SecretWeb = Wayne.
Some people have reported some problems while visiting ATS. So, here is the Post :

"Possible Causes for the offsetting
1 â??He eyeballed the positions and thought his eye was â??so goodâ?? he didnâ??t need to use proper alignment tools (or didnâ??t know how to.) (This is more common than youâ??d realise amongst modellers of all levels.) I wouldnâ??t give this the best chance of being the reason and included for completeness, although itâ??s obviously a possibility.
2 â?? He forgot to group all the geometry parts and missed some while move / scale / rotate.
Explanation of â??groupingâ??
Models often are comprised of multiple parts and as such the ability to group these into a temporary unit is found in nearly all major modelling applications. This allows the modeller to transform (a fancy name for moving, scaling or rotating) the model without fear of parts ending up out of alignment or being left behind by accident.
Chances are that if this is the reason then he tried to put them right or simply didnâ??t spot it until it was too late. He simply didnâ??t get it as spot on as if aligned using the proper solution.
3 â?? A conscious decision as he thought it would add a â??less CGIâ?? subtle effect instead of perfect perfection. This is misguided as if aliens are anything like our engineers they donâ??t like â??unpredictableâ?? or â??randomâ??. So the chances of this one are remote as a reason but possible none the less.
4 â?? If the craft was parented to a null object to make it easier to move about (or he could have animated the shots and taken single frames to composite into different shots later), unless the centre pivot was in the right place it could cause behaviour such as this when it was moved scaled or rotated.
Explanation of a â??nullâ??
Think of a null object as a non renderable (i.e. not visible in renders) simple cube (although other shapes can and are used) that us used to link the geometry, lights, bones or camera etc to.
5 â?? Not being â??groupedâ?? (or grouped with not all the parts in the â??droneâ?? in the group) chances are that he has accidently rotated the model by a degree or two. This explains why some â??screwsâ?? are further out the further towards the edge they go. Out of all the reasons, this would be my bet. â??User errorâ??.
Those are the reasons off the top of my head that are probably causes of the misaligned screws. This misalignment obviously produced some problems with shadows being deeper and slightly larger around the worst of the misalignments. Its worth remembering that a 'center pivot' is not always in the center of an object and that they'interact at times when mutiple grouping or linking is used if not correctly handled.
Wayne... "