color printing multiple maps

Hello,

I am prepping models for color printing, many of which have multiple texture maps. Shapeways says under their color printing guidelines that -

"You can use more than one texture map on your object, but the maps are not allowed to overlap – the printer cannot figure out which texture to print in that case."

Is this referring to that if there are multiple maps, that the UVs must be in seperate quardrants?? I am having a hard time making sense of this, and just wanted to verify what it means before sending out objects for printing.

Thanks for your help!!
mike

I have a guess. looking at the videos of the color printing process, I see that each slice of the volume is outlined in a stripe of color. It looks like they thicken the line to avoid any gaps or inconsistency at the edges. If you had two nearby color surfaces (lines in 2D), "thickened" like that by the software, they would overwrite parts of the previous ones (in memory). The order that they are written would change from slice to slice, creating a mess of color garbage when printed in 3D.

It's like the similar effect created when two polygons are placed nearly on top of each other in a 3D scene, or when zooming to extreme scales. The renderer can't figure out which one is in front because of limited precision in depth-sorting.

If you must have two maps touch, try to have them be the same colors where they contact, or at least try to cross them at as close to a right-angle as possible.