Flora Ponjou Tasse

Partial 3D Shape Retrieval

In progress.

Shading Curves: Vector-Based Drawing With Explicit Gradient Control

Abstract

A challenge in vector graphics is to define primitives that offer flexible manipulation of colour gradients. We propose a new primitive, called a shading curve, that supports explicit and local gradient control. This is achieved by associating shading profiles to each side of the curve. These shading profiles, which can be manually manipulated, represent the colour gradient out from their associated curves. Such explicit and local gradient control is challenging to achieve via the diffusion curve process, introduced in 2008, because it offers only implicit control of the colour gradient. We resolve this problem by using subdivision surfaces that are constructed from shading curves and their shading profiles.

Shading Curves Teaser
Links
  • Lieng, H., Tasse, F. P., Kosinka, Jiří and Dodgson, N.A. (2015), Shading Curves: Vector-Based Drawing With Explicit Gradient Control. Computer Graphics Forum. [pdf]
Demo and Code

Feature-based terrain editing from complex sketches

Abstract

We present a new method for first person sketch-based editing of terrain models. As in usual artistic pictures, the input sketch depicts complex silhouettes with cusps and T-junctions, which typically correspond to non-planar curves in 3D. After analysing depth constraints in the sketch based on perceptual cues, our method best matches the sketched silhouettes with silhouettes or ridges of the input terrain. A deformation algorithm is then applied to the terrain, enabling it to exactly match the sketch from the given perspective view, while insuring that none of the user-defined silhouettes is hidden by another part of the terrain. We extend this sketch-based terrain editing framework to handle a collection of multi-view sketches. As our results show, this method enables users to easily personalize an existing terrain, while preserving its plausibility and style.

Shading Curves Teaser Shading Curves Teaser

Links
  • Tasse, F.P., Emilien, A., Cani, M.P., Hahmann, S. and Dodgson, N.A. (2014). Computers and Graphics, Elsevier, 2014, 45, pp.101-115 [url]
  • Tasse, F.P., Emilien, A., Cani, M.P., Hahmann, S. and Bernhardt, A. (2014). First person sketch-based terrain editing. In Proceedings of the 2014 Graphics Interface Conference (GI '14). pp.217-224. [url]
Demo and Code

Enhanced texture-based terrain synthesis on GPU

Abstract

We present a patch-based terrain synthesis framework constrained by user-specified curvilinear features such as ridges and valleys. A user specifies where terrain features appear in the generated terrain by providing a 2D sketch map or drawing 2.5D sketched curves in the sketching interface. A novel patch merging technique is proposed to remove boundary artifacts created by overlapping patches.

Links
  • Tasse, F. P., Gain, J. and Marais, P. (2012), Enhanced Texture-Based Terrain Synthesis on Graphics Hardware. Computer Graphics Forum, 31: 1959 - 1972. [url]
  • Flora Ponjou Tasse. Texture-based terrain synthesis on Graphics hardware (CUDA). M.Sc. Thesis. University Of Cape Town, 2011. [pdf]
Code
  • Terrain Navigator [github]
  • Terrain Generation (without sketching interface) [github]

Crowd simulation of pedestrians in a virtual city

Abstract

We present a crowd simulation behavioural model for simulating identified crowd phenomena in a virtual city such as street flows, crowd formation and road crossings. We propose a three-tier architecture model to produce intentions, perform path planning and control movement. We demonstrate that this model produces the desired behaviour associated with pedestrian navigation in a virtual city, which includes navigation, flow formation, circle creation and passageway crossing.


Links
  • Flora Ponjou Tasse, Kevin Glass, and Shaun Bangay, "Simulating crowd phenomena in african markets", In Afrigraph '09: Proceedings of the 6th international conference on Computer graphics, virtual Reality, visualisation and interaction in Africa, pages 47 - 52, Pretoria, South Africa. ACM Press, New York, NY, USA. 2009 [url]
  • Flora Ponjou Tasse, "Crowd simulation of pedestrians in a virtual city", Rhodes University. 2008 - [pdf]
Code