An update to the earlier series of videos on compositing. Not a real field of expertise for me, so some errors crept in - these are corrected here. I also look at how some of the workflow has changed in H12, and at how to render pixel samples as a larger image and use the result in compositing.
As always a project file is available at sites.google.com/site/pqhoudinitutorial/
Note: In H13 the property 'Ignore geometry attribute shaders' is by default on each object node. Adding to the mantra node as I do here will not work, because the value on the mantra node will be overridden by the values on the object node. Instead create a take, select all the object nodes for objects where you have geometry level shading and add the 'Ignore geometry attribute shaders' to the take, and ensure the box is ticked. Then use this take for the ambient occlusion, shadow render or whatever.