Select Primitives: select triangles or points with lasso or brush

Select Primitives is the main selection tool of MeshInspector. It selects triangles of meshes and points of point clouds inside a shape you draw on the screen. Use it to mark scan noise, a damaged area or a part of a model before you delete it, copy it to a new object or repair it.

How to use the Select Primitives tool

1. Select the mesh or point cloud in the Scene Tree. The tool works only on selected objects.
2. Click Select › Select Primitives, or press Ctrl+W (Cmd+W on macOS). The button is also on the toolbar above the viewport. The Select Primitives panel opens.
3. Pick a mode at the top of the panel and draw in the viewport with the left mouse button. Selected triangles and points turn red.
4. Hold a modifier key to add to the selection or remove from it (see Modifier keys).
5. Close the panel with the cross in its header or click Select Primitives again. The selection stays on the object for the next tool.

Selection modes

All modes select in screen space: what lies inside the shape you draw, as seen from the camera.

Mode	How you draw	When to use
Lasso	Hold the left mouse button and draw a free curve; the area inside it is selected when you release.	Irregular areas: noise around a scan, a feature with a curved outline. Default mode.
Rect	Drag a rectangle.	Fast rough selection of a large area, a whole side or a slice of a model.
Polygon	Click the corners of a polygon. Click again on the first point, or press Enter, to close it.	Areas with straight edges where a precise outline matters.
Brush	Hold the left mouse button and paint; everything under the brush stroke is selected.	Narrow strips and touch-ups along an edge.
Pick	Click once.	One triangle or one point at a time, for fine corrections.

Lasso example

Panel settings

Setting	What it does	Default
Select Back Triangles	Also selects triangles and points that face away from the camera.	On
Select Only Visible Triangles	Selects only what you see; triangles and points hidden behind other surfaces are skipped.	Off
Brush Radius (Brush mode only)	Size of the brush in screen pixels, from 1 to 500 px. You can also hold Ctrl (Cmd on macOS) and scroll the mouse wheel in the viewport.	8 px

With the default settings a shape selects through the whole model, including its far side and other selected objects behind it. To select only the surface you are looking at, turn on Select Only Visible Triangles.

The Hotkeys block at the bottom of the panel lists the keys of the current mode.

Modifier keys

Hold the key while you draw or click:

Key	Result (label in the Hotkeys block)
No key	Select New: the new shape replaces the previous selection.
Ctrl (Cmd on macOS)	Add to Previous.
Shift	Unselect in Previous: removes the shape from the selection.
Shift+Ctrl (Shift+Cmd on macOS)	Reverse Selection: inside the shape, selected elements become unselected and vice versa.
Ctrl+A (Cmd+A on macOS)	Select All Primitives of the selected objects.
Enter (Polygon mode)	Close Polyline and select.

If you prefer to add to the selection without holding a key, open Settings › Application and set Default Selection Behavior to Append selection. Then a shape without a key adds to the selection and Ctrl (Cmd) starts a new one.

Meshes and point clouds

• On a mesh, the tool selects triangles. To set a selection border that follows the surface, or to select edges, use Triangles Selector and Edge Selector from the drop-down arrow next to Select Primitives; see Triangles Selector.
• On a point cloud, the same modes select points. While the panel is open, a selected cloud is drawn with all its points, so the selection catches every point under the shape.

What to do next

• Grow or refine the selection with Expand Selection or Shrink Selection, or flip it with Inverse Selection.
• Remove the selected area with Delete Selected.
• Copy it to a separate object with Selection to Object.
• Start over with Clear Selections (Ctrl+X, Cmd+X on macOS).

For an overview of all selection tools, see Selection basics.