我們的研究主要是在無遠弗屆的網路上利用semi-fragile watermarking來確保3D models的完整性。浮水印是以3D model本身的資訊及種子數（如使用者的合法註冊號碼）產生的亂數所組成，不需使用額外的資訊。驗證浮水印時只要以原種子數利用簡單的數學運算便可以評斷models的完整性。我們所提的方法可以抵擋放大、縮小、平移等常見的3D models處理，也可以抵擋點順序重新排序等攻擊。嵌入方法對3D models外型的影響非常小，因此本方法適用於精密機具或醫學的3D models。我們的方法經過實驗證明其時間及效能都令人滿意。 In this study, a semi-fragile watermarking scheme based on vertex geometry is proposed for 3D model authentication. Watermark is generated from 3D model and random number generator by a seed number. To embed and extract watermark only needs the seed number and some simple arithmetic operations. Our method is robust to general 3-D model processes, such as uniform scaling, translation, and vertex reordering. The embedding process has little impact to the original 3D models that PSNR values can be up to eighties or nineties. Thus the proposed method is very suitable for precision instruments or medical science models. Experiments demonstrate that our method is time and performance satisfactory.
