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About, and what to watch for

Not for navigation

These models are for looking at and for planning on a table. Nothing here is a chart, none of the sources is certified for navigation, and the Canadian bathymetry is published as explicitly non-navigational. Do not take a depth off a print.

What the depths mean

Heights and depths are relative to the vertical datum of the source data — close to mean sea level (CGVD2013 for the lidar) — not chart datum. Chart datum on this coast is lower low water, which sits well below mean sea level, so a contour labelled 15 here is not the 15 m line on the chart: expect a charted depth to be shallower by something like one to two metres. Where lidar and seabed grid overlap on flat ground the grid is shifted onto the lidar's datum (about 1.7 m round Victoria), so the waterline is the lidar's. The exact datum of each seabed grid has not been verified for this project.

Where it works

Anywhere the elevation grids reach: the BC coast from Juan de Fuca to Queen Charlotte Sound (10 m), Puget Sound and central California (about 3 m). Turn on Data coverage outlines in the map's layer menu to see them. Land detail comes from lidar, which is Canada only, and the best of it — LidarBC point clouds — British Columbia only. Elsewhere the land is drawn from the same grid as the seabed.

Known limits

• Piers can come out as a comb of slots wherever LidarBC point clouds are not used: the national lidar product sees the water between the piles. Tick Fetch LidarBC point clouds.
• A ship alongside on survey day stays in the model in bare-earth mode: over water there is no ground beneath it to tell it from a pier. Mark it as bad lidar in the preview.
• Seabed detail is limited by its source — 10 m postings on the Canadian side. Rocks smaller than about 20 m across are not there to be printed.
• Survey holes: where no vessel could go — over drying rocks, under structures — grids are filled from their surroundings and can be badly wrong. Mark them as bad seabed.
• Contour labels are sparse on steep ground; they are only placed where a line runs straight enough to read, and lines themselves thin out on cliffs.

Data and attribution

• LidarBC point clouds — Province of British Columbia, Open Government Licence – British Columbia.
• High Resolution Digital Elevation Model (HRDEM) — Natural Resources Canada, Open Government Licence – Canada.
• Canada west coast bathymetry — Canadian Hydrographic Service non-navigational (NONNA) data and related public grids.
• Puget Sound and central California — NOAA NCEI Continuously Updated DEM (CUDEM).
• Basemaps — Esri, Maxar, GEBCO, NOAA; OpenStreetMap contributors.

The licence terms of each source have not been formally reviewed. If you publish or sell a model, check them yourself and credit the sources above.

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