Yu-Ming Cheng

An Efficient Information Hiding Algorithm for Polygon Models

We present an efficient digital steganographic technique for three-dimensional (3D) triangle meshes. It is based on a substitutive blind procedure in the spatial domain. The basic idea is to consider every vertex of a triangle as a message vertex. We propose an efficient data structure and advanced jump strategy to fast assign order to the message vertex. We also provide a Multi-Level Embed Procedure (MLEP), including sliding, extending, and rotating levels, to embed information based on shifting the message vertex by its geometrical property. Experimental results show that the proposed technique is efficient and secure, has high capacity and low distortion, and is robust against affine transformations (which include translation, rotation, scaling, or their combined operations). The technique provides an automatic, reversible method and has proven to be feasible in steganography.

A high-capacity steganographic approach for 3D polygonal meshes

We present a high-capacity steganographic approach for three-dimensional (3D) polygonal meshes. We first use the representation information of a 3D model to embed messages. Our approach successfully combines both the spatial domain and the representation domain for steganography. In the spatial domain, every vertex of a 3D polygonal mesh can be represented by at least three bits using a modified multi-level embed procedure (MMLEP). In the representation domain, the representation order of vertices and polygons and even the topology information of polygons can be represented with an average of six bits per vertex using the proposed representation rearrangement procedure (RRP). Experimental results show that the proposed technique is efficient and secure, has high capacity and low distortion, and is robust against affine transformations. Our technique is a feasible alternative to other steganographic approaches.

An adaptive steganographic algorithm for 3D polygonal meshes

This paper presents a new adaptive digital steganographic technique for three-dimensional (3D) polygonal meshes. It is based on an adaptive substitutive blind procedure in the spatial domain. We use angle features to remove all restrictions of fixed embedding size in each vertex to provide larger embedding capacity and to minimize the distortion by minimum distortion distance estimation. This method exploits the correlation between neighboring polygons with respect to the human visual system to estimate the degree of smoothness or roughness properties. If the vertex is located on a rough surface, then it may tolerate larger position changes by embedding more messages than those on smooth surfaces. Our method provides an easy way to produce a more imperceptible result. In addition, a simple contagious diffusion technique is devoted to improving performance for polygonal meshes traversal. Experimental results show that the proposed technique is adaptive, simple, efficient, general, and secure. This technique has high capacity and low distortion, and it is robust against affine transformations. Our technique provides an adaptive method and has proven feasible in steganography.

A Novel Approach to Steganography in High- Dynamic-Range Images

A steganographic method for hiding messages uses high-dynamic-range images. The technique provides for authentication, a large embedding capacity, and limited distortion.

Steganography for three-dimensional models

We present a data hiding algorithm for 3D models. It is based on a substitutive procedure in the spatial domain. We propose a Virtual Multi-Level Embed Procedure to embed information based on shifting the message point by its virtual geometrical property, the order of which is assigned by principal component analysis. We have defined and validated an effective metric of distortion anticipation, which can help us easily anticipate and control the distortion rate. Experimental results show that the proposed technique is efficient and secure, has high capacity and low distortion, and is robust against affine transformations. It provides a reversible method and has proven to be feasible in data hiding.

Tunable bounding volumes for monte carlo applications

Luminaire sampling plays an important role in global illumination calculation using Monte Carlo integration. A conventional approach generates samples on the surface of the luminaire, resulting in rendered images with high variance of noise. In this paper, we present an efficient solid angle sampling technique using tunable bounding volumes for global illumination calculation. In contrast to the conventional approach, our technique derives samples from the solid angle subtended by the luminaire. In the construction process, we build a convex, frustum-like polyhedron as a bounding volume for a light source. Front-facing polygons of the bounding volume are then projected onto the unit hemisphere around the shaded point. These projected polygons represent the approximated solid angle subtended by the luminaire. The third step samples the projected spherical polygons on which a number of stratified samples are generated. We employ various types of light sources including ellipse, elliptic cylinder, elliptic cone and elliptic paraboloid. We perform our technique for Monte Carlo Direct Lighting and Monte Carlo Path Tracing applications. Under similar sample numbers, our technique produces images with less variance of noise compared to the conventional method. In addition, our technique provides roughly equal image quality in less execution time. Our approach is simple, efficient, and applicable to many types of luminaries for global illumination calculation.

Steganography on 3d models using a spatial subdivision technique

This paper proposes a new steganography algorithm for 3D models using a spatial subdivision technique. Our algorithm first decomposes the bounding volume of the cover model into voxels based on a Binary Space Partitioning (BSP) tree. The voxels are then further categorized into eight subspaces, each of which is numbered and represented as three-digit binary characters. In the embedding process, we first traverse the BSP tree, locating a leaf voxel; then we embed every three bits of the payload message into the vertex inside the leaf voxel. This is realized by translating a vertexs current position to the corresponding numbered subspace. This technique is a substitutive blind extraction scheme, where messages embedded can be extracted without the aid of the original cover model. This technique achieves high data capacity, equivalent to at least three times the number of the embedded vertices in the cover model. In addition, the stego model has insignificant visual distortion. Finally, this scheme is robust against similarity transformation attacks.

A novel data hiding algorithm using normal vectors of 3d model

This paper presents a novel data hiding algorithm for 3D polygonal models whose vertices have given normal vectors. The key idea of our algorithm is to embed messages by adjusting the normal vector of a vertex according to the pivot vector. All vertices in a 3D model can be embedded with multiple-bit payloads by using multiple pivot vectors. The distortion is measured by the angle between the adjusted normal vector and the original normal vector to distortion. A distortion coefficient is also introduced to control the distortion rate during the embedding process. Experimental results demonstrate that our algorithm can achieve high data capacity (up to 12 bits per normal vector), and is robust against rotation, translation, and uniform scaling attacks.