A recent posting on the gislist about watermarking vector GIS data led to the link for this interseting article on the topic:
I just skimmed the article, but I plan on reading it in more detail. This is an interesting topic. A common method of watermarking vector GIS data is adding "fake" features, like road segments that don't really exist. But I have often thought that there has got to be better ways of placing a watermark. The tricky part is embedding a watermark that can resist translation, rotation, and scaling. (Or even reprojection to a new coordinate system.) This rules out using any coordinate geometry to record the watermark.
Perhaps using the topology of features that remain intact despite translation, rotation, and scaling would be a valid way to watermark vector GIS data without "polluting" the dataset with fake features.
I'll have to chew on this some more. Might be cool to add a vector GIS data watermarking plug-in to OpenJUMP.
The Sunburned Surveyor