1. On the effective validation of charted soundings and depth curves
C. Kastrisios, B. Calder, G. Masetti, UNH CCOM/JHC
Peter Holmberg, NOAA OCS/HSD/PHB
U.S. Hydro 2019 Conference – March , Biloxi, MS

2. Soundings & Depth Curves
Representation of submarine relief on charts
Safety Constraint
Source: NOAA Nautical Chart Catalog and Chart Viewer

3. Shoal-biased Pattern “Triangle test” “Edge test”
“No actual sounding exists within a triangle of selected soundings which is less than the least of any of the soundings forming the triangle“
“No actual sounding exists between two adjacent selected soundings forming an edge of the triangle which is less than the lesser of the two selected soundings “
Source: Kastrisios, C., B.R. Calder, G. Masetti, and P. Holmberg “Towards Automated Validation of Charted
Soundings: Existing Tests and Limitations.” Geo-spatial Information Science. Taylor & Francis (In Press)

4. Chart Compilation and Sounding Validation
Existing chart
New survey
Source soundings from
New survey, or
Larger scale chart
Selected
Soundings
Flagged
Soundings
Final Selection is
applied to chart
Source of data: NOAA/OCS/MCD

5. Aim Automate the validation process Replicate what cartographers do:
In open areas
Triangles from selected soundings
Near and within linear features
Areas of dominance
Near the boundaries of the updated area
“Incorporate” bathymetry from adjoining areas

6. Implementation Automate the validation process
Replicate what cartographers do:
Use all the available bathymetric information
Import bathymetry from adjoining areas (~buffer)
Generate Conforming Delaunay triangulation
Source: Kastrisios, C., B.R. Calder, G. Masetti, and P. Holmberg “Towards Automated Validation of Charted
Soundings: Existing Tests and Limitations.” Geo-spatial Information Science. Taylor & Francis (In Press)

7. Results TT  Improved performance near linear features
Source: Kastrisios, C., B.R. Calder, G. Masetti, and P. Holmberg “Towards Automated Validation of Charted
Soundings: Existing Tests and Limitations.” Geo-spatial Information Science. Taylor & Francis (In Press)

8. Results ET  first implementation effort
ET identifies shoals that the TT fails to identify
Validation based on TT only is strongly inadvisable
Source: Kastrisios, C., B.R. Calder, G. Masetti, and P. Holmberg “Towards Automated Validation of Charted
Soundings: Existing Tests and Limitations.” Geo-spatial Information Science. Taylor & Francis (In Press)

9. TT-ET’s “Intrinsic” Limitation
“Intrinsic”: due to their definition
Source soundings that deviate significantly from the expected may not be found
TT and ET insufficient toward a fully automated solution
Source: Kastrisios, C., B.R. Calder, G. Masetti, and P. Holmberg “Towards Automated Validation of Charted
Soundings: Existing Tests and Limitations.” Geo-spatial Information Science. Taylor & Francis (In Press)

10. TT-ET’s “Intrinsic” Limitation
Rough discretization
Shallowest of the 3 (or 2) selected soundings serves as the validation depth
Only eminences above the validation depth are flagged (“B”)
The slope of the sea-bottom is disregarded
Source: Kastrisios, C., B.R. Calder, G. Masetti, and P. Holmberg “Towards Automated Validation of Charted
Soundings: Existing Tests and Limitations.” Geo-spatial Information Science. Taylor & Francis (In Press)

11. TT-ET’s “Intrinsic” Limitation
Shoal biased pattern may be violated
Actual depth may be significantly shoaler than the expected
US5AK4DM , H-12865, CATZOC A1
Source: Kastrisios, C., B.R. Calder, G. Masetti, and P. Holmberg “Towards Automated Validation of Charted
Soundings: Existing Tests and Limitations.” Geo-spatial Information Science. Taylor & Francis (In Press)

12. Surface Interpolation Test
Source soundings are compared to the expected depth at the location
“Expected depth” is derived from the charted bathymetric information with interpolation
Tolerance may be applied (e.g., CATZOC values)

13. Surface Interpolation Test
ST identifies shoals that TT and ET may not due to their “intrinsic limitation”
ST reduces the number of insignificant flags (those within tolerance)
Interpolation methods implemented:
Linear
Natural Neighbors ++

14. “Doing little things well is a step toward doing big things better”
Vincent van Gogh
This work is supported by the National Oceanic and Atmospheric Administration [grant number NA15NOS ]