Sloped Ceiling Patterns vs Groups vs Levels

[jsnyder.68308]

We have an odd "feature" that seems to have popped up. The project is a large lower education building with 6 classroom pods that repeat and step down the site. Each Pod is on a different level. We have placed sloped ceilings on the underside of the sloped roofs - the ceilings have a 2'x6' model surface pattern applied to the material. All of the ceilings for the pod have been placed in a model group, which is then copied down the line in each pod. The problem is that as the group instances step down the site, the location of the ceiling grid pattern changes. I want the grid loaction to be exactly the same in each group instance, regardless of its vertical location.
I understand what is happening, but I do not understand why. The ceiling grids in the groups appear different because of their vertical location/associated level? I am curious whether this is a bug or intended behaviour. If it's intended, groups are not much help to us in this case. What are we missing?

[wmullett]

If these are groups, you might try locking the model grid with a dimension in the group definition.

[Scott Womack]

Your issue lies alot deeper than you realize. I doubt that my explaination will make total sense, but here goes. When you are placing a ceiling in a group, it is an instance of the other ceilings in a group. Since they are all instances of one another, the material pattern on these ceilings is essentially a continuation of the same pattern. Because of this continuation, they all use the same "starting" point, and as you are copying them, it makes the pattern appear to be "shifting".

To do what you are whating, you'll have to remove the ceiling from the group, and deal with them independantly.

[jsnyder.68308]

Your issue lies alot deeper than you realize. I doubt that my explaination will make total sense, but here goes. When you are placing a ceiling in a group, it is an instance of the other ceilings in a group. Since they are all instances of one another, the material pattern on these ceilings is essentially a continuation of the same pattern. Because of this continuation, they all use the same "starting" point, and as you are copying them, it makes the pattern appear to be "shifting".

To do what you are whating, you'll have to remove the ceiling from the group, and deal with them independantly.

Oh, it makes perfect sense to a computer program, I suppose. It is clear that all the group instances are using the same "snapbase" point, in another parlance, to create the patterns. Thank you for confirming my suspicion.