Space-time plots showing the evolution of dust radiation intensity (top row), optical depth (middle row), and cumulative flux (bottom panel) at 3 mm. Columns from left to right correspond to the fiducial model, model with a lower M_core, and model with higher α_visc. The white contours in the top and bottom rows delineate the radial locations, within which 95% of the total flux is contained. The white curves in the middple row highlight the regions with the optical depth >1.0. The units for radiation intensity and flux are erg cm⁻² s⁻¹ Hz⁻¹ sr⁻¹ and erg cm⁻² s⁻¹ Hz⁻¹, respectively.