Sidonie Christophe

Creative Colours Specification Based on Knowledge (COLorLEGend system)

Abstract In map design, user’s choices of graphical signs may be unsuitable to their needs. In particular, colours choices may disturb the reading and understanding of maps. We propose a methodology to help users to make personalized and original colours specifications. It implies offering cartographic expertise and favouring creativity. The paper handles with knowledge for colours specification coming from visual perception, cognitive sciences, graphic semiotics, cartography and art. We specify a knowledge base made-up of cartographic rules (semantic, contrasts and conventional), artistic rules and inspiration sources (map samples and famous paintings). The COLorLEGend system based on this knowledge allows users to make various colours specifications and maps, depending on cartographic and artistic colours uses. Lors de la conception cartographique, les choix des éléments graphiques faits par un utilisateur peuvent ne pas répondre à son besoin. En particulier le choix des couleurs peut perturber la lecture et la compréhension de la carte. Nous proposons une méthode pour aider un utilisateur à définir des couleurs personnalisées et originales. Cela nécessite de mettre à disposition une expertise cartographique et de favoriser la créativité. Ce papier décrit des connaissances nécessaires à la spécification de couleurs, connaissances empruntées aux domaines de la perception visuelle, des sciences cognitives, de la sémiologie graphique, de la cartographie en général et de l’art graphique. Nous avons défini une base de règles composée de règles cartographiques (sémantiques, contrastes colorés et règles conventionnelles), de règles artistiques et de sources d’inspiration (des exemples de cartes et des peintures célèbres). Le système COLorLEGend basé donc sur ces connaissances permet à un utilisateur de choisir différentes spécifications de couleurs pour ses cartes selon des usages de couleurs artistiques ou cartographiques.

Constrained palette-space exploration

Color palettes are widely used by artists to define colors of artworks and explore color designs. In general, artists select the colors of a palette by following a set of rules, e.g. contrast or relative luminance. Existing interactive palette exploration tools explore palette spaces following limited constraints defined as geometric configurations in color space e.g. harmony rules on the color wheel. Palette search algorithms sample palettes from color relations learned from an input dataset, however they cannot provide interactive user edits and palette refinement. We introduce in this work a new versatile formulation enabling the creation of constraint-based interactive palette exploration systems. Our technical contribution is a graph-based palette representation, from which we define palette exploration as a minimization problem that can be solved efficiently and provide real-time feedback. Based on our formulation, we introduce two interactive palette exploration strategies: constrained palette exploration, and for the first time, constrained palette interpolation. We demonstrate the performances of our approach on various application cases and evaluate how it helps users finding trade-offs between concurrent constraints.

Expressive Map Design Based on Pop Art: Revisit of Semiology of Graphics?

Is aesthetics an objective in the map design process? This question echoes our long-term research: does aesthetic quality improve map efficiency? In this paper, we discuss the notions of aesthetic response, objective and experience proposed by Kent (2005), and their relevance for making more expressive personalized maps. We first present the state of present research related to these notions and our interpretations. Then we present asystematic approach for rendering geographic data in a cartographic style based on the visual properties of Pop Art; the resulting maps are more vibrant and expressive. We consider this result a first step towards enhancing map quality. The proposition of a Pop Art cartographic style leads us to revisit some theoretical and practical principles of Semiology of Graphics (Bertin 1967), considering our experience with color contrasts and new approach for using texture. We conclude that expressive cartographic renderings would be useful for every mapmaker, and in the context of personalized map design, providing more elaborate tools could improve the design process and the resultant maps. Improving map quality is a question of managing visual variables in a traditional way—according to Bertin’s Semiology of Graphics —but also in a more artistic way, in order to find better cartographic representation according to the preferences, needs, and purposes of the mapmaker.