surface modeling and solid modeling

[yogesh]

hello,

how do solid modeler and surface modeler algorithmically differ??
i.e what i perceived so far after reading about them is
1)the surface modeler can draw surfaces so that you can tell whether a
point is on it or not and
2)you can draw solids so that you can tell whether a point is
inside,outside or on the solid or not??

now algorithmically the solid modeler just adds the point normal
information and compares it with the surface normals..so does it mean
that the developer of surface modeler are lazy to put just a point
normal information and make their modeler as solid modeler???

regds,
yogesh

 

[Raymond]

Hi,

Generally speaking, I think solid model is better than surface model.
For example, solid has weight, you can know a part's weight before any
prototype or product be made. You can do FEA strentgh analysis and
know if it is strong enough for solid. These can not be achieved with
surface model. However, in the modeling process, surface sometimes is
necessary.

Regards,

Raymond

 

[Raymond]

We used to do this all the time with closed surface models.


That was often done as well.
Solids is fairly new, using kernels.
FEM and mass properties are not. All available back in the days of
CADDS-III (and probably other systems as well), more than two decades ago.

I know closed surface model can be regarded as solid in a meaning, and
SolidWorks just do this when it open a closed surface model created by
Rhino etc.. My opinion is just appealing industrial designer to give
us, the structure designer and mold designer, solid model, or closed
surface model with high modelling quality. I hate to open a surface
model with bad modelling quality, it is sometimes too difficult to
convert it into solid and do further design to it.

If you want to modify the model, you will find that solid is much
better than surface. For example, if you want to make a sinked holes
somewhere, it is much quicker using solid than surface.

For molds designing, solid is much better than surface. You can use
boolean fuction with solid model to form cavities.

Raymond