Geodetic coordinates within the State of California that are based on the North American Datum of 1983 and conforming to the provisions of this chapter shall be known as “California Geodetic Coordinates of 1983.”
Chapter 4California Geodetic Coordinates
Section § 8870
This law states that geodetic coordinates in California, which rely on the North American Datum of 1983 and meet specific guidelines, are officially referred to as 'California Geodetic Coordinates of 1983.'
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Section § 8871
This law section provides definitions for various terms used in the chapter related to geodetic and spatial references. It explains abbreviations such as NGS (National Geodetic Survey), CSRC (California Spatial Reference Center), NAD83 (North American Datum of 1983), GPS (Global Positioning System), FGDC (Federal Geographic Data Committee), FGCS (Federal Geodetic Control Subcommittee), CSRN (California Spatial Reference Network), and CGC83 (California Geodetic Coordinates of 1983).
As used in this chapter:
(a)CA Public Resources Code § 8871(a) “NGS” means National Geodetic Survey or its successor.
(b)CA Public Resources Code § 8871(b) “CSRC” means California Spatial Reference Center or its successor.
(c)CA Public Resources Code § 8871(c) “NAD83” means North American Datum of 1983.
(d)CA Public Resources Code § 8871(d) “GPS” means Global Positioning System and includes other, similar spaced-based systems.
(e)CA Public Resources Code § 8871(e) “FGDC” means the Federal Geographic Data Committee or its successor.
(f)CA Public Resources Code § 8871(f) “FGCS” means the Federal Geodetic Control Subcommittee or its successor.
(g)CA Public Resources Code § 8871(g) “CSRN” means California Spatial Reference Network as defined by Chapter 3 (commencing with Section 8850), “Geodetic Datums and the California Spatial Reference Network.”
(h)CA Public Resources Code § 8871(h) “CGC83” means California Geodetic Coordinates of 1983.
National Geodetic Survey California Spatial Reference Center North American Datum of 1983 Global Positioning System Federal Geographic Data Committee Federal Geodetic Control Subcommittee California Spatial Reference Network California Geodetic Coordinates of 1983 geodetic datums spatial reference systems space-based systems geodetic control mapping coordinates surveying standards data committee
Section § 8872
This law states that the term “California Geodetic Coordinates of 1983,” or its abbreviation like “CGC83,” should only refer to geodetic coordinates that are based on the North American Datum of 1983 (NAD83) and meet the guidelines of this specific chapter.
The phrase “California Geodetic Coordinates of 1983” or any abbreviation thereof, such as “CGC83,” shall be used only in reference to geodetic coordinates based on NAD83 and conforming to the provisions of this chapter.
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Section § 8873
This law specifies how geographic coordinates should be represented. They can be shown as either latitude and longitude, ellipsoid height, or as Cartesian coordinates (x, y, z). If Cartesian coordinates are used, they must follow the same symbols and conventions as those established by the National Geodetic Survey (NGS).
CGC83 values shall be expressed as latitude, longitude, or ellipsoid height values or as Cartesian coordinates (x, y, z). When Cartesian coordinates are used, the symbols and conventions utilized shall be the same as that used by NGS.
geographic coordinates latitude longitude ellipsoid height Cartesian coordinates x y z symbols conventions National Geodetic Survey NGS CGC83 values coordinate representation ellipsoid height values mapping standards geodetic systems
Section § 8874
In California, latitude and longitude values for CGC83 must be shown in degrees with minutes, seconds, and decimals, or as decimals of a degree. Heights measured on the ellipsoid should be in meters with decimals, or in feet with decimals, using the 'U.S. Survey Foot' standard. Cartesian coordinates must be in meters with decimals. Measurements must clearly state their units on any document they appear.
CGC83 latitude and longitude values shall be expressed in degrees, minutes, seconds, and decimals of a second, or degrees and decimals of a degree. CGC83 ellipsoid height values shall be expressed in meters and decimals of a meter or feet and decimals of a foot. When ellipsoid height values are expressed in feet, the “U.S. Survey Foot” (one foot equals 1200/3937 meters) shall be used as the standard foot. CGC83 Cartesian coordinate values shall be expressed in meters and decimals of a meter.
When CGC83 values are stated on any document, the unit of measure shall be clearly stated.
latitude and longitude CGC83 degrees minutes seconds decimal degrees ellipsoid height meters feet U.S. Survey Foot Cartesian coordinates unit of measure
Section § 8875
This law outlines requirements for surveys that establish CGC83 values. It states that surveys must be connected to a reference station, such as a CSRN station or specific geodetic control stations outside California. These stations must be documented or shown on official maps and adhere to accuracy standards. Additionally, if accuracy is claimed, it must meet standards published by FGDC or FGCS.
The survey that establishes a CGC83 value or values shall meet all of the following requirements:
(a)CA Public Resources Code § 8875(a) The survey shall be referenced to and shall have field-observed statistically independent connections to one or more appropriate reference stations that is one of the following:
(1)CA Public Resources Code § 8875(a)(1) CSRN station.
(2)CA Public Resources Code § 8875(a)(2) Geodetic control station located outside of the State of California that meets all the requirements for inclusion in the CSRN except that the station is outside California.
(3)CA Public Resources Code § 8875(a)(3) Existing CGC83 station that:
(A)CA Public Resources Code § 8875(a)(3)(A) Is shown on a map filed with the applicable county surveyor by a public officer, subdivision map, corner record, or record of survey.
(B)CA Public Resources Code § 8875(a)(3)(B) Meets all the requirements for inclusion in the CSRN except that the station and its data are not published by NGS or CSRC.
(C)CA Public Resources Code § 8875(a)(3)(C) Has an accuracy, conforming to the applicable CSRN requirements, stated for the station’s value.
(4)CA Public Resources Code § 8875(a)(4) Existing CGC83 station that is shown on a public map or document that:
(A)CA Public Resources Code § 8875(a)(4)(A) Is compiled and maintained by the applicable county surveyor.
(B)CA Public Resources Code § 8875(a)(4)(B) Meets all the requirements for inclusion in the CSRN except that the station and its data are not published by NGS or CSRC.
(C)CA Public Resources Code § 8875(a)(4)(C) Has an accuracy, conforming to the applicable CSRN requirements, stated for the station’s value.
(b)CA Public Resources Code § 8875(b) If an accuracy is to be claimed for the CGC83 value or values established, the claimed accuracy shall be an accuracy standard published by FGDC or FGCS.
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Section § 8876
If you're claiming a specific CGC83 value's accuracy in a survey, you must document it in a detailed manner. The documentation should include several key elements:
(a) For each CGC83 station, list the final CGC83 values.
(b) Provide the specific date in decimal format that the values are based on, ensuring it's consistent with a recognized epoch by NGS or CSRC. Adjust any differing horizontal positions of controlling stations to match the consistent epoch.
(c) Declare the accuracy standard used, whether it's local or network accuracy, according to FGDC or FGCS standards.
(d) Include extra data backing up the accuracy claim, covering equipment used, a control diagram, methods, software, and any other relevant details for evaluating the survey's validity.
If an accuracy is claimed for a CGC83 value or values, the survey that established the value or values shall be documented on a map, record of survey, corner record, or other document that includes, at a minimum, the following:
(a)CA Public Resources Code § 8876(a) For each CGC83 station, the resultant CGC83 value or values.
(b)CA Public Resources Code § 8876(b) The epoch (date), in a decimal year format to two decimal places, that is the basis of the CGC83 values shown. The epoch shall be the published NGS or CSRC epoch of a controlling station for the survey.
If the published epochs for the horizontal positions of the controlling stations are not the same, appropriate adjustments shall be made to the horizontal values of the controlling stations so that said values of all the controlling stations are at one consistent epoch published by NGS or CSRC. These adjustments in the coordinates of the controlling stations shall be made in accordance with procedures and values published by NGS or CSRC.
(c)CA Public Resources Code § 8876(c) The FGDC and FGCS accuracy standard of the CGC83 value or values established. FGDC accuracies shall be identified as either a local or network accuracy.
(d)CA Public Resources Code § 8876(d) Additional written data that justifies the FGDC or FGCS accuracy standard shown. Such additional written data shall include observation equipment, control diagram including required field-observed statistically independent connection or connections, adjustment methodology and software used, a summary of the procedures used or a reference to published commonly accepted procedural specifications, final residuals or closures, and other data essential for others to evaluate the survey.
CGC83 value documentation survey accuracy map documentation record of survey corner record epoch date NGS epoch CSRC epoch horizontal position adjustment FGDC standard FGCS accuracy standard local accuracy network accuracy survey methodology observation equipment
Section § 8877
This law section requires that any document showing CGC83 geodetic coordinate values (like a map or land survey) must include certain details. It must state that the values are CGC83 values and note any exceptions. The document should also mention the specific station(s) these values are connected to, including the reference station's geodetic coordinate values and their accuracy. Additionally, the document needs to specify the 'epoch' or time reference of the CGC83 values, complying with a related legal provision.
When a CGC83 value or values are shown on any document, the document shall include the following:
(a)CA Public Resources Code § 8877(a) A statement that the geodetic coordinate value or values shown are a CGC83 value or values; exceptions shall be noted.
(b)CA Public Resources Code § 8877(b) The station or stations to which the CGC83 value or values are referenced and connected and the geodetic coordinate value or values and the published or stated accuracy or accuracies of said reference station or stations.
(c)CA Public Resources Code § 8877(c) The epoch of the CGC83 value or values shown. The epoch shall conform to provisions of subdivision (b) of Section 8876.
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Section § 8878
This law states that using CGC83 is not mandatory for anyone, including individuals, companies, or government agencies. It's entirely up to them whether they want to use it or not.
The use of CGC83 by any person, firm, or governmental agency is optional.
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Section § 8879
This law states that it won't change or cancel any official land titles, boundaries, or geographic coordinates, even if those coordinates don't match the guidelines of this chapter, except as mentioned in another part of the law, Section 8872.
This chapter does not impair or invalidate land titles, legal descriptions, or jurisdictional or land boundaries and, further, this chapter does not impair or invalidate references to, or the use of, datums or latitude, longitude, or ellipsoid height values or other geodetic coordinate values that do not conform to this chapter except as specified in Section 8872.
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Section § 8880
This law allows for the use of new surveying technologies and methods even if there aren't any official specifications or standards published for them yet.
This chapter does not prohibit the use of new surveying technologies or techniques for which FGCS specifications or other accepted specifications have not yet been published.
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