In this instructables, I will describe quickly what the moiré effect is and how to create custom moiré effect animations and use them around the house to make intriguing decorations.

Simply put the moiré effect, in the application I will be describing here, is a way of presenting pictures in such a way that your brain is going to interpret them as an animation. The power of the moiré effect effectively heavily relies on the image processing of your brain.

Well, it is not exactly that simple, as you will see in the rest of this instructables two other things are of paramount importance, first, the careful creation of the design and second the grid (the grid is in a way a pre-filter, your brain is doing the rest of the reconstruction of the animation)

Supplies

black sheet of paper

TOOLS:

Laser cutter

Computer with inkscape

Caliper

Step 1: What Are We Talking About ?

Like a regular camera, to work effectively, the moiré effect needs multiple pictures each with an ”incremental movement”, meaning that the complete animation is broken down into several pictures each with part of the movement. Your brain will bridge the gap between the steps to reconstruct the entire movement.

This last point is a very important aspect of the moiré effect: extremely limited number of pictures in the animation. Indeed, we are physically (in terms of physical space on the page) limited to 4-5 pictures to describe the entire animation. The reason that I choose no more than 5 steps for the animation is that I find the picture too unrecognizable if we add more steps (the windows in the grid are becoming too narrow and distorts the perceived image too much).

Conceptually, we are keeping only a fraction of the image of each steps, meaning that for a 5 step animation, each step, when visible is covered at 80% by the grid ! In addition, the perceived darkness of the picture increases with the number of steps in the animation (picture 80% full black with 5 steps, 83% with 6 steps, etc).

Quick note here, another interesting property of the moiré aspect is that we are removing (in the 5 step animation example) 80% of every step picture and your brain still makes sense of every individual step (that is effectively data compression and reconstruction)! Our brains are so awesome !

The grid is characterized by:

The relative width of the windows vs the width of the blocker (as discussed above)

The absolute width of the windows

The absolute width of the windows should be conceptually chosen only relative to the resolution you want to get out of each of your pictures but should practically alsotake into consideration that the finer the resolution of the grid (thin windows), the harder the manufacturing of said grid.

That was my super short explanation of the moiré effect, you can find quite a lot of further explanation (and designs) online beginning with the Wikipedia entry for “moiré effect”.

In the rest of this instructable, I will describe how to quickly design your own pattern to use (as I do) as an interesting looking decoration around your house.

Step 2: Choosing Your Animation

I will describe (in step 3) how to make the moiré figure and the moiré grid in Inkscape which is a free and open-source vector graphic editor, I will present every step of the process that should be clear enough for a inkscape beginner to follow (I am myself a relative beginner with inkscape).

First, decide what movement you want to make. You can find great design on line of multiple steps of the same animation (like the goose flying in the beginning) but to show you another way, I have here, started with a single image that we are going to try to “animate”.

The animation I want to create is fairly simple: the inkscape robot throwing its arms in the air. To add just a little bit a movement, I want to have the robot “dancing” in place by just changing the horizontal orientation of the robot.

Step 3: Creating Your Design

A. First import your image on the page (File>import>robot.png), duplicate your original image 2 times (a total of 3 picture of a complete robot).

B. Use the “DRAW FREEHAND LINES (P)” to circle the part of the robot we will move around ( for example the right arm) on one robot picture

C. Select both the image and the line you draw on top and click on Object>Clip>Set Clip (you should end up with one right arm of the robot and the remaining 2 duplicates of the original robot at this point)

D. Repeat step C on the left arm of the robot (you should have 1 right arm, 1 left arm and 1 complete robot)

E. Use the “DRAW FREEHAND LINES (P)” to circle the robot without its arms

F. Select both the image and the line you draw on top and click on Object>Clip>Set Clip (you should end up with one right arm, 1 left arm and 1 robot without its arms at this point)

G. Duplicate the armless robot and the pair of arms 3 times (you should end up with 4 right arms, 4 left arms and 4 armless robot at this point)

Note: We want to start with the robot with its arms along its sides and end up with the robot raising the roof, we have to rotate the arms from 0 to 180° within 4 pictures => 0°, 60°, 120°, 180°

H. select 1 right arm, go to Object>transform, a window opens up on the right side of the inkscape interface, on this new window, click on Rotate, in the dialog box “Angle”, right in “60” then at the bottom of the window, “Apply”

I. Repeat step H for 2 other right arms with “Angle” set to “120” and “180” respectively. Repeat the process for 3 of the 4 left arms with “Angle” set to “60”, “120” and “180” respectively.

J. Select all 8 arms and click on Object>Lower to bottom

K. Align each pair of corresponding arms (i.e. the 60° right arm with the -60° left arm) with one of the armless robot, to look slightly better, you can slide part of the arm under the robot

L. For each robot + corresponding arms, select them and click Object>group . This make each robot grouped with its arms

M. Stack the robots vertically with some space between each robot then select them all and click Object>Align and distribute, a window opens up on the right, click on “center on vertical axis”. You should place the robot in the “right” order, meaning in the right sequence of the animation top to bottom or bottom to top. For 2 non consecutive robot, select the robot in question and press Object>Flip Horizontally, This will make the robot look like its dancing from one feet to the other.

Note: We are now down with the robot, we are moving on to design an appropriate grid. For the reasons mentioned in step 1, “appropriate” leans that I am choosing a grid with a window size that looks ok with the picture I have used, you might have to adjust that. I am using a window of 1mm (leading to a blocker of 3mm) for a total pitch of 4mm

N. Draw a black rectangle of 3mm in length and the same height as your robot image (at the very least). Duplicate this rectangle enough times to cover the entire image, lets call the number of black rectangle “Nrectangle”. Place the “leftest” rectangle at x=0 (you can select your rectangle and enter x=0) and place your “rightest” rectangle at x= (Nrectangle-1)*Grid_pitch. Select all your rectangle and on the “Align” window on the right click on “Distribute horizontally with even spacing between centers” followed by “Center on horizontal axis”. With all the rectangle (and only the rectangles) selected, click on Path>combine. You should get your grid with the exact size window and blocker.

O. Duplicate this grid 4 times and place on top of every robot (you have one extra grid, do not put it on a robot, put it somewhere on the side). Center all the grids that are on a robot amongst themselves while making sure that every grid is completely on top of its robot. The grid should be oversize compared to the robot it is covering by at least one pitch.

P. Select the bottom robot and its superimposed grid, click on Object>Clip>Set Clip

Q. Move the second grid along the x axis by one window width (1mm for me) and repeat step P with this new robot and grid.

R. Repeat P and Q for the last 2 remaining robot+grid combos by moving the grid along the x axis by 2-window-width and 3-window-width respectively.

S. Select all 4 minced robot and click on Object>Align and distribute, a window opens up on the right, click on “center on horizontal axis”

T. This final step is making sure that the moiré effect that we design is working as we want. Make a negative of the previously made grid and drag is along your design and if everything works as you intended, you are good to go !

Step 4: Making the Physical Grid

The grid is made out of a black sheet of paper. The choice of the black color for the grid is simply because it is the color that makes the picture appear in the best way, especially since my design will be printed on a white background.

I have used a simple diode laser to cut out the windows on the sheet of paper, the grid that we used in the design stages is not perfect as I had to resize my picture (while of course keeping the proportion of the grid) for the company that printed my design onto the mug. This means that the ratio window to blocker is the same but the dimensions of the actual window will have to be measured on the actual physical object and the grid resized.

To measure the window, I have to identify in the mess that is the picture one window with and measure it with a caliper. I have redesigned my grid in inkscape using the dimension measured and the unchanged window/blocker ratio and cut it with the laser (process on how to convert a design in inkscape into a file for the laser cutter can be found here).

The obtained grid is quite flimsy, I reinforced mine with some clear packing tape.

Step 5: What Can You Do With That ?

So now the question is: good, what do I do with that then ?

I recently found out that there are plenty of object you can personalize a few dollars, from pen to hats and from lighters to mugs, I chose the latter and the resulting moiré animation works quite well (actually better than I anticipated) but not as well as on inkscape.

When you are choosing the substrate for your design, you have to keep in mind that you should have it printed on a surface as flat of as cylindrical as possible, you will not be able to make a grid to reveal a design printed on a surface with compound curves (geometrically you have to choose a surface that is parallel to an axis).