This is the author accepted manuscript. The final version is available from SPIE via the DOI in this record.The Planet Formation Imager (PFI) project aims to image the period of planet assembly directly, resolving
structures as small as a giant planet’s Hill sphere. These images will be required in order to determine the key
mechanisms for planet formation at the time when processes of grain growth, protoplanet assembly, magnetic
fields, disk/planet dynamical interactions and complex radiative transfer all interact – making some planetary
systems habitable and others inhospitable. We will present the overall vision for the PFI concept, focusing
on the key technologies and requirements that are needed to achieve the science goals. Based on these key
requirements, we will define a cost envelope range for the design and highlight where the largest uncertainties
lie at this conceptual stage
