What is Metrology Part 19 – Moire Effect in 3D Printing

Share this Article

Moire Effect

Errors are abundant when measuring objects, and we have continually come across this within our series of articles. Image processing in 2 dimensions is vital for transforming images into a 3D structure. This includes extruding a 2D image into 3D as well as stitching 2D images to create a 3D image. Today we will learn about an effect in photography that many of us notice, but are not aware of its terminology. We will also look into how this affects metrology and, subsequently, 3D printing.

The Moire Effect refers to a pattern that is created in images occasionally. A moire pattern is a large in magnitude interference pattern. This can be produced with an opaque pattern that has transparent gaps overlaid within it. To see a large display of the moire interference pattern, two patterns cannot be identical in nature. The patterns have to be rotated or have a slightly different pitch. Overall it is a pretty trippy visual and it messes with our typical human perception in a variety of ways.

Moire Effect 3D Printing

Constructing 3D images from 2D images is a difficult problem. An object that is 3D scanned is vulnerable to the moire effect. When doing a 3D print, the moire effect arises when you notice zebra like stripes on the surface of a print. To stop this it is critical to have great image processing on the 2D level. It seems as though it is nearly impossible to make a roughly perfect 3D image because of the impossibility of creating a perfect 2D image. This is okay, but we are still trying to attain the highest precision possible.

There is a lot of interesting math behind this effect as well. The essence of the moiré effect is the (mainly visual) perception of a distinctly different third pattern which is caused by inexact superimposition of two similar patterns. The mathematical representation of these patterns is not trivially obtained and can seem somewhat arbitrary. In this section we shall give a mathematical example of two parallel patterns whose superimposition forms a moiré pattern, and show one way (of many possible ways) these patterns and the moiré effect can be rendered mathematically.

{\displaystyle {\begin{aligned}f_{1}&={\frac {1+\sin(k_{1}x)}{2}}\\[4pt]f_{2}&={\frac {1+\sin(k_{2}x)}{2}}\end{aligned}}}

Moire Effect Mathematics

The visibility of these patterns is dependent on the medium or substrate in which they appear, and these may be opaque (as for example on paper) or transparent (as for example in plastic film). For purposes of discussion we shall assume the two primary patterns are each printed in greyscale ink on a white sheet, where the opacity (e.g., shade of grey) of the “printed” part is given by a value between 0 (white) and 1 (black) inclusive, with 1/2 representing neutral grey. Any value less than 0 or greater than 1 using this grey scale is essentially “unprintable”.

Moire Effect Background

When is the Moire Effect most prevalent? A terminology that is important to understand within metrology is strain measurement. Strain is a measure of the deformation of a body due to a force being applied to it. Strain is also the mathematical change in dimension of a body when a force is applied. Thus, strain measurement is focused on document the changes within dimension based on force applications. This is great when we want to measure deformations, but not for when we want to remove the possibility of them occurring through a 3D print. There are image scanners that have a descreen filter. These filters typically remove Moire-pattern artifacts. These are produced when scanning halftone images to produce digital images.

In conclusion, the Moire Effect as an interesting visual effect that occurs within the 2D realm and it readily affects the 3D world. With metrology technology, it is one of the various phenomena that can interfere with a high precision scan of an object.


Share this Article

Recent News

Boeing 777x Takes First Flight with over 600 3D-Printed Parts

ABB Robotics Adds 3D Printing to RobotStudio Software


3D Design

3D Printed Art

3D Printed Food

3D Printed Guns

You May Also Like

Generative Design, Digital Twin, WAAM 3D Printing Used to Optimize Industrial Robot Arm

3D printing specialist MX3D has been working on a metal AM technology to create large items, such as bicycles and bridges, using robots. Now, the Dutch startup has partnered up...

Siemens and CEAD Develop Hybrid 3D Printing Robotic Arm

3D printing with continuous reinforcement fibers, like carbon fiber, is just now starting to come into its own, with numerous startups developing their own unique approaches to the concept. Their...

3D Print the New Youbionic Human Arm at Home or Through a Service

Youbionic, founded in 2015, has recently released its new Human Arm. The wildly creative Italian tech startup is on a mission to accentuate already sophisticated technology around the world, while...

Developing 3D Printed Soft Actuators for Robotic Arms

As 3D printing and electronics continue to advance—along with robotics—soft actuators are becoming a great subject of study, as thesis student Hong Fai Lau outlines in the recently published ‘3D-Printed...


View our broad assortment of in house and third party products.

Services & Data

Subscribe To Our Newsletter

Subscribe To Our Newsletter

Join our mailing list to receive the latest news and updates from our 3DPrint.com.

You have Successfully Subscribed!