Membrane protrusions that occur on the dorsal surface of a cell are an excellent experimental system to study actin machineries at work in a living cell. Membrane protrusions that rise and completely encapsulate extracellular volumes to perform pinocytic or phagocytic functions are controlled by small GTPase Rac1. Here, capitalizing on a combination of optogenetic approaches with lattice light-sheet microscopy, we demonstrate that Rac1 activation leads to a regime in membrane ruffling dominated by polymerization, and deactivating Rac1 leads to complex contractile processes leading to formation of macropinosomes. Further, we explore if actin polymerization alone is able to form linear membrane protrusions or a more sophisticated feedback between curvature sensing IRSp53 (an I-Bar protein) and actin nucleators are involved. We also discuss the use of virtual reality (VR) based image analysis for such complex membrane protrusions.