Model Railroading > 3D Printer (Part 3) – Anti-Aliasing, and why I like it

This is Part 3 of a series on my recent experience with an Anycubic “Photon S” 3D printer.  (Part 1 and 2 were posted earlier.)
 
The term "Anti-Aliasing" came up several times while watching videos or reading about features, so I wanted to understand it.  It is basically a way to smooth-out the layer lines, which is a VERY good thing.  

Layer lines are particularly apparent on sloped or curved surfaces.  The most difficult part to produce is a sphere.  The dreaded stair-step appearance is especially obvious in miniature parts.  The slicer software makes a determination as to whether material will be deposited or not, based on the 3D model.  Imagine trying to represent a circle with a bunch of squares.  The smaller the squares, the more accurate the image.  However, there will still be some jagged edges upon close inspection.  What if the squares could be trimmed into triangles, and the triangles could be a 45-degree diagonal, or a thin sliver?  Now the jagged edges would be smoothed-out, because the transitions are not abrupt.  Similarly, the slicing software no longer thinks in terms of full squares, but instead can print a portion of a square.  

An "alias" is a fake identity.  The printer presents you with a part and says "here is a sphere".  You take a look a it and think, "No it isn't.  It is a bunch of layers trying to look like a sphere.  It is fake."  It is an alias of a sphere.  You know what a true sphere looks like, and this is close, but not the real deal.  However, combine thin slices with Anti-Aliasing, and this part is the result:
 
 



Edited 5 time(s). Last edit at 01/25/20 00:41 by tmotor.

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That sphere (placed on a quarter for size reference) is pretty much free of layer lines.  The Photon Workshop slicing software has improved Anti-Aliasing because it samples more points to determine the smoothest transition between layers.  It ranges from 2 to 8 sample points.  Of course, the more points, the higher the resolution, and smoother the layer lines.  (I keep it pegged at 8.)  The Photon Workshop can slice as thin as 0.05mm, which translates to less than 0.002" !   Combine this with Anti-Aliasing, and the layer lines are significantly reduced.

BTW, the little bits clinging to the side of the sphere is excess resin that I did not remove completely when cleaning the part.  When that excess resin cured, it became permanently bonded to the part.  The resin is clear, and hard to see against a translucent part that is the same color.  To resolve this, I now use an ultrasonic cleaner.
 
Of course, the penalty for very thin layers is it can take hours to print a part.  However, if it produces a more accurate part, I will accept the long print times.
 
The other reason for layer lines can be slop in the vertical (Z) direction.  If the printer does not keep the part properly located between layers, one layer will be offset from the other.  The slicer software did its job of creating a smooth part, but the printer is not "stacking" the layers properly.  A Photon owner retrofitted his printer with a pair of aftermarket linear rails which improved the accuracy.  Other Photon users were impressed and wanted to do the same, so he offered a kit for other Photon owners to modify their printers as well.  The folks at Anycubic saw that, liked the idea, and the Photon S was born.  
 
 



Edited 9 time(s). Last edit at 01/22/20 17:05 by tmotor.

Sanskrit has never been more eloquently phrased.

Based on what I have known about anti-aliasing in computer graphics, it makes total sense how it would be a good thing on 3D printing.

Thanks for this very interesting series.

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