Juan Pablo Roldán is a freelance concept artist and illustrator, based in Medellin, Columbia, who works in the gaming and film industries.
Roldán’s atmospheric environments and menacing characters are rendered digitally with an eye to theatrically dramatic value relationships and with a skilled suggestion of texture, whether organic or technological. Among his personal projects you can find some digital paintings of real locations in Columbia.
His blog seems to have been set aside in favor of his Tumblr site. In addition you can find his work on Art Station and CG Society.
He has a how-to on scale and perspective on Layer Paint.