You can check out Ninja UV. You can map to a specified pixel ratio. Scale to a pixel ratio. Plus alot more tools http://www.creativecrash.com/maya/marketplace/scripts-plugins/texturing/c/ninja-uv--2
Often when I map I use the planar projection and insert what numerical value I want to the height and width to be to maintain consistent shells. Currently, I just copy and paste my value into both inserts but surely there has to be a faster way to do this? Is there a tool or script that allows me to define my value…