  Joint survey processing (JSP) is the pixel level combination of LSST, Euclid,
and WFIRST datasets. By combining the high spatial resolution of the
space-based datasets with deep, seeing-limited, ground-based images in the
optical bands, systematics like source confusion and astrometric mismatch can
be addressed to derive the highest precision optical/infrared photometric
catalogs. This white paper highlights the scientific motivation, computational
and algorithmic needs to build joint pixel level processing capabilities, which
the individual projects by themselves will not be able to support. Through this
white paper, we request that the Astro2020 decadal committee recognize the JSP
effort as a multi-agency project with the natural outcome being a collaborative
effort among groups which are normally supported by a single agency. JSP will
allow the U.S. (and international) astronomical community to manipulate the
flagship data sets and undertake innovative science investigations ranging from
solar system object characterization, exoplanet detections, nearby galaxy
rotation rates and dark matter properties, to epoch of reionization studies. It
will also result in the ultimate constraints on cosmological parameters and the
nature of dark energy, with far smaller uncertainties and a better handle on
systematics than by any one survey alone.
