.. _quickstart_from_scratch: ============================== Quickstart - from scratch ============================== The :ref:`quickstart` chapter walks you through the **example project**. This chapter shows the same workflow but **starting with a blank QGIS project**: how to draw your first leg, set its width, bring in depth and object data, and produce a first risk number. .. contents:: In this chapter :local: :depth: 1 1. Open the plugin (no project loaded) ========================================= Open QGIS, click the OMRAT icon, and dock the panel on the right. With nothing loaded the Routes tab looks like this: .. figure:: _static/screenshots/quickstart/qs_01_empty_routes_tab.png :width: 80% :alt: Empty Routes tab, before the first leg is drawn. Routes tab on a fresh project. ``twRouteList`` is empty and the distribution panel below shows zeroed defaults. .. figure:: _static/screenshots/quickstart/qs_02_canvas_blank.png :width: 80% :alt: Empty QGIS canvas with no layers. The QGIS canvas before any layer is added. Most users begin by adding a basemap (XYZ Tiles → OpenStreetMap is fine). 2. Place legs on the map ========================== A *leg* is a single straight segment of a route. OMRAT calculates risk **per leg**, so a curved or branching route is approximated with several short legs joined end to end. To draw a leg: #. Click **Place leg** on the Routes tab toolbar. The cursor turns into a crosshair. #. Click the start point on the canvas. #. Click the end point. The leg is added to ``twRouteList`` and a blue line appears on the canvas. #. Repeat for each leg. Click **Stop route** to leave place-leg mode. After one leg the Routes tab shows the new row: .. figure:: _static/screenshots/quickstart/qs_03_route_after_first_leg.png :width: 80% :alt: Routes tab after a single leg has been placed. The first leg appears in ``twRouteList`` (Segment 1, Route 1). Adjust **Width** to the half-width of the corridor in metres (5000 = a 5 km wide corridor). .. figure:: _static/screenshots/quickstart/qs_04_canvas_with_legs.png :width: 80% :alt: QGIS canvas showing the placed leg as a blue line. The leg as drawn on the canvas. Two grey "offset" lines mark the width of the corridor. .. tip:: Endpoints that exactly coincide between legs (within metres, not visually) are treated as **shared vertices**: dragging one with the QGIS Vertex Tool moves every connected leg's endpoint together, so a curved route stays connected when you re-route. 3. Bring in depth data ======================== Powered grounding and drifting grounding both rely on a depth contour layer. OMRAT consumes depth polygons (one per discrete depth value). Where to get depth data: * **EMODnet Bathymetry** (https://emodnet.ec.europa.eu/en/bathymetry) - free 1/16 arc-min DTM for European seas. Download a tile, contour it in QGIS (*Raster → Extraction → Contour Polygons*), then load the resulting polygons into the Depths tab. * **GEBCO** (https://www.gebco.net/) - global 15-arc-second bathymetry. Same workflow. * **Local hydrographic offices** - national bathymetry products are usually higher resolution but require a license. * **ENCs** (Electronic Navigational Charts) - if you have access to S-57/S-101 chart data, the *Depth Areas* (DEPARE) layer is exactly what OMRAT wants. Once you have polygons in QGIS, switch to the **Depths** tab and use **Add depth from layer** to import them. The tab is empty before any depths are added: .. figure:: _static/screenshots/quickstart/qs_05_depths_tab_empty.png :width: 80% :alt: Empty Depths tab. Depths tab on a fresh project. Each row links one polygon to its depth value (in metres, positive downwards). 4. Define obstacles (objects) ============================== Bridges, wind-park footprints, and other surface structures go on the **Objects** tab. The workflow is identical to Depths: import a polygon layer (or digitise polygons by hand) and set the structure's height in metres above sea level. .. figure:: _static/screenshots/quickstart/qs_06_objects_tab_empty.png :width: 80% :alt: Empty Objects tab. Objects tab on a fresh project. Powered allision and drifting allision use the polygons listed here. Common sources for object polygons: * **OpenStreetMap** - bridges, piers and offshore wind farms tagged ``man_made=*`` are usually present. * **EMODnet Human Activities** - offshore platforms, wind-farm layouts. * **National marine spatial planning portals**. 5. Settings: drift, ship categories, causation, AIS ===================================================== Open the relevant **Settings** dialog from the dock's gear menu. .. figure:: _static/screenshots/quickstart/qs_07_drift_settings_wind_rose.png :width: 80% :alt: Drift Settings dialog showing the wind-rose. Drift Settings. The wind-rose drives drifting risk -- start from a uniform 1/8 distribution if you don't yet have site-specific data, then refine using a local meteorological reanalysis (ERA5, MERRA-2). The other Settings dialogs are documented in :ref:`user_guide`: * **Ship Categories** - the type/size matrix that maps AIS rows to the cells of the traffic table. * **Causation Factors** - the per-accident-type Pc values. * **AIS Connection** - host/database/user for the optional AIS Postgres database. If you don't have an AIS database, fill the traffic table in by hand on the Traffic tab. 6. Run the model ================== Switch to the **Run Analysis** tab, fill in: * **Name of the model** - a short slug for this scenario. * **File path** - a folder. Each Run writes three files into this folder: - ``_.gpkg`` - the result layers. - ``_.omrat`` - a snapshot of the inputs (read-only). - ``_results_.md`` - a Markdown report covering every accident type. Click **Run Model**. The Run button is greyed out until both fields are set, and a popup spells out which is missing if you click anyway. When the run finishes the **Accident probabilities** table populates with one row per accident type and a **View** button per row that opens the matching driver visualisation. 7. Inspect the results ======================== The **Previous runs** table at the top of the Run Analysis tab keeps every run. Select a row and click **Add selected run results to map** to load that run's GeoPackage as styled QGIS layers. Two runs can be compared side-by-side from the **Compare** tab. .. seealso:: * :ref:`quickstart` -- same flow, but with the example project. * :ref:`user_guide` -- detailed reference for every tab. * :ref:`concepts` -- glossary of the OMRAT-specific vocabulary.