What are the current open problems in Computer Graphics? I did a quick investigation about the topic but there doesn't seem a decent resource to find related problems without digging into latest CG papers (unlike CS problems you can easily find a Wikipedia list)

With open problems I mean phenomenas that still do not have a tractable solution/approximation to find its way into CG and better yet real time CG.
There is a vast amount of open problems in real-time graphics: shadows, aliasing, reflections, global illumination, transparencies (blending order and lighting) etc.

SIGGRAPH annually hosts a course called "Open Problems in Real-Time Rendering", which describes current issues in real-time graphics (mostly game dev industry standpoint). You can find last year's materials here: http://openproblems.realtimerendering.com