In physics and mathematics, the dimension of a space or object is informally defined as the minimum number ofcoordinates needed to specify any point within it.[1][2] Thus a line has a dimension of one because only one coordinate is needed to specify a point on it (for example, the point at 5 on a number line). A surface such as a plane or the surface of acylinder or sphere has a dimension of two because two coordinates are needed to specify a point on it (for example, to locate a point on the surface of a sphere you need both its latitude and its longitude). The inside of a cube, a cylinder or a sphere is three-dimensional because three coordinates are needed to locate a point within these spaces.
In physical terms, dimension refers to the constituent structure of all space (cf. volume) and its position in time (perceived as a scalar dimension along the t-axis), as well as the spatial constitution of objects within—structures that correlate with both particle and field conceptions, interact according to relative properties of mass—and are fundamentally mathematical in description. These, or other axes, may be referenced to uniquely identify a point or structure in its attitude and relationship to other objects and occurrences. Physical theories that incorporate time, such as general relativity, are said to work in 4-dimensional "spacetime", (defined as a Minkowski space). Modern theories tend to be "higher-dimensional" including quantum field and string theories. The state-space of quantum mechanics is an infinite-dimensional function space.
The concept of dimension is not restricted to physical objects. High-dimensional spaces occur in mathematics and the sciences for many reasons, frequently as configuration spaces such as in Lagrangian or Hamiltonian mechanics; these are abstract spaces, independent of the physical space we live in.
A reference dimension is a dimension on an engineering drawing provided for information only.[1] Reference dimensions are provided for a variety of reasons and are often an accumulation of other dimensions that are defined elsewhere[2] (e.g. on the drawing or other related documentation). These dimensions may also be used for convenience to identify a single dimension that is specified elsewhere (e.g. on a different drawing sheet).
Reference dimensions are not intended to be used directly to define the geometry of an object. Reference dimensions do not normally govern manufacturing operations (such as machining) in any way and, therefore, do not typically include a dimensional tolerance (though a tolerance may be provided if such information is deemed helpful). Consequently, reference dimensions are also not subject to dimensional inspection under normal circumstances.[1][2]
Prior to use of modern Computer-Aided Design (CAD) software, reference dimensions were traditionally indicated on a drawing by the abbreviation “REF”[1] written adjacent to the dimension (typically to the right or underneath the dimension). However, with the assistance of modern CAD software, the abbreviation “REF” has often been replaced with the use of parentheses around the dimension.[1][2] As an example, a distance of 1500 millimeters might be denoted by "(1500 mm)" instead of "1500 mm REF." Although both of these methods of denoting a reference dimension are accepted and still in use today, it is increasingly common to see the use of parentheses instead of the abbreviation “REF” primarily due to widespread use of modern CAD software that makes use of parentheses as the default denotation method whenever reference dimensions are “automatically” created by the software.
A dimension is for size and position (of the designed/modeled shape).
• A
DIMENSION
is a numerical value expressed in appropriate units of measurement and used to define the si ze, location, orientation, form or other geometric characteristics of a part.
• A method of communication to machin ists in the Production facility.
• Different kinds:
– Linear
– Aligned
– Angular

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Dimensions in Drawings
Dimensions in a SolidWorks drawing are associated with the model, and changes in the model are reflected in the drawing. Model Dimensions | Typically, you create dimensions as you create each part feature, then insert those dimensions into the various drawing views. Changing a dimension in the model updates the drawing, and changing an inserted dimension in a drawing changes the model. | Mark for Drawings | You can specify that dimensions marked for drawings be inserted automatically into new drawing views. Go to Tools > Options and in the Document Properties tab, click Detailing. Select Dimensions marked for drawing under Auto insert on view creation. | Reference Dimensions | You can also add dimensions in the drawing document, but these are reference dimensions, and are driven; you cannot edit the value of reference dimensions to change the model. However, the values of reference dimensions change when the model dimensions change. | Standard Dimensions | You can create standard dimensions in drawings, such as dimensions created in a sketch. This includes Smart, Horizontal, and Vertical dimensions. | Rapid Dimension | Use rapid dimensioning to place evenly spaced dimensions. |
Contents
* Formatting Dimensions in Drawings
The dimension palette appears when you insert or select a dimension so you can easily change the dimension's properties and formatting. You can change the tolerance, precision, style, text, and other formatting options in the palette without going to the PropertyManager. * Dimensions Display Options
Right-click a dimension and select Display Options. The choices available depend on the type of dimension and other factors and can include the following: * Hide/Show Annotations
Hide/Show Annotations allows you to toggle the visibility of individual annotations or tables in a drawing. * Highlighting Changed Dimensions * Inserting Dimensions into Drawings
Dimensions in a SolidWorks drawing are associated with the model, and changes in the model are reflected in the drawing. * Dimension Type * Document Properties - Dimensions
You can specify document-level drafting settings for all dimensions. Available for all document types. * Dimension Other PropertyManager
In the Dimension Other PropertyManager, you can specify the display of dimensions. If you select multiple dimensions, only the properties that apply to all the selected dimensions are available. * Dimension Value PropertyManager
In the Dimension Value PropertyManager, you can specify the display of dimensions. If you select multiple dimensions, only the properties that apply to all the selected dimensions are available. * Dimension Precision * Aligning Dimensions and Notes
You can align dimensions and notes in several ways by using inferencing lines, grids, and align tools. * Scan Equal
Scan Equal (Dimensions/Relations toolbar) scans in drawings for sketch lines of equal length or sketch arcs of equal radii. It does not examine model entities. * Rapid Dimension
You can use the rapid dimension manipulator to place dimensions so they are evenly spaced and easier to read. * Autodimension a Drawing
You can use the Autodimension tool to insert reference dimensions into drawing views as baseline, chain, and ordinate dimensions. TheAutodimension tool works similarly in sketches. * DimXpert
DimXpert speeds the process of adding reference dimensions by applying dimensions in drawings so that manufacturing features, such as patterns, slots, and pockets, are fully-defined. * Dimension PropertyManager
Allows you to dimension a drawing with smart or DimXpert dimensioning. * Adding Parallel Dimensions to Drawings * Reference Dimensions
Reference dimensions show measurements of the model, but they do not drive the model and you cannot change their values. However, when you change the model, the reference dimensions update accordingly. * Reference Center of Mass in Drawings
Center of mass is a selectable entity in drawings, and you can reference it to create dimensions. * Using Parentheses on Particular Dimensions * Baseline Dimensions
Baseline dimensions are reference dimensions used in drawings. You cannot change their values or use the values to drive the model. * Ordinate Dimensions
Ordinate dimensions are a set of dimensions measured from a zero ordinate in a drawing or sketch. In drawings, they are reference dimensions and you cannot change their values or use the values to drive the model. * Chamfer Dimensions
You can dimension chamfers in drawings. In addition to the usual dimension display properties, chamfer dimensions have their own options for leader display, text display, and X display. * Tolerance and Precision * Moving and Copying Dimensions
Once dimensions are displayed in a drawing, you can move them within a view or to another view. When you drag a dimension from one place to another, the dimension reattaches to the model, as appropriate. You can only move or copy dimensions to a view where the orientation is appropriate for that dimension. * Modify Dimension
You can change a dimension in a part, sketch, assembly, or drawing in the Modify dialog box. * Deleting Dimensions * Dimension Palette
The dimension palette appears when you insert or select a dimension so you can easily change the dimension's properties and formatting. You can change the tolerance, precision, style, text, and other formatting options in the palette without going to the PropertyManager. * Dimension Extension Lines
You can change the default attachment point of dimension extension lines , slant the extension lines, flip the direction of a leader, and drag extension lines between the center, minimum, and maximum attachment points of arcs and circles. * Dimension Leaders/Text
By default, the display of dimension text with respect to the leaders follows the selected dimensioning standard. You can override the default display. * Example: Dimension Scheme Types * Dimensioning to Midpoints