While googling the net, I found this remark­able piece. This is a patent appli­ca­tion from 2010, and from the draw­ings, it seems that the inven­tor had the ‘rev­o­lu­tion­ary’ idea of cal­cu­lat­ing some adap­tive depth bias based on the depth map to improve shad­ow mapping.

The note­wor­thy part of the sto­ry is, that the offi­cial research, the patent clerk appar­ent­ly turned up my ShaderX⁴ arti­cle from 2006, as can be seen here fur­ther down on the page. The page also states that the appli­ca­tion has been aban­doned. So, maybe the exis­tence of this arti­cle has pre­vent­ed a patent on shad­ow maps, or at least dis­cour­aged the issuer to pur­sue the appli­ca­tion. In either case, let’s hope it stays that way!

We can draw two con­clu­sions from this.

• Con­clu­sion 1: ShaderX seems to be rec­og­nized by the EPO as a source of state of the art.
• Con­clu­sion 2: If you have an idea, write about and pub­lish it! It does­n’t mat­ter if it is just a blog post. If it can be tracked down, this can pre­vent a patent on the same idea in the future!