Metro Canopy Cover, 1998 Metadata

Canopy Cover, 1998 - Coverage version
	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

IDENTIFICATION INFORMATION

1.1

Citation

Originator

Metro Data Resource Center

The classification and mapping of urban forest canopy cover was accomplished using Landsat TM digital satellite imagery. Landsat TM data includes spectral reflectance information from the visible, near-infrared, and middle-infrared portions of the spectrum and has a resampled spatial resolution of 25-meters. Tthe wide range spectral information contained in Landsat TM data makes it ideal for classifying vegetation such as forest canopy cover. Moreover, Landsat TM data was used to produce the original 1991-based land cover map for the Portland area. As described in the following section, the 1998 Landsat TM scene was also utilized in the development of the 1998-revised land cover map. These forest canopy cover classes were selected due to the proven ability of Landsat TM imagery to effectively discriminate this level of forest cover detail. In addition, other vegetation cover mapping projects in and surrounding the Willamette Valley have used these same or similar cover class discriminations. Unsupervised classification techniques were used to discriminate and map forest canopy cover. The goal in any image classification project is to determine when the image is a good predictor of the vegetative characteristic of interest, such as forest canopy cover. ERDAS Imagine digital image processing software was utilized to stratify the Landsat TM imagery into approximately 150 spectral classes based solely on the spectral information in the image data set. Spectral responses in the imagery, aerial photo and digital orthophotography interpretation, and ancillary GIS data were utilized to determine which spectral classes represent forested areas and subsequently to categorize each forested spectral class into the appropriate canopy cover class. For instance, 51 to 75% tree canopy cover in a residential area is categorized into the same class as an area of 51 to 75% forest canopy cover in a natural area.

Purpose

To determine the pattern of canopy cover within the Portland metropolitan area. Not appropriate to use or analyze this data at the pixel level. Most useful when used on an aggregate basis.

Supplemental information

The TIFF on RLIS Lite includes an HTML document with a corresponding name as a legend.

1.3

Time period of content

Maintenance/update frequency

Urban Clackamas County, Multnomah County, and Washington County, Oregon

West bounding coordinate

-123.15156069

East bounding coordinate

-122.31651100

North bounding coordinate

45.70263875

South bounding coordinate

45.23396470

1.6

Keywords

Theme keyword thesaurus

None

Theme keyword

vegetation, canopy cover, forest, urban forest, crown cover

Place keyword thesaurus

None

Place keyword

Portland, Multnomah County, Washington County, Clackamas County, Oregon

These data are sold under the agreement that the user may use the data in its business activity and for no other purpose whatsoever. User shall not allow access to the data by any other person or organization, unless authorized in writing by the Metro DRC or, if the other party is a contractor providing services to a government requiring usage of the data in order to provide contractual services.
User shall not duplicate the data except for the following:
(1) User may make one backup copy of the data, and
(2) User may translate the data into other formats and/or media.
For full product purchase agreement that accompanies these data, please see http://storefront.metro-region.org/drc/rlislite/subscribe/license.cfm

1.10

Browse graphic

Browse graphic file name

Browse graphic file description

Browse graphic file type

1.13

Native data set environment

Shape file: Canopy98.tif
Cover name: $GRIDS/environ/canopy98
Software/hardware: ArcInfo 8.1 on NT workstation.
ArcSDE 8.1 on Compaq Alpha 4100. Tru64 5.0 OS.

[Top of Page]

DATA QUALITY INFORMATION

2.4

Horizontal positional accuracy

[Top of Page]

SPATIAL DATA ORGANIZATION INFORMATION

3.2

Direct spatial reference method

Raster

3.3

Point and vector object information

SDTS point and vector object type

Point and vector object count

3.4

Raster object information

SPATIAL REFERENCE INFORMATION

4.1

Horizontal Coordinate System

Grid coordinate system name

State plane coordinate system 1983.

SPCS zone identifier

5076

Planar distance units

International feet

Horizontal datum name

North American Datum of 1983/1991 (HPGN)

[Top of Page]

ENTITY AND ATTRIBUTE INFORMATION

5.2

Overview description

Table Name	Column	Sample Domain Value	Definition
Canopy98.vat	--	--	Urban canopy cover value attribute table
	Value	--	Percent Canopy Coverage
		1	0 - 25% forest canopy cover
		2	26 - 50% forest canopy cover
		3	51 - 75% forest canopy cover
		4	76 = 100% forest canopy cover