Table of Contents
The 3D watermarking techniques are still evolving and researchers are coming up with new novelty ways of ensuring robust and high capacity watermarks in the industry. The concern is more specifically driven by the increased application of 3D images in contemporary applications, including computer games and video. This paper is a summary of four innovative techniques for application of 3D watermarking techniques and how different researchers propose the application of each technique in watermarks.
Progressive Watermarking on 3D Meshes
The recent years have witnessed an increase in the number of researches based on reversible data because of its wide applications. Watermarks provide a number of algorithms used in 3D models. Most researches done in this field introduce new methods like the use of histograms in modeling 3D images. Most of the new models developed through research enhance the removal of payload information to achieve higher calculations of image pixels. Nevertheless, the methods introduced come with several disadvantages such as the requirement of that minimum and positioning of relevant. Most of the introduced methods in watermarking the 3D are still complex in their usage because of the limited capacity owing the peak-valley pairs required in the implementation of histogram to depict natural images. The technique of calculating integer parts in the coordinates for the foundation of 3D models in order to form histograms that allow minimum and maximum shifting of data between them to allow space for watermarking is widely used in modern 3D watermarking.
One way of expressing 3D models is the use of triangle mesh. In this technique, embedding process is achieved through the length of watermark which is embedded as a way of extracting precise watermarks. The main concern in this model is achieving of high capacity and bigger signal-to-noise ratios, satisfaction for the demand of invisibility, and, finally, robustness to attacks during the process of watermarking. In triangle mesh technique, the algorithm introduces distance ratios between the vertices of the image and thus allows for translation, rotation, and uniform scaling of watermarks while leaving the original model in a state that promotes exact and complete extraction. The technique also provides a strong capacity to resist any form of noise that may be introduced during the inverse proportion process while also promoting the invisibility of the original image. The applicability of an efficient watermarking technique lies in the kind of capacity, level of distortion and the robustness that the technique used provides to the user. A number of factors including translation, uniform scaling of images, as well as the rotation that can be achieved also play an important role in enhancing the usability of the technique. Moreover, different techniques such as varying the distances between the vertices can be applied in embedding 3D watermarks in an image. Removal of the need to have payload information is also another step that contributes to the achievement of high capacity in 3D watermarking. Varying the distance thus must not cause great changes in the coordinates of an image which can translate to distortion of images (Ji, Yang, Zhang & Gao, 12).
A Visually-Enhanced Approach to Watermarking 3D Models
The technique used in visually-enhanced approach to watermarking 3D models involves two major phases. These include that of identifying the salient regions using the saliency measure on 3D mesh surfaces and also performing a selective embedding of watermarks through statistical analysis which allows for modulating of mesh geometry in the regions where extraction is to be done. The whole process is guided by the focus on the salient shape in the 3D mesh to identify areas of differences with the surrounding objects. The technique utilizes heavily the saliency measure that allows for evaluation of saliency at every vertex through analysis of difference in the mean curvature of the surface. This is done in relation with other vertices in the surrounding area. Basically, it utilizes the distance ration between vertices by employing mathematical applications as regards to finding actual differences. The technique also utilizes the use of mathematical calculations to avoid disturbing the established repetitive patterns which exist in the surface shapes during the time of modulating the geometry with the watermarks. The main concern is to provide a blind watermarking scheme which can sustain the watermark throughout the whole transformation process and the changing of local geometry as well as the topology of 3d mesh. This process ensures a smooth triangulation and a distortion free procedure that allows similarity of images produced thereafter (Nakazawa, Kasahara & Takahashi, 25)
The model allows for watermarks to be created using 3D meshes with capacity to account for the visual saliency witnessed in the shapes of the meshes. It also allows for the embedment of copyright information in the 3D mesh without causing disturbance normally associated with the visual appearance of 3d shapes. The disadvantage of this model is that it does not keep the commendable success rates in extracting watermarks especially during the distribution of vertex norms because of the high unbalance nature of the images. This is mainly caused as a result of using watermarks in computer aided designs and models which have larger flat regions leading to limited salient regions. It also contributes to a uniform distribution of salient vertices that are evident in the histogram. This area requires future research using the adjustment segmentation technique in terms of the available salient regions, the size of the histogram bins as well as the tolerance capacity value of the inconsistency of each bin.
Optimized 3D Watermarking for Minimal Surface Distortion
Digital watermarking in 3D models is mainly aimed at filling the existing gaps in the area ofnon-visibility, robustness, high bit capacity and crypto-security. Anew methodology of performing 3D models watermarks with minimal surface distortion using the Levenberg–Marquardt optimization is proposed by the researchers. The aim is to minimize the sum of the distances between vertices as displaced by watermarks in relation to the original surface. Mainly, the procedure has been used in the fitting of graphical objects, processing of shapes, and producing watermarked images and thus provides a starting point for the application of the process using a new approach. The method provides a number of features such as watermarking security which are not clearly defined in the other methods already discussed. The method also analyses the data using complex but proven data analysis methodologies that ensures that the verification of measurements in the 3D watermarking process does not allow for variations in the distances between the watermarked image and the original image. The evaluation of results from experiments and the robustness of watermark assessment is an indication that the method provides well enhanced and proven procedures in providing a tight and robust watermarked image. It also relies on the Evaluation of the Bit-Capacity and of the Embedding Strength Factor as elements which are equally important in providing a sustainable watermarking process during the process of producing multiple and similar images. The important element in this method is the minimization of the object distortion using embedded histograms through displacement of locations of the vertices. It also utilizes the surface area function error which is important in the minimization of distortion as well as enforcement of smoothness (Bors & Luo, 188).
A New Reversible Watermarking of 3D Models Based on Ratio Expansion
The new reversible watermarking depends on proper data selection, ratio expansion which allows for a series of watermarks to embed on the image using data which is represented by floating point numbers. This model allows for transformation of the watermark in whichever form whether its 3D model, image, or even text. The other important step is the processing of the embedded data which makes it possible for the embedding process to allow for lengthy images, to be embedded as a way of extracting precise watermarks. Because the ratios are expandable, there is no need to save information while embedding. The last procedure is the extraction process which is basically the reverse of data embedding process and allows for the restoration of the original model and extraction watermarks in the image, text, 3D model which has been watermarked (Ji, Yang, Zhang & Gao, 3899)
The methods presented by researchers provide unique and innovative ways of approaching watermarking in 3D models. Each approach has its advantages and disadvantages. However, their presence and application in the modern watermarking will contribute to the growing area of watermarking, especially with its increase in video and computer games application. The processes summarized in this paper are coming from novice researchers who use studies of other researchers and new mathematical and statistical analysis of original images to come up with 3D meshes. Some of the developed techniques permit the hiding of the watermarks in 3D mesh while preserving their visual appearance without referring to the original images and thus helping to address the issue of copyright. Existing watermarking techniques focus on the robustness and shielding of any attacks to the image as a way of changing the copyright information implying that they do not fully protect against influences on the visual quality of the 3D model watermarks. They also cannot protect against disturbance of the original appearance of the 3D models thus undermining the visual quality in digital contents.