Just trying to import this STL file into MoI, tried to convert it into DXF, 3DM, STEP format using C4D and Rhino5 trial without success, MoI didn't load anything.

Just to know what I'm doing wrong.

https://drive.google.com/file/d/0BxbefK5ByPzyNkc1R3ZQcEhHR00/view?usp=sharing

.STL is a polygon format

MoI can't import polygon data.
There is not specific polygon modeling tool in MoI either.

From the command reference :

MoI supports reading in curve and surface data from 3DM, IGES, STEP, and SAT files. 2D curves can be opened from PDF and AI files, and curves and drafting entities like lines, circles, and arcs can be opened from DXF files.

(rhino can store polygon in .3dm, but this data will be ignored in MoI)

Any way to convert a polygonal model into one recognized by MoI?

Qui c'è tutto ;)

http://moi3d.com/forum/messages.php?webtag=MOI&msg=6674.1


M

Hi davide,

re:
> Just trying to import this STL file into MoI, tried to convert it into DXF, 3DM, STEP format
> using C4D and Rhino5 trial without success, MoI didn't load anything.
>
> Just to know what I'm doing wrong.

As others wrote above, the problem is that STL is a polygon mesh format - that means the model data in the file is made up of a whole bunch of little flat triangle facet pieces. That is a very different kind of model data than the curves and spline surfaces that MoI works with at modeling time.

It is possible to convert from smooth spline surfaces into triangles by dicing up the large surfaces into little facets which is what MoI will do when you export to STL format. But it is not very easy to try and do the reverse and try to form large smooth surface patches out of already diced up little flat pieces. So that's why there isn't any regular way to import STL facet data into Moi - MoI is not designed to work with that type of data at modeling time, it only deals with that type of data for export.

It is possible in some cases to convert polygon mesh data into spline surfaces, like with Rhino's MeshToNurb command but I would not recommend it for general purpose use because CAD programs like MoI are not really designed to work with models made up of a huge number of little flat pieces that only approximate a curved surface, CAD programs are designed to work with larger actual smooth surfaces.

What is it that you are trying to do with the STL file that you wanted to load into MoI? You will probably need to use a polygon mesh editing program to work on it, not MoI.

Hope this helps explain things - different file formats can represent 3D models in very different ways and programs tend to be focused on working with one particular style of data. STL data is a triangle mesh type of data and so for loading it in usually you need a polygon mesh editing program for that.

- Michael

Thanks all.
It's really clear to me the difference among polygonal and solid modeling in the theory, but never worked on solid modeling sw.
Understood probably the best choice is to have both, need to further evaluate if MoI good as is for modelling is really what we need.

Returning to this topic, we will order tomorrow our first 3d scanner (DAVID SLS3), we received just Saturday our first 3d printer (a new FDM advanced model not yet on the market).

We want start using both together, understood is not immediate but possible using some external programs to import the scan point cloud into MOI, wanted to know how adapt is MOI to model following the resulting mesh as guide.

Growshapes.com states output as obj, stl, or ply, and a hefty price.
What will the file sizes be?
Brian

Hi davide,

re:
> using some external programs to import the scan point cloud into MOI, wanted to know how
> adapt is MOI to model following the resulting mesh as guide.

MoI is not very good at this type of task - it has not been designed to do reverse engineering of mesh data into NURBS solids, that really requires a special dedicated toolset that is pretty different from the toolset used for regular CAD modeling.

You can use MoI for doing 3D printing, but the way you use it is by drawing your object from scratch and then exporting your model to STL format, not by trying to convert scanned data.

There are various specialized programs that are designed to work with point cloud data, you might check out Geomagic , or also look at some of the reverse engineering plugins that run inside of Rhino: http://wiki.mcneel.com/rhino/reverseengineering

But MoI itself is not focused on that type of process.

- Michael

Thanks Michael.
Using MOI3D to draw the solid using the imported mesh (generated from the point cloud) just as a guide make sense?
I'm trying to find a smooth way to approach the problem, since all the other packages I was researching such as Rhino, Geomagic Wrap/Design X or SpaceClaim appear to be a steep start for beginners.

Hi David,

> Using MOI3D to draw the solid using the imported mesh (generated from the
> point cloud) just as a guide make sense?

It's theoetically possible for some cases but there are many situations where it's not very feasible like with areas that the mesh has branching areas.

Reverse engineering just tends to be an overall a complex area which MoI is not specifically equipped or designed to work with.

- Michael