Source:  dot97c

ODOT

Copied from EC90, augmented by TeleAtlas for class 21.

Level 50 roads are 3 cells wide; level 51 are 2 cells wide; levels 52-53 are 1 cell wide.

(Level 50 represents interstate highways; 51 represents principal arterials; 52, minor arterials; 53, major urban collectors)

Source: Taxassessor-collector parcel data

Copied from EC90, augmented by TeleAtlas.

Roads are described as spaces between taxlot polygons within the tax-assessor-collector data sets ca. 1995; these polygons are gridded with the number of cells representing the roads dependent on the polygonal description.  This description is not available for cities in Yamhill and Columbia Counties because of the absence of digital tax-parcel data. Cells initially designated as class 7 - TM based commercial-industrial coincident with one cell gridded TeleAtlas roads were reclassed to 21 Minor roads.

Source: dot97c

Copied from EC90, augmented by TeleAtlas.

Features in this layer are 1 cell wide. In the absence of taxlot data for Yamhill and Columbia counties, an alternate means is needed to represent the local roads within their UGBs. Comparison of dot97c igds-level 12 with the Eugene-Springfield taxlot data shows a good alignment with the taxlot right-of-ways that are roads. Thus, by using these ODOT data, we are confident that the treatment of roads in Yamhill and Columbia Co. UGBs will be consistent with those UGBs for which we do have taxlots and from which we obtain roads directly. Cells initially designated as class 7 - TM based commercial-industrial coincident with one cell gridded TeleAtlas roads were reclassed to 21 Minor roads.

Source: dot97c

Copied from EC90.

This is gridded 1 cell wide.  When railroads and roads run side-by-side, and in close proximity, the gridded representations often overlay.  The railroad layer was selected to lie "beneath" the roads grids so that the roads representation would be continuous.  This means that the gridded railroad lines may disappear beneath the gridded roads in places.

Source:
TM landcover data/DO and Willamette River active channel 2000

This was extracted from the TM imagery so that features defined as "built" within the Willamette River would correctly be represented as defined by OSU coverage ac2kv3).    It is assumed that most of the occurrences in this category are gravel or channel bars, with some revetments, river-side roads, and, in the METRO area, bridges and piers.

Source:
Willamette River active channel 2000;

2000 TM interpretaion;

Stream orders 5-7 from rivreach_2

The representation of water is constructed from three components, which, in decreasing spatial precedence are: 1) For the Willamette River mainstem and major tributary confluence zones, the ac2kv3 polygon coverage was used to ensure that the channels would be delineated adequately; 2) water identified in the 2000 TM imagery; 3) vector Strahler stream orders 5-7 gridded from rivreach_2 at one cell width.

Source for EC90: full pixel search

Source for LULC2K: USGS Digital Orthophoto Quadrangle aerial phtographs (http://terraserver.microsoft.com/)

For EC90: [extracted from digital images of USGS 7.5 min. quadrangle maps]

These structures represent rural dwellings and other rural structures, derived from digital scanned images of USGS 7.5 min. quadrangle maps by automated processes and manually revised.

Note that some of the structures found via feature extraction from images fall beneath the roads, railroads and water features defined by the layers described above.  This occurs as the assembly process implements the precedence of themes rules. 

For LULC2K: [extracted from ca. 2000 USGS DOQs]

Structures were identified by brightness differences in the DOQ images lying in taxlot parcels which did not contain a structure in the EC90 map, and do have a ca. 2000 real market improvement value >= $15,000.

LULC2K: intermediate grids were produced for each DOQ.

Source:
TM landcover data/DO

This was separately extracted from the landcover so that it would overlay the urban landuse data obtained from ca. 2000 taxlot information (see below).

Source: taxlots

This grid contains the landcover for all parcels defined as civic and open space within the WRB, areas that are off-limits to urban and rural development. 

These data include the following categories: public schools, buildings, colleges/universities, Federal, state, county and local parks, wildlife refuges, reservations, public and private cemeteries, Nature Conservancy reserves.   Within UGBs, the "built"TM classes are mapped as "urban built unknown" (legend 11); outside the UGBs, the "built" categories are mapped as "rural built unknown" (legend 24) unless they lie within the Willamette River active channel; the rest of the landcover within the civic/os area remains as defined by the amalgamation of the other landcover data (as layered below).

This layer will have areas that coincide with taxlot defined areas (see "urban land use" below): this grid overrides those definitions. For example, in the taxlot definition, schools are defined as commercial; if these are public schools, civic/os redefines them to whatever the amalgamated landcover depicts. Thus, a school with a building and areas of playing fields will appear partly as "urban non-vegetated unknown" (11) and partly grass or forest etc. 

Source:
Taxlot coverages, and household density derived from the 2000 Federal Census.

For all counties except Columbia, the property class category of the tax assessor parcel data was remapped into residential, commercial, industrial and vacant. The residential parcels were then compared with the US census household density description to convert them to the appropriate hh density. Vacant lands were set to "nodata" so that the underlying landuses would "show through". Also, where parcels have undefined or ambiguous land uses or for land where no parcels are defined, the underlying landuses "show through".

Source:
TM landcover data/DO and  household density  derived from U.S. census

Inside UGBs: built high density landcover was remapped to commercial/industrial = 7; built low and med densities were remapped to Urban non-vegetated unknown (11), except in Columbia County wherein they are remapped to residential. This remapping is also used to represent the landcover built categories that fall within undefined or ambiguous parcels in UGBs with taxlot data (as described above).

Outside UGBs: "built" landcover is mapped as "rural non-vegetated unknown" (24). The landcover built density categories may include fallow land, rock, bare ground, gravel pits, gravel bars, roofs, roads, etc. Here, it is assumed that the rural structure data, the ODOT roads, etc. (as described above) are better descriptors of the land uses we wish to identify. Everything that is then left over after these land uses blot out the landcover "built" is set to "rural non-vegetated unknown". Note that gravel pits and mines will most likely be in this category (except for any that fall inside the mainstem Willamette River coverage, as described above). 

Cells initially designated as class 7 that were coincident with one cell gridded TeleAtlas roads were reclassed to 21 Minor roads.

Source: 
Patricia Berger, Bioresources Engineering, OSU

Agricultural crops are identified and their fields delineated by examination on a computer display of DOQ images within agriculturally identified taxlot parcels. Other ancillary data such as county agricultural census statistics are also used.

Source: 
Patricia Berger, Bioresources Engineering, OSU; TM landcover/DO;

(Michael Lefsky, Forest Sciences Laboratory, Oregon State University)

These data represent vegetation in areas not edited for agricultural land uses. Forest classes, natural shrub, and flooded marsh pixels are classified for most areas of the ecoregion. Areas not edited in this fashion receive their classes from the "Landcover TM' layer below.

TM landcover/DO

Source: 
TM landcover data/DO

Remote-sensed landcover from TM data with classes renumbered to match the master LULC legend.