I once asked why the texture map vertices were labled u,v,w and was simply told, "...because they are the three letters preceding x,y,z... When we referred to UVW or IJK, it was assumed that we were going to evaluate the point to a different datum, (not the datum from the RSP), driving towards the point along the described vector. It was to make sure that the aircraft part was in the correct position on the aircraft and to the aircraft.When we used XYZ to describe the coordinate system, we were making it easier to interpolate the point to the ruled surface patch coordinate system and manufacture the aircraft part. Many machining stations back then couldn't drive along a vector so the data had to be in XYZ coordinates. It also made it easier for a machinist to setup his station since the datum came from the part itself. You didn't have to create a point in space 30 feet away to make the thing.It was also a naming convention used so you could immediately discern the intention of the data. So if you were walking down the flight line and you found a piece of paper on the ground that had XYZ data then some machinist somewhere must have dropped it. If it had UVW or IJK data it must have been lost by an engineer.UVW could have been named PPM..short for Peter Paul and Mary...but that wouldn't be technical enough for us nerds...although quite nice to listen to. And whoever told you it came before XYZ, was not speaking with a forked tongue...it's the truth :)Mark

Very interesting comments.I've seen this effect many times in FS and other 3d drawing programs, and had always believed it was caused by minute errors in the geometry due to the 'finite' nature of the maths.I hadn't previously considered the wrap around effect of the 3d engine's texturing unit.

Very interesting comments.I've seen this effect many times in FS and other 3d drawing programs, and had always believed it was caused by minute errors in the geometry due to the 'finite' nature of the maths.I hadn't previously considered the wrap around effect of the 3d engine's texturing unit.

There are several ways of UVW Mapping available: planar (flat photograph), box (all six sides pre-mapped), and cylindrical, among a few others that truly aren't useful for FS work.Some modelers (including ACES in-house default a/c) use the cylindrical UVW Map. This form of mapping effectively "flattens the curved surface while preserving the spatial dimensions of the underlying polygons." Unfortunately for the texture artist, it likewise make the creation of artwork more difficult. Since large airliners rarely have fancy cheat lines it isn't too much of a challenge. For private aircraft that typically have lots of cheat lines, it's a nightmare!Planar mapping is what I typically use. If there is detail that needs to be "painted" on the top or bottom of the fuselage, where the left and right planar maps meet, then I will select those polys and create separate planar UVW Maps for those areas.