The Connecticut 1980 Coastal Photography Tile Index is a polygon feature class that defines the approximate extent of the geographic area covered by each Connecticut 1980 Coastal Photography image. The 1980 Coastal Photography data for Connecticut is comprised of 777 non-georeferenced 1:12,000 scale 9" by 9" vertical color infrared aerial images and these data include a polygon feature for each image that measures roughly 1.7 by 1.7 miles and covers approximately 2.89 square miles. The extent of all the polygons comprise a project area described by: * all land areas within one-thousand (1000) feet of Mean High Water (MHW) and within one-thousand (1000) feet of state-regulated tidal wetlands; * an area of at least two-thousand (2000) feet waterward of the immediate shoreline of Long Island Sound; * all offshore islands within the territorial borders of the State of Connecticut including Goose Island and Falkner Island (offshore of Branford); Calf Islands and Great Captain Island (offshore of Greenwich); Norwalk Islands (offshore of Norwalk); Thimble Islands (offshore of Branford); Sandy Point (offshore of Stonington); and all islands in the Connecticut part of Fishers Island Sound; and * the main stem of the Connecticut River up to the Massachusetts State line. The Connecticut 1980 Coastal Photography Tile Index is organized in a non-regular grid pattern that reflects the orientation of the flight lines needed to accurately and efficiently photograph the project area. The tiles have an approximate sidelap (overlap between tiles in adjacent flightlines) of 30% and an approximate endlap (overlap between adjacent tiles within a flightline) of 60% in order to achieve well defined stereo pairs. Each point feature is identified by a unique PHOTO_NO value, which matches the filename of the corresponding digital photo image as well as the hardcopy prints and transparencies maintined by the State of Connecticut Department of Environmantal Protection. In addition, each polygon feature also contains the unique flight line, film roll, photo exposure numbers, and date recorded on the original film transparency and hardcopy print as well as basic information on the flight including the year, photography type, tide control, vegetation state, scale, etc. NOTE: Due to problems in conforming to several contractual flight specifications for all images (namely coverage area, low-tide coordination, solar orientation, cloud coverage, and flight metrics,) this project was reflown in the Summer of 1981.
The Connecticut 1980 Coastal Photography is neither orthorectified nor georeferenced to any real-world coordinate sytem. To maximize the quality of the images and their contents, photography was specified to conform to the following environmental conditions: * photos were only taken during times of no/minimal cloud cover when lighting and weather conditions optimized the color infrared film; * solar altitude was more than thirty (30) degrees; * the ground detail was not obscured by flooding; * the foliage (salt marsh vegetation in particular) was fully developed; * seasonal conditions (summer) favored maximum human use/recreation activities (e.g., boats & temporary docks/structures in water, etc.); * photo times were planned within one (1) hour window before or after a predicted low tide based on National Oceanic & Atmospheric Administration (NOAA) predicted tide tables. (In instances where this window caused conflicts with the general restricted hours, tide coordination times superceded that limitation); and * no photography was flown between the hours 1100 and 1300 Eastern Standard Time (EST) to minimize specular reflection. NOTE: Due to problems in conforming to several contractual flight specifications for all images (namely coverage area, low-tide coordination, solar orientation, cloud coverage, and flight metrics,) this project was reflown in the Summer of 1981. The photos exist as 1:12,000 vertical color infrared images. Color infrared photography, often called false color photography because it renders the scene in other than the normal colors seen by the human eye, is widely used for interpretation of natural resources. Atmospheric haze does not interfere with the acquisition of the image, therefore is well suited to aerial photography. Because the film is high speed and subject to degrees of degradation in handling before exposure, the aerial photographs can vary in overall tone. This variability can complicate the interpretation of color tones between photographs, but some general guidelines can be given to aid the inexperienced interpreter. * The red tone of color infrared aerial photographs is almost always associated with live vegetation. Very intense reds indicate vegetation which is growing vigorously and is quite dense. Knowledge of the vigor and density of vegetation is important to the interpretation of the red colors on color infrared aerial photography. * As the vigor and density of vegetation decreases, the tones may change to light reds and pinks. If plant density becomes low enough the faint reds may be overcome by the tones of the soils on which the plants are growing. The ground areas in this case will appear in shades of white, blue, or green depending on the kind of soil and its moisture content. As plant vigor decreases, the vegetation will show as lighter shades of red and pink, various shades of greens, and possible tans. Dead vegetation will often be shades of greens or tans. * Bare soils will appear as shades of white, blue, or green in most agricultural regions. In general, the more moist the soil the darker the shade of that particular soil color. Composition of the soil will affect the color tones shown on the photographs. Dry sand will appear white and, with more moisture, may be very light gray or possibly light tan. Clayey soils will generally be darker in color than sands and tend toward tans and bluegreens. Again, wetter clays will be darker shades of the same tones. Soils high in organic matter, like silts and loams will be even darker in color, and usually in shades of blues and greens. Wet organic soils can be very dark blue or green in the aerial photographs. * Man-made features will show in the tones that relate to the materials they are made of. Asphalt roads, for example, will be dark blue or black, gravel or dirt roads will show as lighter colors, depending on the soil materials involved in their composition, and concrete roads will appear light in tone, assuming clean concrete. The buildings and streets of towns can be considered in a similar manner, their color dependent on the material they are made of. * Water will appear as shades of blue, varying from nearly black to very pale blue. Clear, clean water will appear nearly black. As the amount of sediment increases, the color becomes increasingly lighter blue. Very shallow water will often appear as the material present in the bottom of the stream. For example, a very shallow stream with a sandy bottom will appear white due to the high level of reflection of the sand. * Degraded film will result in photographs which have an overall blue or green cast. When that occurs, the interpretation must consider what that overall cast will do to a "normal" rendition of the scene. (Description and guidelines for color infrared photography taken from the United States Geological Survey Aerial Photo FAQ web page, http://edc.usgs.gov/guides/news/aerialfaq.htmlt#A10)
date of photography
Connecticut 1980 Coastal Photography Tile Index represented as polygon features. (Source: State of Connecticut, Department of Environmental Protection)
Image File Name (Source: State of Connecticut, Department of Environmental Protection)
Feature geometry. (Source: ESRI)
Internal feature number. (Source: ESRI)
Feature geometry. (Source: ESRI)
Text field indicating the year the photos were taken in. (Source: State of Connecticut, Department of Environmental Protection)
Numeric field providing a unique identifier for each tile. Idenitical value to PHOTO_NO. (Source: State of Connecticut, Department of Environmental Protection)
Text field providing a unique identifier for each tile. Idenitical value to ID_NO. (Source: State of Connecticut, Department of Environmental Protection)
| Range of values | |
|---|---|
| Minimum: | 1 |
| Maximum: | 777 |
Identifies which roll of film was used for the photo(s.) (Source: State of Connecticut, Department of Environmental Protection)
| Range of values | |
|---|---|
| Minimum: | 1 |
| Maximum: | 7 |
Identifies which flight line was associated with the photo(s.) (Source: State of Connecticut, Department of Environmental Protection)
| Range of values | |
|---|---|
| Minimum: | 1 |
| Maximum: | 47 |
Identifies the specific date a photo was taken. (Source: State of Connecticut, Department of Environmental Protection)
Identifies the time a photo was taken, iff applicable. Time values were only recorded for the first and last photos in a flightline. (Source: State of Connecticut, Department of Environmental Protection)
Scale of the photos. (Source: State of Connecticut, Department of Environmental Protection)
Type of film used to capture the photos. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| Color Infrared | [not provided] |
| Black/White | [not provided] |
| True Color | [not provided] |
| Other | [not provided] |
Identifies the type of photo by classifying the camera orientation. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| Scanned Vertical Aerial Film | scanned version of aerial photo - no georeferencing/orthorectification |
| Digital Orthophoto | orthorectified digital photo |
Indicates if tide control was used an in what manner. (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| No - outside of specifications | The photos do not conform to project specifications for this attribute. |
| The photos do not conform to project specifications for this attribute. | The photos do not conform to project specifications for this attribute. |
Identifies during what state deciduous vegatation was in when the photography (Source: State of Connecticut, Department of Environmental Protection)
| Value | Definition |
|---|---|
| Leaf on | taken during leaf on conditions |
| Leaf off | taken during leaf off conditions |
DPI (Dots Per Inch) of the digital scans of the original film transparencies. (Source: State of Connecticut, Department of Environmental Protection)
Calculation relating the scale of the photography to the DPI of the scanned imagery to provide a ground measurement, in feet, for each pixel. Defined by [photo scale/image DPI/12] (Source: State of Connecticut, Department of Environmental Protection)
Entity responsible for compiling the original data. (Source: State of Connecticut, Department of Environmental Protection)
Entity responsible for maintaining the current data. (Source: State of Connecticut, Department of Environmental Protection)
Information encoded about the tile area polygon features includes the name of the corresponding photo image (PHOTO_NO), the aerial flight data (FLTLINE_NO, ROLL_NO, PHOTODATE, PHOTOTIME, PHOTOSCALE, etc.) AND project data (PHOTO_YR, VEGETATION, TIDE_CNTRL, etc.)
not applicable
Aero Graphics Corp. was contracted by the State of Connecticut to provide the Connecticut 1980 Coastal Photography. All imagery and data products were defined under State of Connecticut contract award number 790-A-5-2634.
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These data serve as a polygon index to the set of 1980 Coastal Photography image tiles for Connecticut.
Baemap reference to identify and align 1980 photo images.
A previously created point based layer used to identify the approximate location for the 1980 Coastal Photography Tile Index features on maps or with other GIS data layers.
The scanned imagery of the 1980 Coastal Photography flight films used to create and orient the corresponding image tile index feature.
Photo_index_1980Coastal_tile is in GeoDatabase Feature Class format
Georeferencing followed by Feature digitizing, placement, and attribution (heads up digitizing method) - Using ESRI ArcGIS software, the coordinate system for an ArcMap data frame was set to the Connecticut State Plane Coordinate System NAD 83, with map units in feet. As a reference layer, Source 1, (Connecticut 2004 Orthophoto Basemap) was added to the data frame. The map scale for the reference layer is 1:12,000, making it the most accurate reference layer available at the time of georeferencing. A representative photo from Source 3, (Connecticut 1980 Coastal Imagery) was then added to the data frame and manually georeferenced by adding 3 to 4 control points that linked known positions on the data source to known positions (in map coordinates) on the reference layer (Connecticut 2004 Orthophoto Basemap). Control points were added by first clicking a known location on the source map (e.g. road intersection) and then clicking on the same location on the reference layer (Connecticut 2004 Orthophoto Basemap). The selection of control points is a subjective process that greatly affects the transformation process. The Root Mean Square (RMS) error generated by the ArcGIS software indicated the amount of error involved in transforming the control point coordinates and quality of the georeferencing process. Efforts to keep the overall RMS error to a minimum were employed, typically involving selecting different control point locations to georeference the source data when bad feature fit or systematic shifts indicated by poor transformation were observed. RMS error values were not retained. Transformations involved first order polynomial operations only. With a correctly georeferenced data source, the orientation and extent of the representative photo from Source 3, (Connecticut 1980 Coastal Imagery) was hand-digitized in the Source 4, (Connecticut 1980 Coastal Photography Tile Index) geodatabase polygon feature class by zooming into the corners place vertices that would to as accurately as possible replicate the geometry of the georeferenced image as a polygon. This representative polygon tile was then copied, placed, and oriented for the other 776 1980 photo locations described in Source 2 (Connecticut 1980 Coastal Photography Index Points.) Approximate placements for the tiles were driven by the index point locations, and visual inspections of the features found on the 1980 photo and the 2004 orthophoto basemap led to refining the tile placement by rotating or shifting it to best fit the visual content and extent of the two images. Once a polygon tile was correctly placed, features unique to that tile (i.e., flight line, film roll, exposure number, photo number, date, time) were assigned. Feature location and attribute accuracy was visually checked and inspected by symbolizing and labeling features according to attribute value on the computer screen. Inconsistencies or anomolies were examined and corrected if necessary. Once all polygons were placed, attributes germane to the entire flight were added (i.e., photo year, tide control status, scale, ground resolution, data compiler/maintainer, etc.) via automated field calculations. Feature location and attibute accuracy was once again visually checked and inspected by symbolizing and labeling features according to attribute value on the computer screen. Inconsistencies or anomolies were examined and corrected if necessary.
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Dataset copied.
The Connecticut 1980 Coastal Photography Tile Index layer retains the feature types and information identified by the State of Connecticut, Department of Environmental Protection and obtained from the flight specifcations . All attributes have valid values. Values are within defined domains. The Connecticut 1980 Coastal Photography Tile Index features were manually and automatically selected and populated with attributes values to (uniquely) identify and describe individual features. Accuracy checks involved visually inspecting the correlation between the Connecticut 1980 Coastal Photography Tile Index polygon features and their corresponding photographs with 2004 orthophoto basemap imagery for the State of Connecticut to ensure the non-georeferenced photos were located and oriented to the ground features.
The horizontal positional accuracy of this data is unknown. Polygon features are approximate (alternate) representations for large area objects or observations having well-defined, visible, recoverable, or permanent boundaries or demarcations. Polyogn features are accurately positioned for these locations because objects were easily identifiable on aerial photos.
The completeness of the data reflects the content of the data source, which is the State of Connecticut Department of Environmental Protection 1980 Coastal Photography. The Connecticut 1980 Coastal Photography Tile Index is complete in the sense that it accurately reflects the number, extent, and location of the photos available at the time the State of Connecticut, Department of Environmental Protection created the layer. This data is not updated.
Polygon features conform to the following topological rules. Polygons are single part. There are no duplicate polygons. Polygons do not self overlap, although adjacent polygons do overlap. Overlap was defined by flight specifications and corresponds to approximately 30% sidelap (overlap between tiles in adjacent flightlines) and 60% endlap (overlap between adjacent tiles within a flightline.) Establishment of logical consistency was performed by the State of Connecticut, Department of Environmental Protection using ESRI ArcGIS software to manually create and control feature topology in GEODATABASE format. No automated procedures or tests were performed to guarantee desired topology other than visual inspection.
None. No restrictions or legal prerequisites for using the data after access is granted. The data is suitable for use at appropriate scale, and is not intended for maps printed at scales greater or more detailed than 1:12,000 scale (1 inch = 1,000 feet). Although this data set has been used by the State of Connecticut, Department of Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Environmental Protection as to the accuracy of the data and or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the State of Connecticut, Department of Environmental Protection in the use of these data or related materials. The user assumes the entire risk related to the use of these data. Once the data is distributed to the user, modifications made to the data by the user should be noted in the metadata. When printing this data on a map or using it in a software application, analysis, or report, please acknowledge the State of Connecticut, Department of Environmental Protection as the source for this information.
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Although this data set has been used by the State of Connecticut, Department of Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Environmental Protection as to the accuracy of the data and or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the State of Connecticut, Department of Environmental Protection in the use of these data or related materials. The user assumes the entire risk related to the use of these data. Once the data is distributed to the user, modifications made to the data by the user should be noted in the metadata.
| Data format: | in format Shapefile, Feature Class (version ArcGIS) |
|---|---|
| Network links: | http://www.ct.gov/deep |
The data distributor does not provide custom GIS analysis or mapping services. Data is available in a standard format and may be converted to other formats, projections, coordinate systems, or selected for specific geographic regions by the party receiving the data.
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