EPSG Dataset :: v12.042test

Geodetic Awareness

[to do: check/copy some text and images from GIGS or GN 373-1)

Geodetic awarenss is important for operational decision making and to avoid HSE risk because:

Most data have locations.
Decisions rely on correctness of these locations.
Coordinates are meaningless without a Coordinate Reference System (CRS).

This means that coordinate data must always have a well defined CRS associated with them. This is made easy by referring to the EPSG Dataset, when an EPSG CRS code is associated with the coordinates. The process of associating a CRS with coordinates is called geodetic referencing, and this is crucial to make reliable decisions.

Data is unambiguously referenced to a unique location by means of Coordinates and a CRS. Coordinates can't be measured like temperature or mass. Instead, coordinates are relative to a chosen starting point (the CRS). Hence, when you see coordinates you should always think “from where?” and never assume.

A Coordinate Reference System (CRS) sets the starting point and the axes to which coordinates refer. Coordinates by themselves are not unique. Only together with their CRS they uniquely define a location.

Before datasets can be merged or co-visualized they need to be transformed into a common CRS so that they align.

(random image to be replaced)

Geodetic Integrity

Now that we understand that a CRS is required, and that there is a big risk of getting to the wrong location if we do not properly keep track of these critical metadata, we can define geodetic integrity.

Geodetic (geospatial) integrity is the state in which spatial data are uniquely referenced to a location. This requires:

That data have coordinates.
That these are associated with a well-defined coordinate reference system (CRS).
And that data are accompanied by a history record of checks and operations applied.

The EPSG Dataset facilitates this by utilizing the ISO 19111 standard: Referencing locations by coordinates. This enables and facilitates software interoperability, the exchange of data between applications.

The EPSG Dataset contains definitions of coordinate reference system (CRS) and transformations and conversions between them. The Guidance Notes 7 series provides users with concise background information, clear definitions (including mathematical formulas), examples, and discussion. Those reports are intended for end users such as geodesists and data managers at energy companies that seek geodetic information in a specific project area or new working area.

Maintaining Geodetic Integrity

However, once we have achieved geodetic integrity we have to be careful that coordinates remain associated with the correct CRS, and that engines apply the correct math, while precision is not eroded.

Whenever one transfers or stores data in software systems, or apply conversions or transformations to change the CRS.
That is done by checking software, guidance notes and work procedures and by raising competences of staff in Industry.

How to avoid Geodetic Failures?

n Use an appropriate projected coordinate reference system such that calculations in the map plane yield accurate results (e.g., in Wells planning software and geological modeling applications).

n Use an appropriate coordinate transformation and consistently use it such that datasets can be merged and co-visualized (ideally avoid transformations by acquiring and storing data in the same CRS!)

n Always show the CRS that is associated with the coordinates and keep track of coordinate operations that have been applied on the data (such that geodetic integrity can be verified).

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Wildcard	Example
% or *	Any wildcard characters
? or _	One wildcard character
[ - ]	[ - ] Range e.g. N[a-c] will return all geodetic objects that contains a string starting with the letter 'N' or 'n' followed by any of the letters contained within the range specified within the square bracket, e.g. letters a, b and c.
\|	Or e.g. E[a\|e]M will return all geodetic objects that contains a string starting with the letter E(e), ends with the letter M(m) and also contain either the letter a or letter e.