Point Type Number of Points Sanborn Supplied Field Sites 315 State of Maine Supplied Field Sites 190 Sanborn Photointerpreted Sites 390 State of Maine Photointerpreted Sites 722
Photointerpreted Site Total 1112 Field Site Total 505 Accuracy Site Total 1617
Initially, approximately 1500 reference data sample points were selected at random in order to assist the State of Maine field crews in selecting field sites and destination planning. Field sites were visited by the State of Maine field crews in the late summer of 2005. Both photointerpreted and field sites were checked to ensure that each represented a homogenous feature on the SPOT imagery so that the points conformed to the MeLCD MMU requirements. The minimum mapping unit (MMU) used for the Accuracy Assessment refers to the requirement that an Accuracy Assessment point must fall in the center of a 0.89 acre area that consists of one and only one cover type. If these criteria are not met it will result in confusion/error caused by positional/spatial accuracy of the map rather than the thematic accuracy of the map.
Fuzzy interpretations were made and added to the database when warranted and agreed to by the State of Maine, i.e. when the interpretations from the DOQQs were ambiguous. 15% of the interpretations, or 237 out of 1617. If any of the fuzzy accuracy assessment calls matched the map, then that sample would be considered a positive match. This fuzzy accuracy assessment methodology is represented in the error matrices shown in this report.
A digital orthophoto can be incorporated into any geographic information system (GIS) that can manipulate raster images. It can function as a cartographic base for displaying, generating, and modifying associated digital planimetric data. Other applications include vegetation and timber management, routing and habitat analysis, environmental impact assessments, emergency evacuation planning, flood analysis, soil erosion assessment, facility management, and groundwater and watershed analysis. The accuracy and extraordinary detail provided by the digital orthophoto allow users to evaluate their data for accuracy and completeness, make real-time modifications to their data, and even generate new files.
DOQQ is a mosaic of digital orthophoto quarter quadrangles stored in a Maine Office of Geographic Information Systems (MEGIS) Oracle/ArcSDE environment. The digital orthophoto quarter quadrangles that form the mosaic are available for download from the Maine GIS Internet Data Catalog in compressed MrSID format in 7.5 minute quadrangle map extent. Compression with LizardTech's MrSID software creates two files a .sid image and an .sdw file georeferencing file, approximate size of the download is 12MB, one sixteenth of the uncompressed DOQQ image.
Image analysis techniques used in production of the map were a combination of supervised classification using Classification and Regression Tree (CART) algorithms and spatial modeling. The use of three Landsat image dates provided the ability to discriminate specific elements of the landscape. For example; the spring imagery was useful for the classification of wetlands and the separation of conifers and broadleaf species and the fall imagery was useful for the discrimination of broadleaf species. After the creation of the NOAA C-CAP base map, Sanborn used image segmentation to refine the spatial boundaries of the land cover classes, using a merge of the Landsat leaf on imagery and the SPOT 5 imagery. The segments produced by this process were labeled using automated methods to build the final Maine land cover dataset (MeLCD). After the completion of the classification, the map was extensively reviewed by Sanborn analysts and specific classes were modeled and edited by hand to remove class confusion.
Characteristic land cover features: Large commercial/industrial complexes and associated parking, commercial strip development, large barns, hangars, interstate highways, and runways.
Characteristic land cover features: Small buildings such as single family housing units, farm outbuildings, and large sheds.
Characteristic land cover features: Same as Medium Intensity Developed with the addition of streets and roads with associated trees and grasses. If roads or portions of roads are present in the imagery they are represented as this class in the final land cover product.
Characteristic land cover features: Parks, lawns, athletic fields, golf courses, and natural grasses occurring around airports and industrial sites.
Characteristic land cover features: Crops (corn, soybeans, vegetables, tobacco, and cotton), orchards, nurseries, and vineyards.
Characteristic land cover features: Crops such as alfalfa, hay, and winter wheat.
Characteristic land cover features: Prairies, meadows, fallow fields, clear-cuts with natural grasses, and undeveloped lands with naturally occurring grasses.
Characteristic species: Maples (Acer), Hickory (Carya), Oaks (Quercus), and Aspen (Populus tremuloides).
Characteristic species: Longleaf pine (Pinus palustris), slash pine (Pinus ellioti), shortleaf pine (Pinus echinta), loblolly pine (Pinus taeda), and other southern yellow (Picea); various spruces and balsam fir (Abies balsamea); white pine (Pinus strobus), red pine (Pinus resinosa), and jack pine (Pinus banksiana); hemlock (Tsuga canadensis); and such western species as Douglas-fir (Pseudotsuga menziesii), redwood (Sequoia sempervirens), ponderosa pine (Pinus monticola), Sitka spruce (Picea sitchensis), Engelmann spruce (Picea engelmanni), western red cedar (Thuja plicata), and western hemlock (Tsuga heterophylla).
Characteristic species: Those listed in 9 and 10 as well as chaparral species such as chamise (Adenostoma fasciculatum), chaparral honeysuckle (Lonicera interrupta), scrub oak (Quercus beberidifolia), sagebrush (artemisia tridentate), and manzanita (Arctostaphylos spp.).
Characteristic species: Tupelo (Nyssa), Cottonwoods (Populus deltoids), Bald Cypress (Taxodium distichum), American elm (Ulmus Americana), Ash (Fraxinus), and tamarack.
Palustrine Emergent Wetland-Characteristic species: Cattails (Typha spp.), sedges (Carex spp.), bulrushes (Scirpus spp.), rushes (Juncus spp.), saw grass (Cladium jamaicaense), and reed (Phragmites australis).
Estuarine Scrub-Shrub Wetland-Characteristic species: Sea-myrtle (Baccharis halimifolia) and marsh elder (Iva frutescens).
Estuarine Emergent Wetland-Characteristic species: Cordgrass (Spartina spp.), needlerush (Juncus roemerianus), narrow leaved cattail ( Typha angustifolia), southern wild rice (Zizaniopsis miliacea), common pickleweed (Salicornia virginica), sea blite (Suaeda californica), and arrow grass (Triglochin martimum).
Characteristic land cover features: Beaches, bars, and flats.
Characteristic land cover features: Quarries, strip mines, gravel pits, dunes, beaches above the high-water line, sandy areas other than beaches, deserts and arid riverbeds, and exposed rock.
Characteristic land cover features: Lakes, rivers, reservoirs, streams, ponds, and ocean.
Characterization conditional: Forest loss must have occurred after 1995.
Characterization conditional: Forest loss must have occurred after 1995.
Characterization conditional: Forest loss must have occurred after 1995.
Characterization conditional: Forest loss and subsequent re-growth must have occurred after 1995.