Best way to model an odd shaped physical object?

Does anyone have any tips on modeling an odd shaped object, say, a clay
model, that someone has shaped by hand.

For example, some totally random shape made by squishing a ball of clay
into an odd shape.

I'm thinking splines in a bunch of parallel planes with an equal number
of points, and lofting between them.

I'll take measurements off the model and transfer into 2D sketches.

Any other ideas?

I don't have a 3D scanner, etc., so let's bypass that option for now...

Thanks!

 

Personally I'd use something other than SW to do it like Rhino which is
actually made for stuff like that.

Short of that, the parallel plane bit will only get you so far, because
at some point you will need to cap off the ends without making them look
like caps. Ed Eaton several years back made a simple model called
"putty ball" or something like that with splines on perpendicular planes
where the splines all met at a central axis and then did a closed loft.
This approach would work for something fairly simple like the dreaded
"amorphous blob", but if the part has any detail, you will need to
combine with other techniques.

If you can identify faces or areas you can create using a particular
technique, that might be the best place to start. For example, sketch
out the part or mark up on your physical lump of clay faces that you
think you can create using lofts. Don't try to build the whole thing in
one whack. Don't be afraid to overbuild to get the right face shape and
then trim back to get the right boundary. This can be difficult if you
don't have any identifiable edges.

There is no "easy button" for things like this, and SW isn't
particularly well suited to it.

matt

 

James.

Go to http://www.mikejwilson.com and downdload the Scooby Doo model. It was
done 100% with surfacing, and will give you some ideas.

Regards

Mark

 

The problem is that most of the commands are built to create as smooth
a surface as possible. I have had good luck working with photographic
references. A lot of other progs are more suited to this task.

Possibly:
Photograph the model from a Lazy Susan style pedestal and overlay all
those images on the Front Plane (or plane normal to camera view), and
trace the outlines with splines on construction planes corresponding to
the angle at which the photograph was taken. Then loft

If you are not particular about the shape use a fill surface or two
with 4 or 5 constraint curves. That should be enough to wig the
algorithm into creating a very rough surface

 

Hi James,

have a look at:

http://www.solidworks.com/swexpress/pages/sep05/FN_CosmicBlobs.html

http://www.cosmicblobs.com/

There is a free available demo.
The use of this software seems to be very clay-like (check tutorial videos)

Also have a look at the thread "CosmicBlob for kids" Ther are already some
SW users who made experiences with this software.

Good luck

Jo

 

If SWX is your only available software in addition to the other
suggestions you might start by searching for Ed Eaton's Curvy Stuff
tutorials at Dimonte Group.

Here are some step-by-step tutorials for getting started.
http://home.pct.edu/~jmather/content/DSG322/solidworks_surface_tutorials.htm

 

Not necessarily the cheapest, but by far the easiest would be to send the
clay blob out to a vendor with a digitizing arm and get a cloud of points
back. Import that model into SW. Depending on what your neeeds are, you
might be done at that point. If you need to refine the blob (perhaps for
manufacturing reasons), you can then create individual surfaces that follow
the contours of the imported blob. Doing it this way eliminates the
annoying (and error prone) measurement step

A lower tech method that will also work (if you can destroy the blob to
capture it):
Put the blob onto a scanner and take an image. Slice away a section (.100"
say), take another scan, repeat until the blob is gone.
Import the images onto planes spaces at your slice distances, and trace the
edges of each slice. You've now got a set of guide curves that you can use
to make your model

 

On a side note, an outside service would probably opt to digitize it
using a laser scanner instead of the point by point physical contact
type of digitizing. I believe there are services that will even supply
you with a solid model if you so choose. It would most likely be just
an iges or step file without a feature tree.