Selecting Objects in Rhino 8: A Guide to Windows, Lasso, and Filters

Rhino 8 includes tools ranging from window and crossing selection to lasso, brush, and property filters. The methods described in McNeel’s official documentation let you select objects before or while running editing commands in architectural modeling and visualization files. Because each tool selects different objects depending on the direction and shape of the selection area, choosing the right method can reduce the risk of editing the wrong geometry.

1. Use the selection direction correctly

To select an object, click it; clicking an empty area clears the selection. When selecting multiple objects with a rectangular area, the drag direction matters:

1. Drag from left to right to make a window selection. This selects objects entirely inside the selection rectangle.

2. Drag from right to left to make a crossing selection. Objects inside the rectangle or partially intersected by it are included.

3. Hold Shift while clicking or drawing a selection area to add individual objects to the selection.

4. Hold Ctrl (CMD on Mac) while clicking or drawing an area to remove selected objects from the selection.

This distinction determines whether, for example, you select only lines entirely within a sheet area or capture every element that touches wall or furniture geometry. Window selection reduces the chance of accidentally including nearby objects, while crossing selection makes it easier to gather elements that are only partially visible in a larger area.

Use the following tool when you need to set rectangular selection behavior through command options:

SelRectangular

In Rhino 8, this command is listed under Select › Edit › Select Objects › Area and Volume Select › Rectangular. The documentation lists Window, Crossing, InvertWindow, and InvertCrossing as SelectionMode options. The SelectThroughObjects option also determines whether objects or sub-objects that are behind other geometry and not visible can be selected. When selecting in a dense model, check whether hidden elements should be included.

2. Try lasso and brush selection for irregular areas

When a rectangular boundary would also include unwanted objects, freeform selection tools can be more targeted. Lasso selects objects inside an irregular shape drawn in the viewport. You can use SelectionMode to set window or crossing behavior instead of the default, and inverted selection options are also available. Use Undo to remove the last point while drawing the lasso. Objects that extend beyond the viewport but remain inside the selection boundary can also be selected.

Start the lasso command:

Lasso

Brush selection lets you gather objects by dragging the cursor like a thick line. It uses crossing selection by default, selecting objects touched by the brush stroke. Brush width can be set in pixels. Holding Shift and moving the cursor up or down changes the brush size while you work. When RealTimeSelection is enabled, objects are selected as the brush touches them; when disabled, the selection is applied when the command ends.

SelBrush

A separate brush tool is available for working with control points and mesh vertices:

SelBrushPoints

The documentation also explains how to remove selected points by brushing with Ctrl held down. Brush selection is especially useful for isolating a specific area among many elements that appear close together. However, if the brush is too wide, it may include unwanted nearby objects.

3. Use closed-curve boundaries and sub-object selection

If you need to use an existing closed curve as the selection boundary, use boundary selection:

SelBoundary

This tool can select objects inside or intersected by a closed, view-based curve boundary. With the Precise option set to Yes, selection uses a double-precision floating-point test against the on-screen boundary; if any part of an object is even slightly outside it, the object may be excluded. With the option set to No, a bitmap selection mask is used, creating a tolerance of about half a pixel around the boundary. This can affect whether some objects that appear to be inside the boundary on screen are included.

You can also select faces, edges, or control points rather than entire objects. Many commands allow sub-object selection either before they start (pre-select) or while they are running (post-select). To select sub-objects with the mouse, hold Ctrl and Shift while clicking or drawing a selection area. Clicking or drawing an area with Ctrl removes sub-object selections. Selection filters in the command line can focus on the desired object or sub-object type after a command starts. The documentation lists filters such as crv for curves, edge for edges, srf for surfaces, and face for mesh or SubD faces.

Keep the limitations of blocks in mind: you can select all the objects inside a block, but you cannot select their faces and edges. Objects and sub-objects inside nested blocks also cannot be selected. So if you can’t edit an element, it may be helpful to check whether it belongs to a block before trying a different selection method.

4. Filter architectural models by type and properties

Selection tools aren’t limited to drawing areas on screen. Rhino 8’s documentation lists commands for selecting by properties such as layer, object name, color, render color, material name, and object type. For example, use this command to select all objects on a particular layer:

SelLayer

To select objects with the same render material name:

SelMaterialName

A command is also available for finding geometrically identical objects:

SelDup

These methods help you select building elements organized by layer or surfaces that share a material before making bulk edits to an architectural model. Use the Ctrl+A shortcut to select all objects and Esc to clear the selection. The SelSmall command, which selects objects below a certain size, is listed in the documentation under Select › Edit › Select Objects › Area and Volume Select › Small Objects.

Common mistakes

• Confusing left-to-right and right-to-left selection behavior: the first selects only objects entirely inside the boundary, while the second also selects objects that partially intersect it.

• Working without checking brush width and selection mode: objects outside the intended area may be included.

• Assuming the first click selects the right object when several objects overlap on screen. If a selection menu appears, you can choose an object from the list, cycle through the options with the mouse wheel, and confirm with a right-click.

• Trying to select faces or edges inside a block. According to the documentation, only entire objects can be selected in blocks.

In architecture, interior design, and archviz workflows, choosing the right selection method makes it easier to edit different parts of a model in batches and isolate elements with similar properties. In dense scenes, it can be practical to switch between window, crossing, and lasso selection based on the area you’re working in, and use Selection Filters when needed. This guide is limited to the tools in Rhino 8’s official documentation; it does not specify hardware requirements or licensing conditions.