You will lose quality as you enlarge ​but..... Start with the viewing distance. The maximum resolution resolvable with good eyes is given by the formula ppi = 1/((distance in inches x .000291)/2) - see link below. So for example at 12 feet, good eyes in optimal lighting, will resolve 1/((12 x 12 x .000291)/2) = 47 dpi. At that resolution your 16 ft wide image would need 9024 pixels - anything else is wasted. Unless you are decorating the inside of a lift, then typical viewing distance is 1.5 x diagonal - or in your example 18 feet. That would give a resolvable dpi of 31 dpi, requiring 5952 pixels. In short, at typical viewing distance - you should be fine with 6000 px to start. The link below may help you. Resolution for print viewing distance Dave
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