Before I begin: Congratulations to my friends at Clockwork Publishing, Modiphius Entertainment and Chronicle City...
The Space 1889 Kickstarter is roaring to its conclusion with funding achieved for all sorts of great stuff, including miniatures!
Achtung Cthulhu is an ENNIE award winner for its 'Three Kings' adventure supplement, and the team are having a great time at Gen Con!
Last time, I talked through some of the materials and processes involved in printing a virtual model into a physical reality. However, regardless of what print method you use, the printer will need the model in a data format it can use. This blog entry is going to briefly summarise how this works and why it's not as easy as you'd hope!
The most commonly accepted file format for 3D printing is the STL (standard tessellation language) file. This format converts a 3D editable mesh (OBJ, MAX, DWG, etc) into a non-editable set of geometry data that a printer can use to create its print layers. The printer software will take any model and 'slice' it into individual pieces that each represent one print layer. If you're familiar with card 'sculpture puzzles' then you will appreciate the process.
The Space 1889 Kickstarter is roaring to its conclusion with funding achieved for all sorts of great stuff, including miniatures!
Achtung Cthulhu is an ENNIE award winner for its 'Three Kings' adventure supplement, and the team are having a great time at Gen Con!
Last time, I talked through some of the materials and processes involved in printing a virtual model into a physical reality. However, regardless of what print method you use, the printer will need the model in a data format it can use. This blog entry is going to briefly summarise how this works and why it's not as easy as you'd hope!
The most commonly accepted file format for 3D printing is the STL (standard tessellation language) file. This format converts a 3D editable mesh (OBJ, MAX, DWG, etc) into a non-editable set of geometry data that a printer can use to create its print layers. The printer software will take any model and 'slice' it into individual pieces that each represent one print layer. If you're familiar with card 'sculpture puzzles' then you will appreciate the process.
    | In this example of everyone's favourite movie character of all time, layers of cardboard stack up to create the illusion of a 3D object. The 3D process for printing is exactly the same, only the layers are many times thinner and finer. It is because of this approach that 'support' material is needed- if part of a model connects to the whole at a point that prints later than the rest of that part, without a support, it would be disconnected and float away from the print. However, before that stage is reached, there are a number of issues that have to be checked to create a printable STL. The big three are:
Here is a gun OBJ from a 3D model online store. Perfect for a video game model, it will not work for printing. Although it looks like a single object, it contains many 'shells' or parts. The next image shows some of the many separate shells that form the gun- over 100 in total and some are tiny. The 3D printer will attempt to treat each as a separate object. Some simple printers can handle this, but anything detailed enough to produce models useable in casting will not cope- leading to a long and expensive process of manually fixing by the printer operator. The third image shows a non manifold cube- some of the faces that form the cube are either missing or inverted (facing inwards). 3D faces have no thickness and only have one side- there is no depth data and the inner sides are not calculated, so only a fully closed shape is physically realistic. This means the object cannot exist 'in the real world' so will not print. The final image, from Gears of War 3 by Epic Games, shows how the detail on this model, like many game models, is created through beautifully crafted textures. This allows the game engine to create detailed models at high framerates. However, none of that texture or detail will print- the flattened wireframe model is the actual figure that will be recreated. |
Although many 3D programmes can export in STL format, they cannot fix these issues themselves.
Some of these issues can be fixed when making the model, which I will talk about next week. Some of them can be fixed after completing the model using 'mesh checking' software such as meshlab, magics or netfabb. These programmes use algorithms to check for inverted or missing faces and holes, and weld together loose shells. They then write the file as the STL the printer needs, from whatever 3D format was imported. They cannot alter the model too much and some of their fixes can be destructive to details, so it is better to prepare the model for printing as it is created. They cannot do anything about detail from textures- this is a sculpting concern!
Prepping a model for print is about more than just the technical hurdles- there are other concerns to do with casting limitations, material limitations of pewter, resin and plastic, and getting a crisp and paintable miniature too!
Next entry, I will look at how I created one of the Acthung Cthulhu miniatures, what decisions I made and how this helps the process. I'll also return to these example images- they have more to reveal! I will also talk about why much of the VFX training and Video Game modelling techniques that are found online can actually hinder the process of creating miniatures!
Thanks for reading!
Some of these issues can be fixed when making the model, which I will talk about next week. Some of them can be fixed after completing the model using 'mesh checking' software such as meshlab, magics or netfabb. These programmes use algorithms to check for inverted or missing faces and holes, and weld together loose shells. They then write the file as the STL the printer needs, from whatever 3D format was imported. They cannot alter the model too much and some of their fixes can be destructive to details, so it is better to prepare the model for printing as it is created. They cannot do anything about detail from textures- this is a sculpting concern!
Prepping a model for print is about more than just the technical hurdles- there are other concerns to do with casting limitations, material limitations of pewter, resin and plastic, and getting a crisp and paintable miniature too!
Next entry, I will look at how I created one of the Acthung Cthulhu miniatures, what decisions I made and how this helps the process. I'll also return to these example images- they have more to reveal! I will also talk about why much of the VFX training and Video Game modelling techniques that are found online can actually hinder the process of creating miniatures!
Thanks for reading!
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