I and a cartographer friend have built a map of the Med starting with high resolution satellite image data for land areas (using color gradients for elevations, etc) and bathy depth data for seas to construct a 7200 x 4000 x 72ppi image. The file is huge and includes many, many layers (rivers, lakes, waves, dunes, "monsters", "routes", some raster & some vector), directly and via many linked smart objects.
My question to you experts is how to complete the workflow for printing, especially since this is NOT a photograph, if that latter point makes a difference.
1. The image will be upscaled/downscaled to 21,600 x 12000 x 360ppi. Right now, using Photoshop CC, but is, for example, Perfect resize better? How best to do this?
2. Should I use Topaz details and/or ACR's "clarity" for final contrast improvement? I realize this is a question of taste, but wonder if the upscaling/downscaling generally demand certain corrective actions?
3. I might print to metal (Bay) and might print to paper. Is NIC's output sharpener necessary/optional, at which settings, or should some other approach be used? The question again relates to the large upscalling/downscaling of other than photographic pixels, but also to metal vs paper?
I think this is not a mainstream Luminous Landscape question type but am hoping (and expecting) that the experts here can help me with this very-important-to-me project.
Thank you in advance.