Part VII: Working with Specialized Functionality
these, the binaries are smaller, but the text files have WordPad readable and editable
headers that can be useful in various situations, such as correcting units or part scaling,
as well as telling what the parent CAD program was.- STEP (AP 214 or AP 203; Standard for the Exchange of Product model data). The AP
stands for application protocol. Most mechanical CAD programs use these two protocols,
which were developed for automotive and configuration controlled design (read more at
http://www.steptools.com/library/standard/step_2.html)..) - ACIS (named for the initials of the three people and one company who created the
standard: Alan, Charles, Ian, and Spatial). ACIS creates *.sat files. - .VDAFS, .VDA (Verband der Automobilindustrie Flächenschnittstelle). A German
automotive geometry transfer format. - IGES (Integrated Geometry Exchange Standard; pronounced eye-jess). Because of the
age and lack of clear definition in the IGES format, there is little that is truly standard
about it any more, and many geometry creation software packages export data that
SolidWorks cannot read correctly. While this format is an old standby for old timers, it is
one you probably want to avoid unless you are getting data from someone you know will
give you something usable.
Another advantage of the Parasolid data is that SolidWorks reads it so quickly. A large IGES or STEP
file can take minutes to read in, where SolidWorks can read equivalent Parasolid data in a couple of
seconds. Once the data is read into SolidWorks, it should all be the same, with no difference between
data from Parasolid and any other source, because it is all converted to Parasolid to be stored inside
the SolidWorks file; but because it’s now all Parasolid, you save time on the initial read.Whether or not the data you receive is of value to you depends in part on what you want to do
with it. If your data only has to be a visual representation, and not a CAD-accurate NURBS (Non
Uniform Rational B Spline) model, you may be able to accept a wider range of data types. If you
are looking for manufacturing quality data, some formats are simply not worth your time to deal
with. These file types are mesh data that SolidWorks can read and are useful for visual data, but
useless for clean NURBS data:l (^) .stl. Stereolithography, typically used for rapid prototypes
l .vrml. Virtual reality markup language, typically used for games, an old format that
allowed color to be transmitted with the mesh geometry
l .cgr. Catia graphics
Converting point cloud data
One of the most common import questions is how to import data from file formats such as .obj
or *.3ds, among others. These file types are mesh files, which means they are simply point cloud
data. SolidWorks and most other CAD programs create data that is based on NURBS data, where
the surfaces are represented by very accurate mathematics. Mesh data is represented by points in
space, which is much faster to work with because it is similar to the data used by graphics cards