Impervious Surface Area 1991 - TCMA Metadata

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Impervious Surface Area 1991 - TCMA


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Metadata Summary

Originator Remote Sensing and Geospatial Analysis Laboratory, University of Minnesota
Abstract Landsat Thematic Mapper data have been used to classify and map impervious surface area for the TCMA area for 1986, 1991, 1998 and 2002. Impervious area is mapped as a continuous variable from 0 to 100 percent for each 30-meter pixel.
Browse Graphic View a sample of the data
Time Period of Content Date
Currentness Reference 04 September, 1991
Access Constraints The Remote Sensing and Geospatial and Analysis Laboratory, University of Minnesota, has attempted to produce accurate maps, statistics and information of land cover and impervious surface area. However, it makes no representation or warranties, either expressed or implied, for the data accuracy, currency, suitability or reliability for any particular purpose. Although every effort has been made to ensure the accuracy of information, errors and conditions originating from the source data and processing may be present in the data supplied. Users are reminded that all geospatial maps and data are subject to errors in positional and thematic accuracy. The user accepts the data “as is” and assumes all risks associated with its use. The University of Minnesota and the Metropolitan Council assume no responsibility for actual or consequential damage incurred as a result of any user's reliance on the data. The data are the intellectual property of the University of Minnesota.
Use Constraints This data may be used for educational and non-commercial purposes, provided proper attribution is given. Secondary distribution of the data is permitted, but not supported by the University of Minnesota. By accepting the data, the user agrees not to transmit this data or provide access to it or any part of it to another party unless the user includes with the data a copy of this disclaimer.
Distributor Organization Remote Sensing and Geospatial Analysis Lab, Univeristy of Minnesota
Ordering Instructions see website or contact info
Online Linkage Click here to download data. (See Ordering Instructions above for details.) By clicking here, you agree to the notice in "Distribution Liability" in Section 6 of this metadata.


Full metadata for Impervious Surface Area 1991 - TCMA


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1. Identification_Information
2. Data_Quality_Information
3. Spatial_Data_Organization_Information
4. Spatial_Reference_Information
5. Entity_and_Attribute_Information
6. Distribution_Information
7. Metadata_Reference_Information


Section 1 Identification Information Top of page
Originator Remote Sensing and Geospatial Analysis Laboratory, University of Minnesota
Title Impervious Surface Area 1991 - TCMA
Abstract Landsat Thematic Mapper data have been used to classify and map impervious surface area for the TCMA area for 1986, 1991, 1998 and 2002. Impervious area is mapped as a continuous variable from 0 to 100 percent for each 30-meter pixel.
Purpose Map and quantify the amount of impervious surface in the selected region.
Time Period of Content Date
Currentness Reference 04 September, 1991
Progress Complete
Maintenance and Update Frequency None planned
Spatial Extent of Data Twin Cites Metro Area, Minnesota
Bounding Coordinates -93.685183
-93.631305
45.252953
45.220512
Place Keywords TCMA, Minnesota
Theme Keywords
Theme Keyword Thesaurus
Access Constraints The Remote Sensing and Geospatial and Analysis Laboratory, University of Minnesota, has attempted to produce accurate maps, statistics and information of land cover and impervious surface area. However, it makes no representation or warranties, either expressed or implied, for the data accuracy, currency, suitability or reliability for any particular purpose. Although every effort has been made to ensure the accuracy of information, errors and conditions originating from the source data and processing may be present in the data supplied. Users are reminded that all geospatial maps and data are subject to errors in positional and thematic accuracy. The user accepts the data “as is” and assumes all risks associated with its use. The University of Minnesota and the Metropolitan Council assume no responsibility for actual or consequential damage incurred as a result of any user's reliance on the data. The data are the intellectual property of the University of Minnesota.
Use Constraints This data may be used for educational and non-commercial purposes, provided proper attribution is given. Secondary distribution of the data is permitted, but not supported by the University of Minnesota. By accepting the data, the user agrees not to transmit this data or provide access to it or any part of it to another party unless the user includes with the data a copy of this disclaimer.
Contact Person Information Marvin Bauer, Professor
Remote Sensing and Geospatial Analysis Lab, Univeristy of Minnesota
1530 Cleveland Avenue North
St. Paul , MN 55108
Phone: (612)624-3703
Fax: (612)625-5212
Email : mbauer@umn.edu
Browse Graphic View a sample of the data
Browse Graphic File Description
Associated Data Sets Available years: 1986, 1991, 1998 or 2002

Section 2 Data Quality Information Top of full metadata Top of page
Attribute Accuracy The agreement between Landsat estimates and measurements of impervious made from high resolution aerial images was R-Square = 0.9200
Logical Consistency
Completeness Data provides complete coverage over the stated extent of the data.
Horizontal Positional Accuracy RMS Error is 0.25 - pixel or <7.5 meters
Vertical Positional Accuracy RMS Error is 0.25 - pixel or <7.5 meters
Lineage
The process is generally described as follows. The imagery was rectified to the UTM coordinate and projection system. A combination of spring and summer dates of Landsat data for each year (1986, 1991, 1998 or 2002) was used to classify the land cover types into urban/developed vs. rural (agricultural, forest, and wetland) and water classes. Measurements of impervious surface area were made on high resolution aerial imagery for a random sample of areas for calibration of the Landsat classification model. The calibration sites were used to develop a least squares model relating percent impervious to the spectral-radiometric response of the Landsat TM data for the summer image of each year. The particular Landsat parameter used to estimate percent impervious was "tasseled cap" greenness which is sensitive to the amount of green vegetation and therefore is inversely related to the amount of impervious surface area. The regression model was used to estimate the amount of impervious surface within the area of each pixel. After applying the regression model to the Landsat TM image the land cover classification was used to assign all non-urban areas a zero percent impervious value. Accuracy assessment of the Landsat derived impervious surface estimates was performed with a second independent sample of measurements of impervious from the aerial imagery. Accuracy assessment was based on the linear fit of actual versus predicted impervioius surface.

Image processing:

Impervious surface classification was performed with a Landsat TM satellite image (path: 27 row:28/29) acquired on 04 September, 1991. The imagery was rectified to the UTM coordinate and projection system to an RMS error of 0.25 pixel (<7.5-meters) using 25 ground control points. The base layer used was the MNDOT Major Roads map. Nearest neighbor resampling to a 30-meter pixel size and the coordinates of the final image were adjusted to values evenly divisible by 30. Following rectification the imagery was transformed to tasseled cap values using ERDAS Imagine default processes. The tasseled cap data were stretched to unsigned 8-bit.

Impervious Model Calibration Data:

Model calibration sites were randomly selected and high resolution aerial imagery were used to determine the amount of impervious surface within each calibration site. 53 sites, distributed across the image area, were collected for each image. Imperious surface area was determined from the 1991 DOQQ's of 1-meter resolution. Percent impervious surface area was calculated for each site.

Modeling Impervious Surface Area:

The measurements of impervious surface area from the calibration sites were used to develop a least squares regression model relating percent impervious to the spectral-radiometric response of the Landsat TM data. The Landsat parameter used to estimate percent impervious was tasseled cap greenness which is sensitive to the amount of green vegetation and therefore is inversely related to the amount of impervious. The regression model used for the 04 September, 1991 Landsat TM image was:

Percent Impervious Surface = 48.35453 - 1.8741616*(tasseled cap greenness) + 0.0043972*(tasseled cap greenness-2.8306)^2

R-Square: 0.85999999999999999, Adjusted R-Square: 0.84999999999999998, Root Mean Square Error: 11.33, Observations: 53

Accuracy Assessment/ Inverse Calibration:

To measure the accuracy of the Landsat-derived impervious surface estimates, an independent sample of 104 accuracy assessment sites were selected. The sites were randomly selected and compared with high resolution aerial imagery to determine the amount of impervious surface within each accuracy assessment sites. Accuracy was determined with a plot of actual vs. predicted plots and results were as follows:

Linear Fit: Predicted Percent Impervious Surface Area = 3.4995858 + 0.9009355*(Actual Percent Impervious Surface Area)

R-Square: 0.92000000000000004, Adjusted R-Square: 0.92000000000000004, Root Mean Square Error: 8.5999999999999996, Observations: 104

To remove model bias an inverse calibration was computed from the linear fit of the actual vs. predicted plot and applied to the impervious surface classification. The inverse equation (Actual Percent Impervious Surface Area = (3.4995858 - Predicted Percent Impervious Surface Area)/0.9009355). Accuracy of Landsat derived impervious surface estimates was reassessed following the inverse calibration. The results follow: Linear Fit:

Predicted Percent Impervious Surface Area = -1.070047 + 0.9755037*(Actual Percent Impervious Surface Area)

R-Square: 0.92000000000000004, Adjusted R-Square: 0.92000000000000004, Root Mean Square Error: 8.5999999999999996, Observations: 104

Although, the inverse calibration did not affect the R-Square and the RMSE increased, the bias is removed. This is apparent from the reduction in the intercept and an increase in the slope.

Removing Non-Urban Areas:

This step identified non-urban areas within the Landsat image area and reclassified these areas in the impervious surface classification with a percent impervious surface value of zero. To identify non-urban areas a combination of spring and summer dates of Landsat imagery, taken in 1991, were used to classify the land cover types into urban/developed vs. rural (agricultural, forest, and wetland) and water classes. Classification accuracy, for the TCMA, MN region, had producers and users accuracies of 96% and 98.2%, respectively, for the urban class and an overall classification accuracy 94.599999999999994% with a Kappa statistic of 0.93. As an additional step urban areas from previous years were added to the current year (i.e. the 1998 classified urban area would be added to the 1991 and 1986 classified urban areas). The final impervious surface classification was then overlaid with the land cover classification and areas identified as non-urban were reclassified with a percent impervious surface value of zero.

Limiting to MCD Boundaries:

The final impervious surface classification was then clipped to match the boundaries of the MCD of interest. Geospatial data used to identify MCD boundaries was acquired from the Minnesota Legislative GIS office, <ftp://ftp.commissions.leg.state.mn.us/pub/gis/shape/mcd2003.zip>.

Source Scale Denominator

Section 3 Spatial Data Organization Information Top of full metadata Top of page
Native Data Set Environment ERDAS Imagine 8.6
Geographic Reference for Tabular Data
Spatial Object Type Raster
Vendor Specific Object Types
Tiling Scheme

Section 4 Spatial Reference Information Top of full metadata Top of page
Horizontal Coordinate Scheme Universal Transverse Mercator
Ellipsoid Geodetic Reference System 80
Horizontal Datum NAD83
Horizontal Units Meters
Distance Resolution 30
Altitude Datum Not applicable
Depth Datum Not applicable
Cell Width 30.000000
Cell Height 30.000000
UTM Zone Number 15

Section 5 Entity and Attribute Information Top of full metadata Top of page
Entity and Attribute Overview The pixel values represent the area (in percent) of completely impervious surface within the 30-m by 30-m pixel area. Values range from 0 to 100 percent.
Entity and Attribute Detailed Citation

Section 6 Distribution Information Top of full metadata Top of page
Publisher Remote Sensing and Geospatial Analysis Lab, Univeristy of Minnesota
Publication Date
Contact Person Information Marvin Bauer, Professor
Remote Sensing and Geospatial Analysis Lab, Univeristy of Minnesota
1530 Cleveland Avenue North
St. Paul , MN 55108
Phone: (612)624-3703
Fax: (612)625-5212
Email: mbauer@umn.edu
Distributor's Data Set Identifier impervious_tcma_04sep1991_inverse_masked8691.img
Distribution Liability This data may be used for educational and non-commercial purposes, provided proper attribution is given. Secondary distribution of the data is permitted, but not supported by the University of Minnesota. By accepting the data, the user agrees not to transmit this data or provide access to it or any part of it to another party unless the user includes with the data a copy of this disclaimer.
Transfer Format Name GeoTIFF
Transfer Format Version Number
Transfer Size 11 MB
Ordering Instructions see website or contact info
Online Linkage Click here to download data. (See Ordering Instructions above for details.) By clicking here, you agree to the notice in "Distribution Liability" in Section 6 of this metadata.

Section 7 Metadata Reference Information Top of full metadata Top of page
Metadata Date
Contact Person Information Marvin Bauer, Professor
Remote Sensing and Geospatial Analysis Lab, Univeristy of Minnesota
1530 Cleveland Avenue North
St. Paul , MN 55108
Phone: (612)624-3703
Fax: (612)625-5212
Email: mbauer@umn.edu
Metadata Standard Name Minnesota Geographic Metadata Guidelines
Metadata Standard Version 1.2
Metadata Standard Online Linkage http://www.gis.state.mn.us/stds/metadata.htm


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