Regards
Mario
Hod Lipson <hod.l...@cornell.edu> escribió:
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Hi Hod,
BR, .t
--
Furthermore, layers are an inefficient way to describe an object because they do not take advantage of regular geometry. If you wanted to print a 1-inch cube in 16 microns layers, you would need 1500 layers. They are also orientation dependent.
Also, how do you represent graded materials and colors in a layer representation?
It is critical that AMF is process independent, like STL was. I think that there is merit to other representations like Voxel and Function Representation (which should be included in future revisions of AMF), but not Layers.
--hod
Hi -
I don't know about layers - when I send a file, it's just a solid chunk. My
main schtick is that the triangles kill the design. That the tech has to
move in the direction of slicing directly from an IGES, STEP or eventually a
solid file (from Pro/e or Solidworks). Once that happens, we'll be able to
get much closer to consumer-quality, which will be where the real
breakthroughs are.
Scott
--hod
-----Original Message-----
From: st...@googlegroups.com [mailto:st...@googlegroups.com] On Behalf Of Turlif
Sent: Thursday, March 17, 2011 12:10 AM
To: STL 2.0
Subject: Re: ASTM AMF subcommittee ballot successful
Hi Hod,
BR, .t
--
We are in agreement about the slicing might not be right approach as each machine out there has a different requirement for the spacing between each slice. Furthermore future machines might have different requirements as well.
Gonzalo
Gonzalo Martinez
Director, Strategic Research
Office of the CTO
Autodesk, Inc.
1 Market Street, Suite 500
San Francisco, CA 94105
Direct 415 547-2031
Mobile 415 341-7588
-----Original Message-----
From: Hod Lipson [mailto:hod.l...@cornell.edu]
Sent: Thursday, March 17, 2011 2:55 PM
To: st...@googlegroups.com
Cc: tur...@uformiaworld.com; Kulk...@3DSystems.Com; Gonzalo Martinez; dun...@3dsystems.com; summ...@pacbell.net
Subject: Layers are process dependent
In my view, layer based representation is not the most ideal form to represent a 3D model. While the STL format itself is very limiting, a layer based format is further restrictive.
The fundamental difference is as follows:
STL and/or even a native CAD format defines the surface of the object. This could be the a geometric definition, surface property definition, color definition, etc. etc. In all these formats, the external surface is being defined.
A layer based format predominantly defines the "internals" of the object and not the external surface. The external surface is approximately based on the contour profiles and hence it is a 2.5D format at best. 3D Systems already has a SLC format that has been made public a long time ago and used widely in the medical and jewelry industry. It works for them as they native data originates from MRI, CT Scan data and hence adopting the SLC for RP purpose is quite natural. This format does not work well for other mainstream applications due to lack of surface definitions.
Additionally, as data is manipulated, the level of approximations required when managing a surface based format are quite less that those required to make a layer based format work. With these manipulations, the final object being fabricated is moving further and further away from the original definition of the object.
Hence, in my view, an enriched STL format (or a simple surface format) is the right approach.
Rajeev Kulkarni
VP of Global R&D
3D Systems
As an example, let me briefly describe a recent project aimed at
producing brain phantoms (models for scanner calibration) that needed to
be fabricated with radioactive source material selectively deposited
throughout the interior in a manner that would match up with
measurements of patients at various stages of Alzheimer's. A standard 3D
printer suffices to do this job, but not using the standard software and
STL files. What is required is the ability to print a stack of images,
and my colleague managed to create a hack that made this possible. Other
than using radioactive ink (which we probably do not want everyone
doing), this seems like the sort of thing we should be looking to
support without the necessity of hacking the system.
Finally, let me address the general issue of a layered object
description. The layers in the description need not be tied directly to
the fabrication layers, so supporting a layered description should not
impose any limitation on fabrication approaches as long as there are
tools available for determining the properties needed for slicing,
support generation, or whatever other functions are required. Also, if
you think in terms of implicit or function-based models, a layered
description (e.g. a model based on an image stack) need not be limited
to representing 2.5D. Appropriate use of simple interpolants enables
full 3D modeling, and the fabricated part need be no further from the
original model than in the traditional approach using external surface
models and/or STL files. In fact, we have seen cases where the
fabricated part quality is actually enhanced by avoiding unnecessary
triangulation.
Duane Storti
Mechanical Engineering
University of Washington-Seattle
Co-Director Solheim Rapid Manufacturing lab
On 3/22/2011 1:28 PM, Kulkarni, Rajeev wrote:
> All,
>
> In my view, layer based representation is not the most ideal form to represent a 3D model. While the STL format itself is very limiting, a layer based format is further restrictive.
>
> The fundamental difference is as follows:
>
> STL and/or even a native CAD format defines the surface of the object. This could be the a geometric definition, surface property definition, color definition, etc. etc. In all these formats, the external surface is being defined.
>
> A layer based format predominantly defines the "internals" of the object and not the external surface. The external surface is approximately based on the contour profiles and hence it is a 2.5D format at best. 3D Systems already has a SLC format that has been made public a long time ago and used widely in the medical and jewelry industry. It works for them as they native data originates from MRI, CT Scan data and hence adopting the SLC for RP purpose is quite natural. This format does not work well for other mainstream applications due to lack of surface definitions.
>
> Additionally, as data is manipulated, the level of approximations required when managing a surface based format are quite less that those required to make a layer based format work. With these manipulations, the final object being fabricated is moving further and further away from the original definition of the object.
>
> Hence, in my view, an enriched STL format (or a simple surface format) is the right approach.
>
> Rajeev Kulkarni
> VP of Global R&D
> 3D Systems
>
>
>
>
> -----Original Message-----
> From: Jenny Buck [mailto:jebu...@yahoo.com]
> Sent: Thursday, March 17, 2011 9:09 PM
> To: st...@googlegroups.com; 'Hod Lipson'
> Cc: tur...@uformiaworld.com; Kulkarni, Rajeev; Dunne, Patrick; summ...@pacbell.net
> Subject: RE: Layers are process dependent
>
> I need more info, but yes I'm leaning the same direction. As noted, my consolidation& interpretation of potential options over the past 24 hours had its issues as a non-software person. We still have a serious problem at the design output side, though, that we aren't addressing with this standard yet. I still feel it's crucial we generate a solid aim as to how we're tackling that,& that we're a lot surer than we are today that it will actually work.