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    PerceptualLift: Using hatches to infer a 3D organic shape from a sketch
    (The Eurographics Association, 2025) Butler, Tara; Guehl, Pascal; Parakkat, Amal Dev; Cani, Marie-Paule; Catalano, Chiara Eva; Parakkat, Amal Dev
    In this work, we investigate whether artistic hatching, popular in pen-and-ink sketches, can be consistently perceived as a depth cue. We illustrate our results by presenting PerceptualLift, a modeling system that exploits hatching to create curved 3D shapes from a single sketch. We first describe a perceptual user study conducted across a diverse group of participants, which confirms the relevance of hatches as consistent clues for inferring curvature in the depth direction from a sketch. It enables us to extract geometrical rules that link 2D hatch characteristics, such as their direction, frequency, and magnitude, to the changes of depth in the depicted 3D shape. Built on these rules, we introduce PerceptualLift, a flexible tool to model 3D organic shapes by simply hatching over 2D hand-drawn contour sketches.
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    View-Dependent Deformation Fields for 2D Editing of 3D Models
    (The Eurographics Association, 2025) Mqirmi, Martin El; Aigerman, Noam; Catalano, Chiara Eva; Parakkat, Amal Dev
    We propose a method for authoring non-realistic 3D objects (represented as either 3D Gaussian Splats or meshes), that comply with 2D edits from specific viewpoints. Namely, given a 3D object, a user chooses different viewpoints and interactively deforms the object in the 2D image plane of each view. The method then produces a ''deformation field'' - an interpolation between those 2D deformations in a smooth manner as the viewpoint changes. Our core observation is that the 2D deformations do not need to be tied to an underlying object, nor share the same deformation space. We use this observation to devise a method for authoring view-dependent deformations, holding several technical contributions: first, a novel way to compositionality-blend between the 2D deformations after lifting them to 3D - this enables the user to ''stack'' the deformations similarly to layers in an editing software, each deformation operating on the results of the previous; second, a novel method to apply the 3D deformation to 3D Gaussian Splats; third, an approach to author the 2D deformations, by deforming a 2D mesh encapsulating a rendered image of the object. We show the versatility and efficacy of our method by adding cartoonish effects to objects, providing means to modify human characters, fitting 3D models to given 2D sketches and caricatures, resolving occlusions, and recreating classic non-realistic paintings as 3D models.
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    A Blender Add-on for 3D Concept Sketching
    (The Eurographics Association, 2025) Wie, Jiayi; Bousseau, Adrien; Berio, Daniel; Bruckert, Alexandre
    We present a Blender add-on that bridges the Grease Pencil drawing interface with a symmetry-driven 3D reconstruction algorithm for concept sketches. On the one hand, Blender's Grease Pencil offers users a convenient interface to draw 2D concept sketches using vector strokes, drawn freehand or using vector primitives (straight lines, Bézier curves). On the other hand, the reconstruction algorithm of Hähnlein et al. [HGSB22] can lift such 2D sketches to 3D using symmetry correspondences. While this reconstruction algorithm was originally developed to be automatic, we show how it can be adapted to allow step-by-step reconstruction of a sketch as it is drawn, and to support user corrections. Finally, we compare the reconstructions obtained with this add-on to the ones produced by a recent generative model trained to produce a 3D shape from a single image.