Magic on a Plane: Lenticulars

Not Just for Crackerjacks Anymore

Those little stamp-sized cards in a box of Crackerjacks introduced this technology to many of us. The card bore a surface of fine parallel plastic ridges on the front; a cartoon would move when the card was tilted at varying angles.

The technology of lenticular printing like this has become more sophisticated over the years. There are a variety of visual effects that one can achieve, from 3D to morphing to animation. These effects are set up using image-editing software, such as Adobe Photoshop, that allows for layered files. The resulting product can be a great attention-grabbing device for delivering a science message or for inspiring the imagination of a young scientist.

Our office at NASA Goddard Space Flight Center in Greenbelt, Maryland, produces and distributes science outreach materials aimed at informing the public about Earth and the space sciences. Along with our normally printed items, those on paper, we also appeal to the public through the use of lenticular products—postcards, rulers, bookmarks—which we hand out at public events and conferences. Lenticulars have been very successful in bringing science to the general public. They attract attention and can inspire further study. The back of the card provides an added opportunity for printed information.

So, What Are They?

The simplest definition of lenticular printing refers to a manipulated printed image covered by a thin sheet of fine, parallel, plastic ridges, a lenticular lens. Together, they work to create one or more illusions when tilted: alternating flip images, morphing, zoom effects, video-like animation, and 3D; that is, illusions of motion and depth, or a combination.

  • Flip: This effect is comprised of two or three distinct images that can show change, motion, or a comparison.
  • Morph: One object changes into another. These objects, taken by themselves, can be completely unrelated.
  • Zoom: A type of motion that simulates the enlargement (zooming in) and reduction in size (zooming out) of an object or type.
  • Animation: This effect can use multiple frames from a video clip or frames created another way to simulate action.
  • 3D: a hologram-like like effect simulating depth. These effects are achieved through the use of layered image files, such as those created with Adobe Photoshop. Setting Up a File

All visual effects for lenticulars are based on the ordering of layers in a digital image file. For motion effects—flip images, morphing, zoom, animation—the file’s layers correspond to frames in a sequence, whether it’s the changing stages in the development of a beetle or the progression of a solar flare. The layer order will determine the order of the action.

Depending on the fabricator you use, the number of layers available in the making of a lenticular can be 12-16. However, not all layers are available for the designer’s use. For motion effects, about six layers may be used to ensure a crisp start and finish to the sequence, three at the start of the sequence, three at the end. For products at our office, we usually have between four and six layers with which to actually design.

For a 3D effect, the layers in your file correspond to depth. The bottommost layer will be treated as the background, the layer above that will overlay it, and so on. The effect achieved for 3D, then, appears to contain several layers floating one above the other, a hologramlike quality.

For Example…

1. Day-Night Earth:

Figure 1 is a postcard-size example (4 inches x 6 inches) of a simple flip effect, showing comparison. In this case, we wanted to show Earth by day and Earth at night, highlighting the city lights of the developed world. So, on this card, there are two images cycling back and forth.

This is a simple file, just three layers (Figure 2). The black background layer is at the bottom. It contains small stars, the NASA logo, and one line of type across the top-left. This layer is stable and none of these elements change.

Above that layer is the nighttime Earth, just an Earth image without background, showing the continents and city lights. In the layer above that, third from the bottom, is the daytime Earth, also without background, showing the continents and ocean. This layer lines up precisely with the nighttime Earth beneath.

By tilting the card, the image changes from daytime Earth to nighttime Earth showing the continents and then the nightlights. The card shows the location of those countries technologically developed enough to have electricity.

2. 3D Solar System:

The next example (Figure 3) is a 3D lenticular card (4 x 6) showing the solar system with some additional elements. You can see there are many more layers here (Figure 4) than in the flip example, about 16. As there is no motion or otherwise changing imagery on this card, just straight 3D, I have more layers available to design with. The background image is a nebula with some added stars. Titan’s layer is above that (upper right corner on the card), then, the layer with the furthermost orbits, then Neptune, and so on. The topmost layer here is an Earth inset. They are ordered in the Layer Palette bottom to top as on the card itself, background to foreground.

As an added bonus, the vendor was also able to create a spherical effect for Earth. This is an effect supplied by the vendor, and is not something I needed to add, myself. However, adding a spherical effect also takes up layers. So, some of my Photoshop layers were merged by the vendor in production. Those objects now share depth levels on the card with other objects not originally intended, but it’s a subtle difference. Still, I used so many layers already that Earth ended up being only modestly spherical. But it is still noticeable. Earth appears to bulge slightly.

On the reverse side of the card, we added information about how the Earth image (with the nighttime lights) was created, in addition to the general topic of our place in the solar system (Figure 5).

3. Lenticular Ruler:

This last example (Figure 6) pulls out all the stops. It is a 12-inch ruler using a combination of motion and 3D: a flip effect (Earth at the top), 3D (the background nebula/ stars), a flip-3D combo (Saturn’s rings), and an animation (a solar flare in four stages). You can see that the layer count is much higher (Figure 7). Hidden in these palette layers are 2 Earths showing melting sea ice, 2 views of Saturn’s rings, 4 labels for the sciences named (these turn off and on), and 4 solar flare frames. This is a more complicated piece by far.

Additionally, this vendor was also able to spherize the sun and planets. Again, the trade-off is as described in the previous example: the spherizing is indirectly proportional to the number of layers; several layers had to be merged in production to allow for a modest spherizing effect for the planets and the sun.

We have used this technology over a number of years to produce a wide variety of lenticulars for the public and have had overall great success in attracting the public and science community. In addition to the numerous adults that have come to visit the NASA exhibit booth at public events we attend, a number of teachers and parents gather up materials for children and are attracted especially to our lenticular handouts.

Resources

More on lenticular printing:
http://lenstar.org
http://www.lenticularprinting.org

Some simulations from various vendors:
http://www.world3d.com/gallery.html
http://www.extremevision.com/
http://www.tracer1.com/what/lenticular_effects

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