Band Moire images

We propose a new powerful way of synthesizing moire images that enables the creation of dynamically moving messages incorporating text, symbols, and color elements. Moire images appear when superposing a base layer made of replicated base bands and a revealing layer made of a line grating comprising thin transparent lines. Each replicated base band contains the same image, e.g. text or color motifs. Since the base bands and the revealing line grating have similar periods, the revealed moire image is the image located within each base band, enlarged along one dimension. By considering the formation of the moire image as a line sampling process, we derive the linear transformation between the base layer and the moire image. We obtain the geometric layout of the resulting moire image, i.e. its orientation, size and displacement direction when moving the revealing layer on top of the base layer. Interesting moire images can be synthesized by applying geometric transformations to both the base and the revealing layers. We propose a mathematical model describing the geometric transformation that a moire image undergoes, when its base layer and its revealing layer are subject to different freely chosen non-linear geometric transformations. By knowing in advance the layout of a moire image as a function of the layouts of the base layer and of the revealing layer, we are able to create moire components running up and down at different speeds and orientations upon translation of the revealing layer. We also derive layer transformations which yield periodic moire images despite the fact that both the base and the revealing layers are curved. By offering a new means of artistic expression, band moire images can be used to create new designs and to synthesize visually appealing applications. © 2004 ACM

Moiré methods for the protection of documents and products: A short survey

Moiré effects have long been used for various applications in many different fields, including metrology, strain analysis, optical alignment, etc. In the present survey we describe some of the main applications of the moiré effect in the field of document and product security. We review the main families of moiré-based anticounterfeiting methods, compare them, and explain how they can be used for such security applications

Long range moiré patterns

Previous work has gone towards using moiré patterns formed with lenticular lenses to perform pose estimation for short ranges. This thesis investigates existing theory of moiré patterns, most notably the Fourier and first harmonic approximation models. This theory has been drawn upon to create a generalised model of planar moiré patterns in 3D. For example, those generated from two patterns with fine grids separated in space. This improves on previous research that does not investigate this specific kind of 3D pattern as closely. This thesis also developed a framework that simulates moiré patterns using this model. Along with this, the proposed framework can also solve pose information about a moiré pattern given an image. Experiments varying camera lateral translation were accurate for the close-range testing, with about 10 mm accuracy from a distance of 160 mm. Results from varying camera distance where 0–130 mm accuracy varied from ranges 100–2000 mm. A y-tilt estimation experiment was performed using the solver from this framework. At 3.116 m it was able to estimate an angle with an error of 5° for angles as wide as 30° and was able to estimate angles with an error of 0.25° for angles less than 5°. This is better than similar existing methods such as the Metria Moiré Phase Tracking marker’s maximum absolute errors of up to 2.8 mm and 2.1°

Modèles spectraux pour les surfaces imprimées : approches directes et problématiques inverses

Ce mémoire cherche à décrire et mettre en perspective une démarche scientifique construite durant une dizaine d’années de recherches dans le domaine de la reproduction des couleurs, un domaine associé aux disciplines de l’optique et des sciences de l’image. Les travaux présentés visent prédire le rendu visuel de surfaces traitées par divers procédés de coloration, et de créer des effets visuels nouveaux pour les arts graphiques à des fins esthétiques ou de sécurisation de documents. Les connaissances produites portent sur le développement de modèles optiques originaux décrivant la propagation de la lumière dans les couches colorantes et les supports, la métrologie optique nécessaire à la caractérisation de ces surfaces ou à la calibration des modèles, la conception d’effets visuels par impression grâce aux modèles inverses. Le travail de modélisation forme la partie amont de ces recherches. La caractérisation des surfaces et la conception d’effets visuels innovants font l’objet de collaborations industrielles avec des grandes ou petites. Les principaux résultats portent sur des configurations originales d’impression où plusieurs images en demi-tons sont vues l’une au travers de l’autre : impressions recto-verso, empilements d’imprimés… Des modèles propres à ces configurations ont été développés et des effets visuels, quasiment impossibles à obtenir sans modèle, ont été conçus. Une autre activité plus récente concerne de nouveaux procédés de marquage en couleur par laser sur des surfaces pré-fonctionnalisées. Par ailleurs, s’esquisse une démarche plus fondamentale sur l’interaction entre la lumière et les matériaux d’impression et sur la métrologie optique de surfaces à apparence variable

Bridging the Gap Between People, Mobile Devices, and the Physical World

Human-computer interaction (HCI) is being revolutionized by computational design and artificial intelligence. As the diversity of user interfaces shifts from personal desktops to mobile and wearable devices, yesterday’s tools and interfaces are insufficient to meet the demands of tomorrow’s devices. This dissertation describes my research on leveraging different physical channels (e.g., vibration, light, capacitance) to enable novel interaction opportunities. We first introduce FontCode, an information embedding technique for text documents. Given a text document with specific fonts, our method can embed user-specified information (e.g., URLs, meta data, etc) in the text by perturbing the glyphs of text characters while preserving the text content. The embedded information can later be retrieved using a smartphone in real time. Then, we present Vidgets, a family of mechanical widgets, specifically push buttons and rotary knobs that augment mobile devices with tangible user interfaces. When these widgets are attached to a mobile device and a user interacts with them, the nonlinear mechanical response of the widgets shifts the device slightly and quickly. Subsequently, this subtle motion can be detected by the Inertial Measurement Units (IMUs), which is commonly installed on mobile devices. Next, we propose BackTrack, a trackpad placed on the back of a smartphone to track finegrained finger motions. Our system has a small form factor, with all the circuits encapsulated in a thin layer attached to a phone case. It can be used with any off-the-shelf smartphone, requiring no power supply or modification of the operating systems. BackTrack simply extends the finger tracking area of the front screen, without interrupting the use of the front screen. Lastly, we demonstrate MoiréBoard, a new camera tracking method that leverages a seemingly irrelevant visual phenomenon, the moiré effect. Based on a systematic analysis of the moiré effect under camera projection, MoiréBoard requires no power nor camera calibration. It can easily be made at a low cost (e.g., through 3D printing) and ready to use with any stock mobile device with a camera. Its tracking algorithm is computationally efficient and can run at a high frame rate. It is not only simple to implement, but also tracks devices at a high accuracy, comparable to the state-of-the-art commercial VR tracking systems

Synthesis of superposition images for watches, valuable articles and publicity

The present invention aims at synthesizing superposition images formed either by band moire shapes or by shape level lines for making the information forwarded by valuable articles or by time pieces such as watches and clocks more dynamic, as well as for improving their attractiveness and aesthetics. A further application is publicity. For synthesizing band moiré images, the present invention relies on a band moiré image layout model allowing to obtain the layout of the base the band grating, given the layouts of the band moire image and of the revealing line grating. Base and revealing layer layouts may be conceived to create band moiré image shapes whose patterns move e.g. radially, circularly, or according to a spiral trajectory. Shape level lines occur in a superposition image when e.g. a base layer comprising modified sets of lines is superposed with a revealing layer comprising a line grating. Such a base layer embeds a shape elevation profile generated from an initial motif shape image (e.g. typographic characters, words of text, symbols, logo, ornament). By moving the revealing layer in superposition with the base layer, shape level lines move dynamically between the initial motif shape boundaries and shape foreground centers, respectively shape background centers, thereby growing and shrinking. The movement of the shape level lines creates visually attractive pulsing motif shapes, e.g. a pulsing heart or pulsing text. Categories of embodiments comprise (1) visually attractive articles having moving parts (watches, clocks, vehicles, publicity display devices, fashion clothes), (2) articles such as cosmetics, drugs, perfumes and wines, where one part is moved in respect to a second part, e.g. bottles having a lid or labels composed of two layers, (3) articles where the base layer and the revealing line grating are separated by a gap and form a fixed composed layer, and (4) articles where at least one of the layers is an electronic display