Object snaps

Last updated: 2023-01-04

Total video time: 18:14

Object Snaps are tools built into Civil 3D that help ensure precision when laying out geometry with both basic objects (i.e. Line, Polyline) and smart Civil 3D objects. The idea is that when specifying location during a command, a given Object Snap will force the location to be at the exact specified object point when the command is active and your cursor is within the Object Snap buffer distance. When an Object Snap is ready to take effect, a glyph will appear indicating the type of Object Snap and location of the snap point.
Object Snap Glyph Image Object Snap Glyph Image
Endpoint Extension
Midpoint Insertion
Center Perpendicular
Geometric Center Tangent
Node Nearest
Quadrant Apparent Intersection
Intersection Parallel

Exercise files: acad-data-c3d20.zip

Start with acad-objct-snp-begin.dwg

acad-objct-snp-01.mp4 4:17

Access to settings

There are a few different ways to access Object Snap settings.

  1. Open acad-objct-snp-begin.dwg
  2. Status Bar > Customization
    1. 2D Object Snaps = checked
    2. Press icon to Turn on Object Snaps

  3. Status Bar > Object Snap icon
    1. Right-click on 2D Object Snap icon
    2. Place checkmark to turn on individual Object Snaps

  4. Status Bar > Object Snap icon
    1. Left-click flyout triangle
    2. Observe access to running Object Snaps list
      1. Object Snap Settings...
        1. Drafting Settings dialog box, Object Snap tab

        1. Object Snap On = checked
        2. Select All
        3. Clear All
        4. Midpoint = checked
        5. OK
    3. Ribbon > Home tab > Draw panel > Polyline button
      1. Turn on Midpoint Object Snap
      2. Move cursor over objects
        1. Observe Midpoint glyph appear
        2. esc to deselect
  5. Model space
    1.  Shift+right-click
      1. Osnap Settings...
    2. Observe access to Drafting Settings dialog, Object Snap tab

Introduction to Object Snap use

In this example you will use the Midpoint Snap to move Mtext to the correct location on a title block.

  1. Continue working in acad-intrfc-begin.dwg
  2. Status Bar > Object Snap icon
    1. Right-click
      1. Midpoint = checked
  3. Select "MAINTAINENCE CROSSOVER FOR FREEWAYS" Mtext object
    1. Select insertion point grip
      1. Move cursor near middle of red construction line
      2. Observe Midpoint glyph appear
      3. Left-click

    2. Select red construction line
      1. delete

Start with acad-objct-snp-begin.dwg

acad-objct-snp-02.mp4 3:37

F3 hotkey

A "alias" is essentially a single keystroke shortcut designed to streamline execution of a task or string of tasks. Many hotkeys are programmed and ready for use in Civil 3D. The"F3" key is one powerful hotkey relevant to Object Snap use. You might incorporate this into your typical Object Snap workflow to improve efficiency.

  1. Continue working in acad-objct-snp-begin.dwg
  2. Toggle Object Snaps off: F3
  3. Toggle Object Snaps on: F3
  4. Ribbon > Home tab > Draw panel > Polyline button
    1. Hold F3
    2. Hover over a Line object
    3. Observe that Object Snaps are temporarily suppressed

Object snap cycling

Pressing the tab key allows you to cycle through Object Snaps relevant to a given object as long as those Object Snaps are turned on.

  1. Continue working in acad-objct-snp-begin.dwg
  2. Status Bar > Object Snap icon
    1. Right-click
      1. Endpoint = checked
      2. Midpoint = checked
    2. Verify Object Snaps turned on
  3. Ribbon > Home tab > Draw panel > Polyline button
    1. Hover cursor over middle of EDGE OF PAVED MEDIAN SHOULDER Line
      1. Observe Midpoint glyph appear
      2. tab
      3. tab
      4. tab

System variable: ignore elevation

By default, Civil 3D will apply existing geometry elevation when using Object Snaps and existing geometry to specify location. You can change this behavior so elevation properties are ignored and only location in the X,Y plane are used when "snapping". This is done by resetting the OSNAPZ System Variable. When this is done, the elevation Z=0 will be used for new location specification.

  1. Continue working in acad-objct-snp-begin.dwg
  2. Ribbon > Home tab > Draw panel > Polyline button
    1. Draw a single Polyline
      1. Select Polyline drawn
      2. Properties Palette > Geometry
        1. Set Elevation = 100
        2. esc
  3. Ribbon > Home tab > Draw panel > Polyline button
    1. Use Endpoint Snap to specify location on end of Polyline drawn in 2.A
      1. Select Polyline drawn
      2. Properties Palette > Geometry
        1. Observe Elevation = 100
  4. Command line: OSNAPZ
    1. enter
    2. 1
    3. enter
  5. Ribbon > Home tab > Draw panel > Polyline button
    1. Use Endpoint Snap to specify location on end of Polyline drawn in 2.A
      1. Select Polyline drawn
      2. Properties Palette > Geometry
        1. Observe Elevation = 0
  6. Select previous three Polylines drawn
    1. delete

Temporary overrides

Calling up temporary Object Snap overrides either through the command line or right-click menu allows a "one-time use" override to current Object Snap settings. For example, you could have Endpoint Object Snaps currently on, then use a temporary Midpoint Object Snap override to ignore all Endpoint Snaps and use Midpoint Snaps for the next location specification. Alternatively you might have all running Object Snaps off, then use any temporary Object Snap overrides as you need them for the next location specification. This temporary override workflow avoids the need to open a running Object Snap interface and thus can improve efficiency.

After a command requiring location input is activated, hold Shift key and right-click to open the temporary Object Snap override menu. Choose a one-time use temporary Object Snap override from this list. Continue location specification.

  1. Continue working in acad-objct-snp-begin.dwg
  2. Turn on running Endpoint Object Snap using your method of choice
  3. Ribbon > Home tab > Draw panel > Polyline button
    1.  Shift+Right-click
      1. Midpoint
    2. Left-click first endpoint and then second endpoint of line you want to midpoint snap to.

Start with acad-objct-snp-begin.dwg

acad-objct-snp-03.mp4 4:48

Geometric Center

This Object Snap analyzes any closed area object and snaps to the centroid of that area. The object can be irregularly shaped, but must show as "closed" in the properties palette for the Geometric Center snap to work.

  1. Continue working in acad-objct-snp-begin.dwg
  2. Turn on running Geometric Center Object Snap using your method of choice
  3. Select "6" Mtext at right of drawing extents
    1. Select middle-center Mtext insertion point
      1. Move cursor to hover over adjacent rectangular closed Polyline
      2. Observe Geometric Center glyph appear
      3. Left-click

Quadrant

This Object Snap grabs the location on a Circle, Ellispse or Arc object intersecting with any of the four 2D quadrant lines (i.e. along X or Y axis).

  1. Continue working in acad-objct-snp-begin.dwg
  2. Turn on running Node Object Snap using your method of choice.
    1. Observe the behavior of the Node Object Snap glyph as you hover over different objects.
  3. Turn on running Quadrant Object Snap using your method of choice.
  4. Select Line representing signage in the PLAN VIEW area of drawing extents
    1. M enter
      1. Shift+Right-click
        1. Midpoint
    2. Move cursor near Circle representing sign post in PLAN VIEW area of drawing extents
      1. Observe Quadrant glyph along positive X-axis appear
      2. Left-click

  5. Turn on running Intersection Object Snap using your method of choice.
    1. Observe glyph behavior as you hover over any area of intersecting geometry.

Start with acad-objct-snp-01.dwg

acad-objct-snp-04.mp4 5:32

Extension

The Extension Object Snap will find a point on a projected extension of a drawing object.

  1. Open acad-objct-snp-01.dwg
  2. Turn on running Extension Object Snaps using your method of choice.
  3. Ribbon > Home tab > Draw panel > Polyline button
    1. Move cursor near any arc in PLAN VIEW area of drawing extents
      1. Observe Extension Object Snap glyph appear and that it shows a continuing green extension of the arc as you move outside of the arc.
      2. Left-click
    2. Move cursor near a line and extend along the path of the line past its endpoint and notice the same green extension appear.
    3. esc

Insertion

The Insertion Object Snap will snap to the insertion point of objects such as blocks or text.

  1. Open acad-objct-snp-01.dwg
  2. Turn on running Insertion Object Snaps using your method of choice
  3. Ribbon > Home tab > Draw panel > Polyline button
    1. Move cursor near any block or text in the drawing.
      1. Observe Insertion Object Snap glyph appear at the insertion point of the object.
    2. esc

Perpendicular

The Perpendicular Object Snap will snap perpendicular to any object such as a line or polyline in relation to the object being drawn.

  1. Open acad-objct-snp-01.dwg
  2. Turn on running Perpendicular Object Snaps using your method of choice.
  3. Ribbon > Home tab > Draw panel > Polyline button
    1. Click any point in the drawing.
    2. Hover near any line or other object in the drawing for your second point.
      1. Observe Perpendicular Object Snap glyph appear at the perpendicular point of the other object.
    3. esc

Tangent

The Tangent Object Snap finds the point of tangency on a Circle, Arc, or Ellipse object coming in from any Line or Polyline object.

  1. Open acad-objct-snp-01.dwg
  2. Turn on running Tangent Object Snaps using your method of choice.
  3. Ribbon > Home tab > Draw panel > Create Line
    1. Move cursor near PLAN VIEW area of drawing extents.
      1. Left-click anywhere to place first point.
    2. Move cursor near Circle representing median back of curb in PLAN VIEW area of drawing extents
      1. Observe Tangent Object Snap glyph appear
      2. Left-click to create line tangent to the circle.

Nearest

The Nearest Object Snap will anywhere on an object nearest to where the user clicks.

  1. Open acad-objct-snp-01.dwg
  2. Turn on running Nearest Object Snaps using your method of choice
  3. Ribbon > Home tab > Draw panel > Polyline button
    1. Click any point in the drawing.
    2. Hover near any line or other object in the drawing and observe the Nearest Object Snap glyph appear.
    3. esc

Parallel and Apparent Intersection

Use the Parallel Object Snap to lay out new linear objects while referencing existing linear objects for directional orientation. You will first start the new linear object command (i.e. Line), then hover over the desired linear reference object. This will activate the Parellel Object Snap and you will see a dashed extension line as a preview of your new linear object draw parallel to that existing. Apparent Intersection Object Snap allows a user to snap to where two objects would intersect even if they do not actually connect. This object snap will extrapolate the linework to find the point at which the objects would intersect if they were extended far enough to intersect.

  1. Continue working in acad-objct-snp-01.dwg
  2. Turn on running Enpoint, Apparent Intersection and Parallel Object Snaps using your method of choice
  3. Ribbon > Home tab > Draw panel > Line flyout > Polyline button
    1. Move cursor near upper right of SECTION A-A, CRUSHED AGGREGATE BASE COURSE border Line
      1. Observe Endpoint Object Snap glyph appear
      2. Left-click
    2. Move cursor to hover over adjacent TOPSOIL Line
      1.  Observe Parallel Object Snap glyph appear
    3. Move cursor along path from the new Line starting vertex parallel to TOPSOIL Line
      1. Observe Parallel preview line appear
    4. Move cursor to point of intersection of parallel preview line and existing BOTTOM OF MEDIAN Line.
      1. Observe Apparent Intersection Object Snap glyph appear
      2. Left-click