Forum: Poser - OFFICIAL


Subject: Mesh watermarking

kawecki opened this issue on Sep 14, 2004 ยท 23 posts


kawecki posted Tue, 14 September 2004 at 4:28 AM

It was mentioned at another forum the possible use of watermarks for protecting meshes. This is a copy of my analysis about this subject: There is a big problem to where put the fingerprints, let us analyze the case of an *.obj file. You can divide the obj file in - The text - Vertices information - Texture vertices information - Normals information - Faces information The text (any extra thing and comments) and the normals information is not used by Poser and importing/exporting destroys all this information, so you can't put the fingerprint there. Remains - Vertices information - Texture vertices information - Faces information You can't put the fingerprints in the face information because it will create extra or wrong faces destroying your model. Remains - Vertices information - Texture vertices information If your remap the model all original texture information is lost, so you can't put the fingerprints there. So, only remains the vertex information for the watermark. If you put the watermark as extra vertices don't used by the model the watermark will be destroyed by any mesh cleaner software, so only you can put the fingerprint in the used vertices information. The watermark has to be able to survive to any order change of the vertex list. So the only way is to put the fingerprint is as a slight deformation of the vertex coordinates in a 3d space. But any morph can destroy completely this watermark because it cause severve deformation to the spatial information. You can't put the watermark in a specific location because if you cut those part of the mesh the watermark is destroyed. The only way is to put the watermark is in all the mesh, so if the you take a part of the mesh, unless is too small, the watermark is still present in that part, the same way as is done with pictures, but as in case of images watermark are easely destroyed and the mesh is subject to more severe manipulations than the image. Another big problem is than an image for example of 800x600 has 480000 points and a typical mesh can have less of 50000 vertices or even 3000 vertices, this number is very small for watermarks! An image of 200x200 has 40000 points and you can't put watermarks in small pictures, the normal jpeg compression process destroys the watermark! So, for small images with watermark you have to use bmp of tiff and never jpeg. Conclusion: The mesh watermark can be only be usefull for identifying models that have not been manipulated, watermarks have very limited application, the rest is illusion or propaganda of vendors. Remember that I kave not mentioned the use of softwares designed for removing watermarks, so if with normal manipulation the result is bad for fingerprints, using these softwares the result is tragic.

Stupidity also evolves!