Object types and modeling

Technical discussions
Post Reply
nickz
Site Admin
Posts: 236
Joined: Fri Jul 26, 2013 3:58 am

Object types and modeling

Post by nickz »

Hi
This is a response to http://www.dynoinsight.com/phpBB3/viewt ... f=2&t=2824 which deserves a separate thread

Here is a brief overview of KS section types:

SectionOCC are the BSpline Brep objects http://www.dynoinsight.com/Help/Geom/Ob ... eBRep.aspx based on the Opencascade technology. They are imported/exported via step and iges. It is the main stream for parametric solid/surface modelling. They are great for everything, apart from the fact they are not that simple to modify programmatically. See the Modeling Curves and Shape explorer samples. They can be created at runtime in the program

The next most useful section is the MeshSection. It is basically a mesh. It is imported from stl, vrml ad often from AutoCAD formats. It also can be built programmatically. They are very flexible to model anything, but its modification is not very simple as it is almost a raw set of points. There are operations for scaling, trimming, Boolean operations. Also they can be changed in any way programmatically.

The problem here is that they are not parametric, so they are not built from curves and patches. So you need to know in the program where to move those points. Most often Mesh sections are generated or imported and if any modification is needed they are discarded and new one is created with from different parameters.

The native 3DS section was the first type of object KernelCAD was introduced with. It is useful in some cases, but is little unorthodox. 3DS were created as a simpler alternative in parametric modelling. 3DS are modelled with arc and straight line splines.

For simple case you need to define two or three cross-sections as closed arc/staright line curves to construct a 3DS. The burr model on the DInsight home page is a 3DS. One interesting feature of them is that they can be modelled in cylindrical coordinates using angle and distance to axis. It is useful for modelling spirals or similar axial (the burr) objects

SOR (surface if revolution) is a rotation of an arc/segment spline around z axis. They are pretty simple.

Nick

Post Reply