HorizontalAccuracy

Absolute accuracy

Line	Component	Measure Description
1	Name	absolute circular error at 90 % significance level of biased data
2	Alias	CMAS
3	Data quality element	Absolute or External Positional Accuracy
4	Data quality basic measure
5	Definition	absolute horizontal accuracy of the data’s coordinates, expressed in terms of circular error at 90 % probability given that a bias is present
6	Description	See STANAG 2215 ed7 Appendix 2
7	Parameter
8	Data quality value type	Measure
9	Data quality value structure
10	Source reference	NATO STANAG 2215 ISO 19157 measure n°48
11	Example
12	Identifier	http://dgiwg.org/metadata/qualityMeasure/CMAS

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Line	Component	Measure Description
1	Name	absolute circular error at 90 % significance level of biased data
2	Alias	ACE
3	Element name	absolute or external accuracy
4	Basic measure	not applicable
5	Definition	absolute horizontal accuracy of the data’s coordinates, expressed in terms of circular error at 90 % probability given that a bias is present
6	Description	A comparison of the data (source) and the control (reference) is calculated in the following manner: 1. Calculate the absolute error in the horizontal dimension at each point: Δ H i = ( source X i − reference X i ) 2 + ( source Y i − reference Y i ) 2 for i = 1…N 2. Calculate the mean horizontal error: μ H = ( ∑ Δ H i ) N 3. Calculate the standard deviation of the horizontal errors: σ H = ∑ ( Δ H i − μ H ) 2 ( N − 1 ) 4. Calculate the ratio of the absolute value of the mean error to the standard deviation: ratio = | μ H | / σ H 5. If ratio > 1 , 4 , then k = 1 , 281   5 6. If ratio ≤ 1,4, then calculate k, the ratio of the mean to the standard deviation, using a cubic polynomial fit through the tabular values as defined in the CRC Handbook of Tables for Probability and Statistics [ 20 ] k = 1 , 643   5 − ( 0 , 999   556 × ratio ) + ( 0 , 923   237 × ratio 2 ) − ( 0 , 282   533 × ratio 3 ) 7. Compute CE90 for the source: CE90 source = | μ H | + ( k × σ H ) 8. Compute absolute CE90: CE90 abs = CE90 reference 2 + CE90 source 2
7	Parameter	Name: Sample size Definition: minimum of 30 points is normally used but may not always be possible depending on identifiable control points. For feature level attribution sample 10 % of the feature population. Value Type: Real
8	Value type	Measure
9	Value structure	-
10	Source reference	ISO 19157 Measure n° 49 1. Mapping, Charting and Geodesy Accuracy (Reference[ 21 ]) 2. Handbook of Tables for Probability and Statistics (Reference[ 20 ])
11	Example	-
12	Identifier	http://dgiwg.org/metadata/qualityMeasure/ACE

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Line	Component	Measure Description
1	Name	Cartography of quality zones
2	Alias	CQZ
3	Data quality element	Absolute or External Positional Accuracy
4	not applicable
5	Definition	Cartography of horizontal quality zones (defined by their boundaries in GML or Shapefile)
6	Description	Information related to the result of a quality evaluation of the dataset on absolute horizontal accuracy (CE90) covResult : - format = GML (version 3.3) or SHP (version 1.0) - geometry = surface - content = (contentType=’qualityInformation’) - file = (name=’link to the GML or SHP file) - and (description=”Cartography of quality zones”)
7	Parameter
8	Data quality value type	GM_Surface
9	Data quality value structure	coverage
10	Source reference	http://dgiwg.org/metadata/qualityMeasure/ACE ISO 19157 measure n°48
11	Example
12	Identifier	http://www.dgiwg.org/metadata/qualityMeasure/CQZ

Relative accuracy

Line	Component	Measure Description
1	Name	Point-to-point horizontal accuracy
2	Alias	RelCE90
3	Data quality element	Relative or internal accuracy
4	Data quality basic measure
5	Definition	Uncertainty in the difference in horizontal positions between any 2 points. The value is expressed as a circular error at the 90% confidence level.
6	Description	See STANAG 2215 ed7 Appendix 2
7	Parameter
8	Data quality value type	Measure
9	Data quality value structure
10	Source reference	NATO STANAG 2215
11	Example
12	Identifier	http://dgiwg.org/metadata/qualityMeasure/RelCE90