Control Points for Landsat 7 Imagery, Canada (CPLIC) consist of a set of georeferenced points that are readily identifiable at various map scales. Along with the Landsat 7 orthoimages, they comprise one of the two components of the GeoBase Data Alignment Layer (GDAL).
The control data come from different sources; selection priority is given to the most accurate sources. The normal ranking in decreasing order is: Updated Road Network (URN) vector data, provincial vector data, accurate National Topographic Data Base (NTDB) data, federal aerotriangulation data, and other sources. Accuracy is assessed for each control point. The control data, which have been extracted from the sources indicated above, can be comprised of vector data from road intersections or centres of gravity of lakes and islands. In some cases, the centre line of a river represented as a surface may have been used.
Each control point is unique and its position is determined to simultaneously cover the greatest possible number of Landsat 7 images (location in areas of image overlap). Control points are distributed homogeneously within the image depending on specific sectors. The sectors are located around the image perimeter, in the image's areas of lowest and highest elevation, as well as the areas in which adjacent images overlap.
A map context is also associated with each control point (control point context). The intersections of linear topographic features (road, railway, watercourse, etc.) and the perimeters of lakes and islands are extracted in order to facilitate identification of control points. The reference entities result from vectorization of perceptible topographic features extracted from Landsat 7 source images.
Control data are distributed as geographic coordinates. The product is available in these file formats: GML (Geography Markup Language) ASCII and SHAPE (ESRI-TM).
But:
The control points were used for the geometric correction of Landsat 7 satellite imagery. They can also be used to correct vector data and for simultaneously displaying data from several sources prepared at different scales or resolutions.
Période de temps du contenu:
Information sur la période de temps:
Plusieurs dates et temps:
Date de début:
1999-01-01
État:
Progrès:
Complete
Fréquence de mise à jour et d'actualisation:
None planned
Domaine spatial:
Coordonnées de délimitation:
Coordonnée de délimitation Ouest:
-141
Coordonnée de délimitation Est:
-52
Coordonnée de délimitation Nord:
83
Coordonnée de délimitation Sud:
41
Mots-clés:
Thème:
Thésaurus de mots-clés du thème:
GCMD
Mot-clé du thème:
Earth Science > Land Surface > Topography
Mot-clé du thème:
Earth Science > Spectral/Engineering
Thème:
Thésaurus de mots-clés du thème:
none
Mot-clé du thème:
Geometric Correction
Mot-clé du thème:
Imagery
Lieu:
Thésaurus de mots-clés de lieu:
GCMD
Mot-clé de lieu:
Global Regions > Mid-latitude
Mot-clé de lieu:
Global Regions > North America
Mot-clé de lieu:
Global Regions > Northern Hemisphere
Mot-clé de lieu:
Global Regions > Western Hemisphere
Lieu:
Thésaurus de mots-clés de lieu:
CEONET
Mot-clé de lieu:
Canada
Mot-clé de lieu:
Canada > Alberta
Mot-clé de lieu:
Canada > British Columbia
Mot-clé de lieu:
Canada > Manitoba
Mot-clé de lieu:
Canada > New Brunswick
Mot-clé de lieu:
Canada > Newfoundland And Labrador
Mot-clé de lieu:
Canada > Northwest Territories
Mot-clé de lieu:
Canada > Nova Scotia
Mot-clé de lieu:
Canada > Nunavut
Mot-clé de lieu:
Canada > Ontario
Mot-clé de lieu:
Canada > Prince Edward Island
Mot-clé de lieu:
Canada > Quebec
Mot-clé de lieu:
Canada > Saskatchewan
Mot-clé de lieu:
Canada > Yukon
Contraintes d'accès:
Users must register to access data
Contraintes d'utilisation:
Data are subject to the GeoBase Unrestricted Use Licence Agreement.
Point de Contact:
Information sur le contact:
Personne contact primaire:
Personne contact:
Customer Support Group
Organisation contact:
Government of Canada, Natural Resources Canada, Earth Sciences Sector, Geomatics Canada, Centre for Topographic Information
Adresse du contact:
Type d'adresse:
Mailing and physical address
Adresse:
2144, King Street West, Suite 010
Ville:
Sherbrooke
État ou province:
(Quebec)
Code postal:
J1J 2E8
Pays:
Canada
Numéro de téléphone du contact:
+01-819-564-4857 / 1-800-661-2638 (Canada and USA)
All the valid control points are available. For every control point, a control point context (reference geometry) is produced for each Landsat 7 source image which is orthorectified by the Centre for Topographic Information in Sherbrooke. One of the contexts available for each control point is distributed and is randomly selected.
Précision d'alignement:
Précision d'alignement horizontal:
Rapport sur la précision d'alignement horizontal:
Control Point: The position of the control point is extracted from the most accurate data source available when the point is created. The planimetric accuracy of the source data is identified as an attribute for each entity occurrence. A certain number of data sources have been used to create the control points: provincial vector data, roads from the Updated Road Network (URN), National Topographic Data Base (NTDB) data, and geometrically rectified aerial photos (orthophotos). Control Point Context: The planimetric accuracy of the control point context's geometry cannot be determined. It consists of an entity produced solely for visual reference.
Précision d'alignement vertical:
Rapport sur la précision d'alignement vertical:
Control Point: The control point elevation (height) is extracted from available digital elevation models (DEM): provincial DEMs and Canadian Digital Elevation Data (CDED) at the 1:50 000 and 1:250 000 scales. The value of the source data's altimetric accuracy is attributed to the control point.