Vertical Section Visualizer beta

What This Page Does

This experimental page produces an interpolated vertical section along a selected axis or A–B line. It is intended for exploratory inspection, not final scientific interpretation without independent validation.

Basic Workflow

1. Select a reference dataset and set the shared filters.
2. Choose Axis-based mode, or choose A-B section and enter endpoints or draw a line on the selector map.
3. Set the corridor half-width. In A-B mode, only observations inside this corridor are projected onto the section.
4. Select a target parameter, bathymetry source, and display settings.
5. Inspect the colour and line section views, the Section Map, and the section table.
6. Narrow the filters or corridor if too many rows remain for interpolation.

Uploaded Data In Section Calculations

Upload or reuse session data with longitude, latitude, depth, and the selected target parameter. In A-B mode, uploaded samples inside the active corridor are projected onto the section line. In Axis-based mode, they use the same axis coordinate and distance origin as the reference data. Select Uploaded data in the shared Data filtering form to include valid uploaded rows in section projection, interpolation, contouring, and the observed-depth seafloor fallback. Deselecting it removes those rows from the calculation and display. Uploaded samples remain distinct foreground markers in the selector map, section plots, and Section Map. The page reports valid and missing/invalid counts for the selected target parameter.

Main Controls

• Shared user-data upload, column assignment, and marker-style panels
• Common Data filtering form used by the other visualization pages
• Section mode — Axis-based (Longitude_degE, Latitude_degN, or Distance_km) or A-B section.
• A-B endpoints / Draw on map — manual endpoints always work; drawing requires folium and streamlit-folium and is unavailable in Coastline (offline) mode.
• Half-width of section corridor and Show section corridor.
• Bathymetry source — built-in GEBCO, an uploaded CSV/Excel table, or deepest observations. GEBCO is used only for A-B sections; a readable fallback is shown if it cannot supply a profile.
• Resolution, Smoothing (visual only), and the maximum row count used for interpolation. The page enforces an internal hard cap to protect shared/Cloud environments.
• Target-parameter range, colormap, and horizontal colour-bar controls.

Outputs

• Colour-filled and contour-line section views
• A Section Map showing the line, corridor, and observations used
• Expandable table of the rows used for the section calculation

Notes And Limitations

• This page is beta. Vertical-section interpolation is scientifically and computationally sensitive; validate the method and display settings before using an output as a final analysis figure.
• The interpolation uses a safe fallback sequence (cubic, then linear, then nearest neighbour when needed). Cells filled only by nearest-neighbour extrapolation are visually marked as lower-confidence areas; they are not observations.
• Smoothing changes the displayed interpolated grid only. It does not add observations or demonstrate physical continuity.
• The seafloor is a display constraint, not a bathymetric analysis. Where a selected source cannot provide a usable profile, the page falls back to observed maximum depth.
• A line that directly crosses the antimeridian (180°/−180°) uses a local planar approximation not validated for that geometry. Treat such output as a rough visual reference only.
• Browser uploads are session-only and never modify reference datasets or persistent User Excel data.