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land surface, radiance or imagery, Maine, environment, urbanization, USA, runoff, impervious area, land use/land cover, imageryBaseMapsEarthCover
IMPERV quantifies impervious features at a 5 meter spatial resolution over the State of Maine.
IMPERV is a raster data set of impervious areas, derived from 5 meter SPOT imagery collected in the summer of 2004 over the State of Maine. IMPERV is part of a larger mapping initiative by the State of Maine to quantify land cover (MELCD) at a 5 meter resolution over the entire state. Areas of imperviousness are characterized by anthropogenic features such as buildings, roads, parking lots, etc. Pixel values of 0 (zero) indicate an impervious land cover, while pixel values of 1 (one) indicate pervious land cover features.
Credit should always be given to the data source and/or originator(s) when the data is transferred or printed.
Users must assume responsibility in determining the usability of this data for their purposes. Digital maps retain the accuracy of their source materials. The best use of data mapped at scales of 1:500,000 and 1:250,000 is in statewide planning and studies; at 1:100,000 in regional planning and studies; at 1:62,500 and 1:24,000 in detailed studies and local planning; and at 1:12,000 and 1:5,000 or larger scales in parcel level studies and detailed local planning. In the use of Maine GIS data, please check sources, scale, accuracy, currentness and other available information. Please confirm that you are using the correct copy of both data and metadata from the Maine GIS Data Catalog. Updates, corrections, and feedback, incorporated in the Maine GIS database are made in accordance with "Data Standards for Maine Geographic Information Systems", 2002 and coordinated by MEGIS
Extent
There is no extent for this item.
Maximum (zoomed in) | 1:5,000 |
Minimum (zoomed out) | 1:150,000,000 |
A spread sheet IMPERV5M.xls distributed with IMPERV provides error assessment results based on the stratified random selection of 298, 25m2 validation samples.
Credit should always be given to the data source and/or originator(s) when the data is transferred or printed.
publication date
Users must assume responsibility to determine the usability of this data for their purposes. Although these data have been processed successfully on a computer system at the Maine Office of Geographic Information Systems, no warranty expressed or implied is made by MEGIS regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. Neither the Maine Office of Geographic Information Systems, nor any of its contributors, is liable for misuse of the data, for damage, for transmission of viruses, or for computer contamination through the distribution of these data sets.
Users must assume responsibility to determine the usability of this data for their purposes.
Users must assume responsibility in determining the usability of this data for their purposes. Digital maps retain the accuracy of their source materials. The best use of data mapped at scales of 1:500,000 and 1:250,000 is in statewide planning and studies; at 1:100,000 in regional planning and studies; at 1:62,500 and 1:24,000 in detailed studies and local planning; and at 1:12,000 and 1:5,000 or larger scales in parcel level studies and detailed local planning. In the use of Maine GIS data, please check sources, scale, accuracy, currentness and other available information. Please confirm that you are using the correct copy of both data and metadata from the Maine GIS Data Catalog. Updates, corrections, and feedback, incorporated in the Maine GIS database are made in accordance with "Data Standards for Maine Geographic Information Systems", 2002 and coordinated by MEGIS
Sanborn Solutions - www.sanborn.com
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value attribute table
Environmental Systems Research Institute, Inc. (ESRI)
Sanborn Solutions - www.sanborn.com
IMPERV is a raster data set of impervious areas, derived from 5 meter SPOT imagery collected in the summer of 2004 over the State of Maine. IMPERV is part of a larger mapping initiative by the State of Maine to quantify land cover (MELCD) at a 5 meter resolution over the entire state. Areas of imperviousness are characterized by anthropogenic features such as buildings, roads, parking lots, etc. Pixel values of 0 (zero) indicate an impervious land cover, while pixel values of 1 (one) indicate pervious land cover features.
IMPERV quantifies impervious features at a 5 meter spatial resolution over the State of Maine.
A spread sheet IMPERV5M.xls distributed with IMPERV provides error assessment results based on the stratified random selection of 298, 25m2 validation samples.
publication date
None
Users must assume responsibility in determining the usability of this data for their purposes. Digital maps retain the accuracy of their source materials. The best use of data mapped at scales of 1:500,000 and 1:250,000 is in statewide planning and studies; at 1:100,000 in regional planning and studies; at 1:62,500 and 1:24,000 in detailed studies and local planning; and at 1:12,000 and 1:5,000 or larger scales in parcel level studies and detailed local planning. In the use of Maine GIS data, please check sources, scale, accuracy, currentness and other available information. Please confirm that you are using the correct copy of both data and metadata from the Maine GIS Data Catalog. Updates, corrections, and feedback, incorporated in the Maine GIS database are made in accordance with "Data Standards for Maine Geographic Information Systems", 2002 and coordinated by MEGIS
Credit should always be given to the data source and/or originator(s) when the data is transferred or printed.
This data set was assessed based on the stratified random selection of 298, 25m2 validation samples. For a map at 90% accuracy using a 95% confidence level, the minimum number of sites required will be 298; with the map being rejected if more than 21 are misclassified. Each validation point was photo-interpreted by an analyst to determine its validation call (impervious or pervious) and to ensure that its entire area was a homogenous cover type. The cover type was determined by examining the SPOT imagery in conjunction with existing DOQQ imagery as further reference. A total of 16 validation points were deemed to be incorrect.
Sanborn has developed an efficient procedure to assess accuracy of the impervious classification. The desired map accuracy is 90% for a MMU of 0.89 acres. Since we are working with a two-case situation where we only wish to know whether the classification is right or wrong, we can use a binomial distribution to calculate the sample size. Using this assumption, we can use Ginevan (1978) who illustrates a sampling method using stratified random points that satisfies three criteria:
o the scheme should have a low probability of accepting a map of low accuracy.
o it should have a high probability of accepting a map of high accuracy.
o it should require a minimum number of ground truth samples.
Using the look-up table given in the paper that presents the required sample size for a given minimum error and a desired level of confidence, we have determined a specific number of points that are required to meet the accuracy specification. For a map at 90% accuracy using a 95% confidence level (at 95%, we run the risk of a 1 in 20 chance that we reject a map that is actually correct), the minimum number of sites required will be 298; with the map being rejected if more than 21 are misclassified.
Data set is complete for the State of Maine.
The SPOT data source for IMPERV specifies a positional (horizontal) accuracy 12 meters or better with 90% confidence.
Data was derived from digital data that meets or exceeds National Map Accuracy Standards for 1:24,000 scale.
IMPERV was derived from 5 meter SPOT imagery collected in the summer of 2004 over the State of Maine.
IMPERV was derived from 5 meter SPOT imagery collected in the summer of 2004 over the State of Maine. IMPERV is part of a larger mapping initiative by the State of Maine to quantify land cover at a 5 meter resolution over the entire state.
Areas of imperviousness are characterized by anthropogenic features such as buildings, roads, parking lots, etc. Pixel values of 1 (one) indicate a pervious land cover, while pixel values of 0 (zero) indicate impervious land cover features.
Sanborn Solutions - www.sanborn.com
Several coastal areas (mostly islands) which were missing partial or complete data updated. The South Bristol area was one of the fixes.
A limited amount of hand editing was done in Old Orchard Beach to fix localized errors.
A limited amount of hand editing was done in Thomaston to fix localized errors.
IMPERV pixel values of 0 (zero) indicate an impervious land cover, while pixel values of 1 (one) indicate pervious land cover features.
The ArcView shapefile and ArcGIS geodatabase formats, commonly used for Maine GIS data, carry default identifiers and attributes that are software generated and/or important for internal recordkeeping. These are listed here to avoid repetition for every layer, and may not be repeated in the attribute descriptions and definitions of each layer. Common software generated identifiers and attributes in Maine GIS data include: FID (feature identifier), Shape (feature geometry), OBJECTID and SHAPE_lengt. In addition, most GIS formats will carry fields for PERIMETER, AREA and/or LENGTH according to feature geometry. These fields are typically available by default, with the units based on coordinate system or projection units of GIS data. Most GIS software packages also provide a means to calculate these values. It is important to test any columns containing PERIMETER, AREA or LENGTH values before using them for analysis purposes. These important values can be carried from format to format and become out-dated. Verify that the values are correct. Also, in your GIS software, please view the properties of data layers for the map units used to calculate these fields, and for the units set for display purposes.
Users must assume responsibility to determine the usability of this data for their purposes. Although these data have been processed successfully on a computer system at the Maine Office of Geographic Information Systems, no warranty expressed or implied is made by MEGIS regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. Neither the Maine Office of Geographic Information Systems, nor any of its contributors, is liable for misuse of the data, for damage, for transmission of viruses, or for computer contamination through the distribution of these data sets.
These data are available to Internet browsers for download from the Maine GIS Internet Data Catalog - http://megis.maine.gov/catalog/
Data available from this website is in .zip compressed format. WinZip is a Windows based, PKZip-compatible compression utility. You will need a program like this to extract the data. A link to a trial copy WinZip software is available at http://megis.maine.gov/links/
If you are not already a GIS user, free software for viewing these files is available from Environmental Systems Research Institute, Inc. (ESRI) - www.esri.com
See http://megis.maine.gov/links/ for a link to ArcExplorer 9.x .
Users must assume responsibility to determine the usability of this data for their purposes. Although these data have been processed successfully on a computer system at the Maine Office of Geographic Information Systems, no warranty expressed or implied is made by MEGIS regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. Neither the Maine Office of Geographic Information Systems, nor any of its contributors, is liable for misuse of the data, for damage, for transmission of viruses, or for computer contamination through the distribution of these data sets.
These data are available to Internet browsers for download from the Maine GIS Internet Data Catalog. Data available from this website is in .zip compressed format. WinZip is a Windows based, PKZip-compatible compression utility. You will need a program like this to extract the data. A link to a trial copy WinZip software is available at http://megis.maine.gov/software.asp.
Users must assume responsibility to determine the usability of this data for their purposes.
Please contact the Maine Office of GIS (MEGIS) for access instructions.
Sanborn Solutions - www.sanborn.com