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Process Description: AZ’s current contractor IHS, Premier Data Services, took AZ’s GCDB’s data and made it CadNSDI and parcel fabric. Previous Steps pre-IHS PLSS Intersected: BLM Cadastral Survey using the computational programs of either GMM or PCCS has generated the data where BLM Cadastral is the identified data steward. For both programs the first step is to compile survey input data from the best and most current survey records. Control points are identified, evaluated and entered into a control database. With GMM the survey data, measurements abstracted from survey plats, and control stations extracted from the control database are manually entered with weighting factors into GMM software. Compass rule and least squares adjustments are performed using weighting factors assigned to both control stations and survey line data, based on survey methodologies and vintage of survey. With GMM, section subdivision is performed to achieve land unit detail to at least the forty acre (1/16th) level. Instructions for calculating non-‐regular and minor subdivisions are persistently stored during collection and rerun after every new adjustment in order to achieve the detail necessary to delineate all lines required for depicting federal rights, interests, restrictions, and encumbrances. Coincident lines and lines identified as non-‐boundary lines are removed from the data set used for final land unit constructions. Line intersections are computed and given unique identifiers and land units are constructed. GMM lists all coordinates produced by the compass rule and least squares adjustments and subdivision, with connectivity codes between points and compiles them into a single file for development of Geographic Information Systems (GIS) output. With PCCS the survey data, measurements abstracted from survey plats, and control stations extracted from the control database are manually entered into the PCCS processing software. A succession of compass rule adjustments is performed on the lines to adjust them to the control points, followed by a least squares analysis. The resulting coordinates are accompanied by indications of positional reliability; the average of misclosures in the data set and the maximum misclosure in the data set. PCCS lists all coordinates produced by the compass rule and least squares adjustments with connectivity codes between points and compiles them into a single file for development of Geographic Information Systems (GIS) output. With PCCS, section subdivision is performed to achieve land unit detail to at least the forty-acre (1/16th) level. Separate Process Step: GCDB data conversion software (also called data prep) verifies correctness of GCDB file formats and content based on the polygon coding and the rules associated with those codes. Verified coordinate, line and label files are converted to GIS coverages using the topology check application. All errors in topology are flagged for editing and correction. If topological errors exist, editing of arc and node data, as well as parcel labels, is performed using either GMM or ArcGIS Interface. Final edits are entered into input files and the process is repeated until all errors are corrected and a successful GIS coverage is created. GIS coverages are edge matched with adjoining township data sets to insure a seamless PLSS data set is created. Topologically correct GIS coverages are modified to use FGDC compliant naming conventions and then loaded into the CADNSDI. Separate Process Step: The resulting GCDB data sets are imported into a file geodatabase feature class called LADESC and the points are loaded into the PLSSCorners feature class. A series of extract-‐transfer-‐load (ETL) routines are run to import the data into the PLSS Intersected feature class. Metadata is loaded and edited. Other Feature Classes (except PLSS Points): This feature class is built from the PLSSIntersected feature through a series of SQL selects, dissolves and geoprocessing. The selection uses only the current PLS data so any polygon labeled with a survey note of R (replaced) will not be used in building derived feature classes. Polygons are combined based on the attributes and rules of combination. PLSS Points: For points with a BLM Cadastral as the data steward this feature class is built geographic coordinate database (GCDB) point files. All PLSS Points are at the nodes of line intersections and have a unique identifier as well as any applicable alias that represents the point identifier in adjoining townships or adjoining features. For points with county or state data stewards the PLSS corners are imported from geodatabase files provided by the data steward. Attribute_Accuracy_Report - The BLM GCDB personnel using software tools such as dataprep and native GS tools in ArcGIS checked the data for attribute accuracy by verifying it against land records databases such as legal land description (LLD) and Case Status databases. There may be instances where information in survey records and LLD and Case do not agree or places where records are missing. If there are questions about the attribution of a polygon contact the identified data steward. Horizontal_(Vertical) Positional_Accuracy_Report - For PLSSPoints: Accuracy of the individual points contained in the PLSSPoint Feature Class that were determined using GMM software the resulting accuracy is reported with the point in the feature class. An overall statement of reliability may be provided for points that are derived from the least accurate component of the error ellipse. Accuracy of the individual points that were determined using PCCS software a carries positional reliability factor for the average of the misclosures in the data set and the maximum misclosure in the data set. For Polygon Feature Classes: The polygon lines are built from the PLSS Points. The PLSS points should be at the nodes of the lines. The horizontal accuracy of the polygon lines is derived from the accuracy of the points at the nodes.
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Process Date: unknown
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Process Contact:
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Contact Information:
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Contact Organization Primary:
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Contact Organization: Premier Data Services S&P Global
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Contact Person: Account Manager Premier Data Services S&P Global
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Contact Position: Account Manager
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Contact Address:
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Address Type: mailing
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Address: 15 Inverness Way East
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City: Englewood
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State or Province: CO
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Postal Code: 80112
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Country: US
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Contact Voice Telephone: (303) 377-0033
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Contact Electronic Mail Address: @ihsmarkit.com