Watching Vin Diesel's Riddick (2013) was a jarring experience in many ways not least because of the quality of the CGI used. It could be best described as having a mid-2000s videogame-y feel to it. Reading up on the film's production issues suggests that this dearth in quality was due to budgetary constraints. Riddick was completed within a budget of 38M. Its prequel, Chronicles of Riddick on the other hand used up ~120M of 2004's dollars and certainly looked more polished.
What I'd like to know is, why the vast difference in quality? I can understand if the amount (as in length of time) of scenes with effects was limited. But Riddick does incorporate a lot of it. Did Riddick perhaps use a cheaper effects house due to its budget? Or do CGI firms bill based on the amount of rendering time? Also, shouldn't technology have advanced in the last 9 years to make it easier to realise 2004's quality in 2013 on a smaller budget?