An End To The Dreaded STL Format?

Experiments are underway to 3D print without using STL, the standard meat and potato file format used by 3D printers worldwide. How can this be? The folks at the RepRap project are trying to use a different approach using CSG format. 

 

Ok, let's back up a bit; there are too many acronyms fling around here. STL is an old file format used to store a digital representation of a 3D object. Under the covers it's simply a gigantically long list of tiny triangles that overlay the intended shape. By having a sufficient number of tiny triangles, you can easily approximate the desired shape. 

 

CSG is different. It represents a 3D object by combining a collection of so-called "primitive objects". These may be spheres, cubes, or other simple shapes. Complex combinations of them can also represent arbitrary shapes. 

 

So now you're wondering why change formats? The answer is that STL can very easily introduce incorrect models. Imagine a complete set of triangles surrounding your object. Then remove one of the triangles, creating a "hole" in the model. It's now an incorrect and unprintable 3D model, because the presence of the hole causes problems when translating the shape into 3D printer instructions. 

 

CSG doesn't have such issues because it cannot possibly introduce holes, because all CSG models are composed of primitive shapes that have no holes. Adoption of CSG could eliminate this common problem. 

 

But it's not that simple, as use of CSG is just an experiment at this stage. Building robust CSG interpreters in all 3D printer software is a big deal and likely won't happen for a while. 

 

Via RepRap and Wikipedia

Waiting For AMF

Some months ago (March actually) we wrote about a new file format for additive manufacturing that had been approved after long discussion: AMF, the Additive Manufacturing Format. 

 

This new format included a variety of key features to dramatically improve the information content found in 3D models. Meta data, materials, colors, textures and more were all included. 3D print operators began to drool all over. 

 

On June 17th of this year, AMF leader Prof. Hod Lipson announced:  

 

The AMF fomat has been officially approved by ASTM and will be published shortly as ASTM F2915. I have created a wikipedia entry describing key aspects. Please feel free to edit. 

  

But here we are several months later and as far as we can tell, there hasn't been moves by the 3D modeling tool makers to adopt AMF, even as a test. When they do we'll gain a huge step forward in the software side of the 3D printing equation. Perhaps these vendors have secret internal projects underway and we'll see the results of their work only later on. 

 

Does anyone know of AMF adoption by any tools yet? 

 

Via Wikipedia, ASTM and AMFF

MiniMagics2 Released

Materialise has released a new version of their MiniMagics software, which is used for management of STL files. What can it do? Here's a short list:

 

• Import and save .STL, .magics or .mgx files
• Compress STL files up to factor 20
• View parts and rotate, pan or zoom
• Detect bad edges and flipped triangles
• Make a section
• Request part information, such as XYZ measurements, volume, surface area or number of bad edges
• Measure parts
• Add text annotations
• Create a print-out of parts 

 

The new version includes features to enable more precise measurements using points, circles and planes, additional viewing options and a "silent server installation option" for sites with locked-down computers. 

Did we say that this software is free (with registration)? It's available in English, German and Japanese versions, but only runs on Windows platforms.

 

Via Materialise (Hat tip to Luke)

.STL Overview

There's a terrific overview of .STL and in fact the modelling and 3D printing process available at InstaTuts. It takes you through a simple explanation of how .STL works and how it is produced by modeling software. Eventually the model (a boxer, pictured) is sent to a Dimension SST 3D Printer for production. 

Via InstaTuts

Replacing .STL

We wrote on the problems with the prehistoric .STL format the other week, and bumped into a potential replacement: GTS. It's an open source project:

GTS stands for the GNU Triangulated Surface Library. It is an Open Source Free Software Library intended to provide a set of useful functions to deal with 3D surfaces meshed with interconnected triangles. The source code is available free of charge under the Free Software LGPL license.

The code is written entirely in C with an object-oriented approach based mostly on the design of GTK+. Careful attention is paid to performance related issues as the initial goal of GTS is to provide a simple and efficient library to scientists dealing with 3D computational surface meshes.

The major features of GTS are:

• Object oriented structure
• Delaunay triangulations
• Robust geometric predicates
• Wide variety of surface operations
• Multiresolution models
• Continuous level of detail
• Collision/Intersection capability
• Graph operations
• Metric operations
• Fast rendering

As with any open source project, you are welcome to assist its development.

Via GTS@Sourceforge (Hat tip to Jordan Miller)

.STL To Be Replaced?

RapidToday posts an interesting interview with Hod Lipson, chair of the ASTM Committee on Additive Manufacturing Standards's task force on file formats. The topic: .STL.

You ask what's wrong with .STL? Lots, it turns out. The 1987 vintage standard is so old you could legally buy it a beer in most states. As RapidToday points out, an entire industry has emerged simply to fix broken .STL files. Worse, the standard is so deficient that some printer manufacturers have invented their own proprietary standards or extensions. While these proprietary standards might work for an individual equipment manufacturer, it doesn't help the industry as a whole.

There are obvious deficiencies, such as colors, materials, etc., but according to RapidToday, .STL also needs:

• Better accuracy in representing curved surfaces
• Surface texturing requirements
• Buildability verification (leak patching)
• Inclusion of metadata (e.g. authorship and copyright information)

The STL file format doesn't just lack these capabilities, it also has a few inherent problems: file size is excessive, file security is limited, and it can't detect or fix errors (especially unintended holes) in the part to be built.

What's going to happen next? The task force is conducting a survey to collect input from all stakeholders. You can participate right here.

Via RapidToday

XVL - Now EVEN SMALLER!

Last September we wrote about Lattice Technology's 3D model storage format, XVL, which offers significant (i.e. up to 99%) savings over other formats. Now though, they've gone even farther by announcing XVL v10 that "delivers 2 times more compression of 3D data than the previous XVL formats, along with vastly improved memory consumption and speed of viewing".

No accuracy is lost in XVL v10, even though memory requirements are 25-40% reduced. According to their press release, the key features are:

• Compresses 3D data up to 0.5% of its original size
• Memory usage 25-40% improved
• 3D viewing at least 2 times faster than previous version
• Retains accuracy of the data with no compromise for file size/usability
• Further speed improvements with graphic accelerators deliver even faster viewing and usage of your 3D data, especially with NVIDIA graphics cards
• The industry’s most compressed 3D format

XVL v10 will roll out during the summer of 2009. Oh, and you kinda have to have Lattice's products to use XVL, although they do offer a free viewer.

Via Product Design & Development and Lattice 3D

My Model is Shrinking!

We bumped into Lattice Technology, a company that produces 3D modeling software. What's the big deal? Actually, it's a small deal: Lattice uses a unique storage format, XVL, that offers tremendous space savings over conventional 3D storage formats.

According to Bill Barnes, GM of Lattice:

"Our converters use the industry’s best translation technologies and allow massive 3D data to be compressed, very accurately, into files that are 1% or less of the original size. This makes even the biggest assemblies easily manageable and usable."

Using Lattice's converters, your large files from "every major 3D CAD format" are transformed into XVL and then can use Lattice's 3D tools for visualization, verification, etc.

What does this mean for the 3D print space? We suspect that lightweight file formats will eventually become dominant because they will be easier to deal with. Increasingly complex 3D objects will have increasingly large file sizes. Who would want to download a 1GB pencil holder? The 3D space will be a lot simpler in the future should we adopt more lightweight formats.

Via Lattice Technology