Continuity mapping for multi-chart textures

Abstract

Figure 1: Filtering with Continuity Mapping (Snake from www.daz3d.com, 25448 triangles, atlas 700 × 3200). In spite of the artist's fine-tuning, seams are visible with padding alone (top). Continuity Mapping makes any multi-chart parameterization seamless (bottom). AbstractIt is well known that multi-chart parameterizations introduce seams over meshes, causing serious problems for applications like texture filtering, relief mapping and simulations in the texture domain.Here we present two techniques, collectively known as Continuity Mapping, that together make any multi-chart parameterization seamless: Traveler's Map is used for solving the spatial discontinuities of multi-chart parameterizations in texture space thanks to a bidirectional mapping between areas outside the charts and the corresponding areas inside; and Sewing the Seams addresses the sampling mismatch at chart boundaries using a set of stitching triangles that are not true geometry, but merely evaluated on a perfragment basis to perform consistent linear interpolation between non-adjacent texel values. Continuity Mapping does not require any modification of the artist-provided textures or models, it is fully automatic, and achieves continuity with small memory and computational costs.

Invisible Seams

“…Discussion Our approach provides a continuous result through a single standard texture lookup (contrary to [BD02, PCK04, CHCH06, LD07, YKH10, GP09]), it does not constrain charts to be axis aligned in uv space (contrary to [PCK04, CHCH06]), which can lead to excessive distortion requiring to modify the input mesh [CHCH06]. In addition we support adaptive resolution and several magnification modes.…”

“…In addition we support adaptive resolution and several magnification modes. The drawbacks of our approach are that it computes a new set of uv coordinates rather than fixing existing ones (contrary to [GP09]), that it inputs a GPP which computation is still an active area of research, and that MIP‐mapping support is limited. On this last point, please note that at worst MIP‐mapping gives results equivalent to standard MIP‐mapping of texture atlases.…”

“…Gonzalez et al . [GP09] use a dedicated fragment shader to match colors by triangulating the seams. Other schemes rely on non‐planar domains [THCM04, YKH10] or store colors in a volume hierarchy surrounding the object [BD02, LD07].…”

Rethinking Texture Mapping

“…Though not directly useful for texture mapping purposes, the concept of seamless These prior schemes attempt to remove the seams as seen through a standard texture lookup. Other approaches modify the interpolation to hide seams during rendering [GP09]. Here, the local geometry across chart boundaries is stored into the texels as small triangle lists.…”

The ViRVIG Institute

“…3) Continuity Mapping of Multi-chart Textures: Continuity mapping can make any multi-chart parameterization to Figure 6), with small memory and computing costs [11]. commercial modeling systems, as well as some novel features that make it a unique system, like a graph-based paradigm that allows the user to create content rich cities with distinct districts, major and minor roads, blocks, lots and buildings, and also other urban elements like streets, sidewalks, parks, bridges and landmarks [12].…”