What you'll do

Create and edit GIS points, lines and polygons inside SWMMVis. Use them as mesh domains, breaklines, refinement regions, corridors and parameter zones, or as source features for importing SWMM objects. Feature layers keep their geometry and attributes in a GeoPackage beside the model; the project remembers their roles, styling and elevation settings.

Drawing a feature does not by itself create a SWMM node, conduit or subcatchment. Use Model → Import Feature Layer… when you want to convert features into model objects (12 — Editing the Network on the Map).

Where to find it

Features ribbon: Select; New Layer; Edit Mode; Delete; Point; Line; Polygon; Add Part; Add Hole; Edit Vertices; Move.
View → Panels → Features (Ctrl+Alt+0): layers, fields, attributes, vertex coordinates and elevation controls.
Model → Feature Layers: the corresponding layer and editing commands.

The Features ribbon with layer creation; drawing and geometry editing commands

Step-by-step

Create a layer

Open a project and save it to a named location. SWMMVis needs that location to create the companion <model>.features.gpkg file.
Choose Features → New Layer, or New… in the Features panel.
Choose What is it for? and enter a Name. The role supplies appropriate geometry types and fields; read the role's explanation before continuing.
Choose the geometry type. Choose a multipart type now if one feature may have several separate parts. The geometry type cannot be changed after creation.
Review the Fields table. Required fields are retained. Select the optional fields you need, edit their defaults, or use Add custom field….
Expand Elevation (Z) if needed and choose a source. The choice of 2D or 3D storage is also fixed when the layer is created.
Choose Create. Select the new layer in the Features panel and enable Edit Mode before drawing or changing its data.

The new layer uses the canvas CRS. When none is set, its coordinates are stored as drawn; assign the correct CRS before combining it with other spatial data. Horizontal CRS units and elevation units are separate choices; see 06 — Coordinate Reference Systems.

New Feature Layer with the role; geometry; fields and elevation settings

Choose the role

Role	Geometry and fields	How it is used
General	Any supported geometry; `name` plus custom fields	An editable GIS layer for your own data
Mesh domain boundary	Polygon or multipolygon; required `name`	The area to mesh; interior rings become holes
Breaklines / hard points	Lines or points; optional `name`; elevation source	Lines mesh edges follow and points the mesh must include; the mesher reads geometry and Z
Mesh regions	Polygons; cell size `h`; cell mode `cells`; optional `tag`	Local sizing and alignment; `h = 0` uses the model cell size. Quads if four-sided allows aligned quads for four-sided regions; Triangles keeps triangles
Corridors	Line or multiline; total `width`; optional `tag`	Road or river centerlines used by mesh corridor sources
Parameter zones	Polygons; optional `mannings_n`; `init_depth`; `landuse`; `hsg`	Sources for assigning cell attributes; select and map them in the assignment workflow
SWMM delineation	Geometry appropriate for import; object naming/type fields	Source geometry for Import Feature Layer…
Boundary-condition lines	Lines; boundary type; head; slope; flow; time-series/curve references; group; conveyance	Stores proposed boundary data. Automatic assignment from these lines is not implemented; assign active boundary conditions with Mesh Editing

A role helps construct the schema; it does not automatically apply its values to an existing mesh. Choose the layer in the relevant mesh-generation or assignment dialog, inspect its preview and complete that operation separately.

A Mesh regions layer showing cell-size and cell-mode defaults

Style each layer

Right-click a feature layer in the Layers panel and choose Properties → Symbology. Use Marker (points), Line, or Polygon to change its colours, sizes, line styles and outlines. The Labels tab controls its labels. Each layer has its own settings, including layers with the same geometry type or role. Changes preview on the map; Apply or OK keeps them and Cancel discards changes since the last Apply. Save the project to retain each layer's styling for the next session.

Draw and modify geometry

The selected layer in the Features panel is the target of drawing and editing. Check its name before using a tool, especially when several similar layers are visible. Tools for incompatible geometry types are unavailable.

Tool or gesture	Use
Point	Place a feature at the clicked map position
Line / Polygon	Click vertices in sequence; double-click or press Enter to finish
Right-click while drawing	Remove the most recent vertex; cancel when there is no earlier segment
Esc while drawing	Cancel the unfinished geometry
Add Part	Add another part to a selected feature in a compatible multipart layer
Add Hole	Draw an interior ring in a selected polygon
Edit Vertices	Select and move existing vertices; use the vertex context menu for available edits
Move	Move the selected feature on the map
Delete	Delete selected features while Edit Mode is active
Select	Return to selection when you finish drawing or editing

Geometry edits participate in the project's undo history. Use Undo immediately if the wrong layer or feature was changed. Unfinished geometry must satisfy its type's minimum vertex count and validity rules before it can be committed.

FIGURE PLACEHOLDERdocs/manual/images/12a_feature_vertices.png

A selected feature with its part; ring and vertex coordinates in the Features panel

Edit attributes and coordinates

The Attributes section describes the layer's columns; the Features table contains the values of individual features. With Edit Mode enabled, edit cells in the Features table. Its selection is linked to the map. Add column… and Remove column change the schema; removing a column also removes its values from every feature, so review the confirmation carefully.

Select exactly one feature to inspect the Vertices table. Its part and ring columns distinguish multipart geometry and holes. X and Y are in the layer's CRS. Editable Z values depend on the layer's elevation policy. A geometry with too many vertices to list directs you to the map vertex tool.

Update fields to role… previews schema changes for an older layer: additions, renames, defaults and value lists. Optional retired columns are explicitly listed for removal. Review the preview, then choose Update; the update is one undo operation. It does not implicitly reinterpret every existing feature value.

Assign elevations

Elevation setting	Meaning
None — 2D layer	Store horizontal geometry without Z
Constant source and Value	Store a fixed elevation
Raster source; From layer; Raster band	Sample a loaded raster at the feature vertices
2D mesh source and From layer	Sample elevations from a loaded mesh
Z conversion (×)	Multiply sampled elevations to convert vertical units
Densify before sampling	Insert intermediate vertices at the specified spacing before sampling; useful where terrain changes between drawn vertices
Re-sample when a vertex moves	Refresh a moved vertex's elevation from its configured source
Resample Z now	Refresh the layer's features as one undo operation

Read the coverage warning when sampling: a feature can extend beyond the raster or mesh. Check the resulting Z values and the source's units before using the layer as a breakline or channel input. A 2D layer cannot acquire 3D storage merely by changing a display setting; create an appropriate 3D layer when needed.

Import export and persistence

Use Import… in the Features panel to copy compatible vector data or a SWMM object class into the selected editable layer. Review the source, geometry and field choices before importing. Use Export… to write a selected feature layer for use elsewhere. See 07 — Layers and Data Sources for loading external GIS data and 12 — Editing the Network on the Map for the separate GIS-to-SWMM conversion workflow.

Feature edits are written to the companion GeoPackage as they are applied. Save retains the project's layer references and display settings; it is not a rollback boundary for the GeoPackage. Use Undo to reverse feature edits within the session. Keep the GeoPackage with the project when transferring it. Remove removes a feature layer from the map; its table remains in the GeoPackage. Removing a map layer and deleting its features are different actions.

Tips and gotchas

Save the project before creating its first feature layer.
Check the selected target layer and Edit Mode before modifying geometry.
Plan multipart and 3D storage before creating the layer.
Creating or editing a source layer does not regenerate the mesh or reapply cell properties automatically.
Boundary-condition line attributes are preparatory data; use the mesh edge editor to assign working boundary conditions in this build.
Check sampled Z values and conversion factors before generating a mesh.

12 — Editing the Network on the Map — network editing and GIS-to-SWMM import
07 — Layers and Data Sources — GIS sources and layer management
06 — Coordinate Reference Systems — coordinate systems and transformations
19 — 2D Overland Flow: Meshes, Cell Parameters, Boundary Conditions and 1D–2D Coupling — mesh domains; breaklines; regions; corridors and assignments
03 — Working with Projects — project storage and portability