assessment of accuracy prior to its public release. The results of this investigation are described fully in Schneider et al., 2009; 2010; Potere & Schneider, 2007; 2009).

8. Downloading the data

All data are available for download at:

http://www.sage.wisc.edu/people/schneider/research/data.html

To access the data:

1. Send an email to aschneider4@wisc.edu. Please include:

  •  a description of how you will use the data, and
  •  your contact information.

2. You will receive an email within 1-3 days with the password for data access.

3. Click on the links to the maps at

http://www.sage.wisc.edu/people/schneider/research/data.html,

…or to access the data website directly, click here. Enter the password information.

4. Download the files and the readme information. Note that the size of the zipped dataset is 12-100 mb, but upon unzipping is roughly 3.5 gigabytes.

9. Contact information

All comments, questions and concerns should be directed to:

Annemarie Schneider
Assistant Professor, Center for Sustainability and the Global Environment,
Nelson Institute for Environmental Studies and Department of Geography
University of Wisconsin-Madison
1710 University Avenue, Room 264, Madison, Wisconsin 53726 USA
aschneider4@wisc.edu

 

 

 

 



       

Updated: 7/01/2010

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