Here is a very basic CAD terminology tutorial.
There is often confusion or misunderstanding concerning the DWG terminology of thickness, polyline width, pen width and lineweight.
And what is linewidth?
This is probably due to lack of information and poor naming convention.
In this post, I am making an attempt to explain each term and clear the confusion.
For starters, linewidth does not exist in the DWG world. Do not use it if you want to be politically correct in the CAD world!!
There is no such property or command, it is unclear if someone saying linewidth refers to lineweight or polyline width or pen width.
- Thickness is a poorly named property that all DWG entities have. It defines a height for an entity, still the property is misleadingly named thickness. E.g. a circle with a thickness > 0 becomes a hollow cylinder. This thickness is a geometrical property of the entity, not merely a way of displaying the entity. It will show up in a print, depending on the view direction: a hollow cylinder seen from the top is still a circle...
- Polyline width: LWpolylines can be assigned a (constant) width. Like thickness, this is a geometrical property of the entity. If you scale the polyline, the width will scale accordingly. The width will always be visible in the display, it cannot be switched off like lineweight (see below). Old style and 3d polylines can have varying width, i.e. the width of an edge can increase or decrease from vertex to vertex. If a polyline has a width >0, the pen width is not applied when plotting, instead the polyline width will be used.
- Pen width is used only in print preview and print. Entities that have no intrinsic width (width = 0) and polylines with width = 0, get a width in the plot controlled by their color.
In AutoCAD entities can get styles independent of their color, but this does not exist in Bricscad.
- Lineweight is an AutoCAD display property. It can be assigned to individual entities or to an entire layer.
The system variable LWDISPLAY controls if lines are displayed with or without taking the lineweight property into account. On the display, it's not always easy to distinguish lineweight from polyline width. Switching LWDISPLAY off makes it clear. Optionally, the lineweight property can be used to control pen widths in the plot.
(Acknowledgements: Some inputs taken from www.bricsys.com knowledge-base articles)
Reproduced with permission on http://blog.bricsys.com .
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