Italian Hydrographic Institute Guidance on Data Quality Aspects
Italian ENC production process, allocation of CATZOC values, and analysis of S-57 feature objects in hydrographic services and standards. Insights from the International Hydrographic Organization DQWG report.
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Hydrographic Services and Standards Committee DQWG Report of the Italian Hydrographic Institute Guidance on Data Quality Aspects: How IT allocates CATZOC values How IT allocates CATZOC values International Hydrographic Organization Organisation Hydrographique Internationale DQWG-13, IHO Secretariat, Monaco, 15-19 January 2018
Introduction Italian ENC portfolio consists of about 260 cells Italian ENC production process has changed ENCs were digitalized from paper charts use digital data or raw data about 50% of our ENC portfolio includes ENCs produced by digitalization the Italian general rules about the value of CATZOC on ENCs were changed, based on several factors. International Hydrographic Organization Organisation Hydrographique Internationale DQWG-13, IHO Secretariat, Monaco, 15-19 January 2018
Analysis/Discussion 1. The ENC production process: ENCs derived by digitalization: ZOC= B or C (value downgraded to include errors introduced in the digitalization process) ENCs produced from digital data or row data: ZOC = A1, A2, B, or C in accordance with the parameters described in the ZOC table (We do not downgrade the CATZOC value due to generalization process) International Hydrographic Organization Organisation Hydrographique Internationale DQWG-13, IHO Secretariat, Monaco, 15-19 January 2018
Analysis/Discussion 2. The S-57 Feature object used to encode the sea area: UNSARE: Up to Now ZOC = U (SWs and RENC) In Future no M_QUAL object should cover the UNSARE object if UNSARE object includes bathymetric features ZOC = D DRGARE: regularly maintained ZOC = A1 not regularly maintained ZOC = D International Hydrographic Organization Organisation Hydrographique Internationale DQWG-13, IHO Secretariat, Monaco, 15-19 January 2018
Analysis/Discussion DEPARE: bathymetric data are available ZOC = A1, A2, B, or C (No downgrade due to generalization process) blank area covered by larger scale ENCs ZOC D plus CTNARE no survey data are available and the sea area is included between the coastline and the outer limit of the surveyed area (either 0-2m or 0-5m): adjoining survey is ZOC equal to A1 or A2 ZOC = D adjoining survey is ZOC equal to B or C ZOC = B or C International Hydrographic Organization Organisation Hydrographique Internationale DQWG-13, IHO Secretariat, Monaco, 15-19 January 2018
Analysis/Discussion No survey data available - sea area included between the coastline and the outer limit of the surveyed area (either 0-2m or 0-5m) Blank area covered by larger scale ENCs International Hydrographic Organization Organisation Hydrographique Internationale DQWG-13, IHO Secretariat, Monaco, 15-19 January 2018
Analysis/Discussion 3. The Usage Band: UB 1(overview) and 2 (general): ZOC= D UB 3 (coastal), 4 (approach), 5 (harbour) and 6 (berthing): ZOC = A1, A2, B, or C in accordance with the parameters described in the ZOC table (We do not downgrade the CATZOC value due to generalization process) International Hydrographic Organization Organisation Hydrographique Internationale DQWG-13, IHO Secretariat, Monaco, 15-19 January 2018
Analysis/Discussion It is worth noting: CATZOC values are not downgraded due to the passage of time CATZOC downgraded due to the instability of bathymetry values are sometime CATZOC values are not downgraded due to the generalization to a smaller scale. International Hydrographic Organization Organisation Hydrographique Internationale DQWG-13, IHO Secretariat, Monaco, 15-19 January 2018
Conclusions Common rules on CATZOC value assessment have to be defined It is important to define a common operational approach on the following situations: ZOC values in UNSARE; How to downgrade CATZOC values due to the passage of time and the instability of bathymetry; How to downgrade CATZOC value due to the generalization to smaller scales; How to use CATZOC to assess the DEPARE included between the coastline and the outer limit of the surveyed area. International Hydrographic Organization Organisation Hydrographique Internationale DQWG-13, IHO Secretariat, Monaco, 15-19 January 2018
Action requested of DQWG The DQWG Members are invited to: a) note and discuss this paper; b) provide feedback. International Hydrographic Organization Organisation Hydrographique Internationale DQWG-13, IHO Secretariat, Monaco, 15-19 January 2018
