Attribute: Category of zone of confidence in data

CORRECTION to attribute class in S-57 Edition 3.1.2

Changes made to the definitions of the attribute CATZOC.


Acronym: CATZOC

Code: 72

Attribute type: E

Expected input:

ID Meaning INT 1 M-4
1 zone of confidence A1
      
      
2 zone of confidence A2
      
      
3 zone of confidence B
      
      
4 zone of confidence C
      
      
5 zone of confidence D
      
      
6 zone of confidence U (data not assessed)
      
      

Object Classes that use CATZOC

Definitions - ZOC Table:

1 2 3 4 5
ZOC Position Accuracy Depth Accuracy Seafloor Coverage Typical Survey Characteristics
A1 5 m + 5% depth =0.50 + 1%d Full area search undertaken. Significant seafloor features detected and depths measured. Controlled, systematic survey high position and depth accuracy achieved using DGPS or a minimum three high quality lines of position (LOP) and a multibeam, channel or mechanical sweep system.
Depth (m) Accuracy(m)
  10
  30
 100
1000
     
  0.6
  0.8
  1.5
 10.5
     
A2 20 m = 1.00 + 2%d Full area search undertaken. Significant seafloor features detected and depths measured. Controlled, systematic survey achieving position and depth accuracy less than ZOC A1 and using a modern survey echosounder and a sonar or mechanical sweep system.
Depth (m) Accuracy(m)
  10
  30
 100
1000
     
  1.2
  1.6
  3.0
 21.0
     
B 50 m = 1.00 + 2%d Full area search not achieved; uncharted features, hazardous to surface navigation are not expected but may exist. Controlled, systematic survey achieving similar depth but lesser position accuracy less than ZOC A2 and using a modern survey echosounder, but no sonar or mechanical sweep system.
Depth (m) Accuracy(m)
  10
  30
 100
1000
     
 1.2
 1.6
 3.0
 21.0
     
C 500 m = 2.00 + 5%d Full area search not achieved, depth anomalies may be expected. Low accuracy survey or data collected on an opportunity basis such as soundings on passage.
Depth (m) Accuracy(m)
  10
  30
 100
1000
     
 2.5
 3.5
 7.0
 52.0
     
D Worse than ZOC C Worse than ZOC C Full area search not achieved, large depth anomalies may be expected. Poor quality data or data that cannot be quality assessed due to lack of information.
U Unassessed - The quality of the bathymetric data has yet to be assessed.

Remarks:
To decide on a ZOC Category, all conditions outlined in columns 2 to 4 of the table must be met.

Explanatory notes quoted in the table:

1. ZOC
The allocation of a ZOC indicates that particular data meets minimum criteria for position and depth accuracy and seafloor coverage defined in this Table. ZOC categories reflect a charting standard and not just a hydrographic survey standard. Depth and position accuracies specified for each ZOC category refer to the errors of the final depicted soundings and include not only survey errors but also other errors introduced in the chart production process. Data may be further qualified by Object Class "Quality of Data" (M_QUAL) sub-attributes as follows:

Position accuracy
Position Accuracy of depicted soundings at 95% CI (2.45 sigma) with respect to the given datum. It is the cumulative error and includes survey, transformation and digitizing errors etc. Position accuracy need not be rigorously computed for ZOCs B, C and D but may be estimated based on type of equipment, calibration regime, historical accuracy etc.

2. Position accuracy
Position Accuracy of depicted soundings at 95% CI (2.45 sigma) with respect to the given datum. It is the cumulative error and includes survey, transformation and digitizing errors etc. Position accuracy need not be rigorously computed for ZOCs B, C and D but may be estimated based on type of equipment, calibration regime, historical accuracy etc.

4. Significant seafloor features :
Significant seafloor features are defined as those rising above depicted depths by more than:

      
Depth   
Significant Feature
a. <40m 2m
b. >40m 10% depth

A full seafloor search indicates that a systematic survey was conducted using detection systems, depth measurement systems, procedures, and trained personnel designed to detect and measure depths on significant seafloor features. Significant features are included on the chart as scale allows. It is impossible to guarantee that no significant feature could remain undetected, and significant features may have become present in the area since the time of the survey.

5. Typical survey characteristics
These descriptions should be seen as indicative examples only.

6. Controlled, systematic surveys (ZOC A1, A2 and B)
Surveys comprising planned survey lines, on a geodetic datum that can be transformed to WGS 84.

7. Modern survey echosounder
A high precision single beam depth measuring equipment, generally including all survey echosounders designed post 1970.