dynamic groups

[clog boy]

Groups are great... at last! I like to think of them as AutoCAD blocks, they're easy to create, once you change one instance they all change, and you can place just about as many instances as you want.

There's one thing that I don't like about groups though. Once you put something in a group it stops being flexible. You can only change in 'edit group' mode.
All of this sucks when you want to attach multiple roups to a grid. Say when you move the grid and some group members are attached to that grid, things simply break instead of flex.

Any thoughts about this? Group swapping is a big deal to us and one of the more important reasons to use them. But we need them to be flexible too. Suggestions would be greatly appreciated.

[Zoltan]

If the members of a group were allowed to flex and have relationships with the elements around them, it contradictory if there were multiple instances of the same group in different situations. By definition, all group members have to be the same.

The only solution would be a way to designate one of the group instances as the "master" that has relationships with the main model and the other instances are identical to it. But I can't see a whole lot of use for this.

[clog boy]

If the members of a group were allowed to flex and have relationships with the elements around them, it contradictory if there were multiple instances of the same group in different situations. By definition, all group members have to be the same.

The only solution would be a way to designate one of the group instances as the "master" that has relationships with the main model and the other instances are identical to it. But I can't see a whole lot of use for this.

Thanks, that's 'as is' indeed.
I think it would be a lot better though if instance parameters for group members could differ from group to group... but that would create a lot more new issues.
But how do Acad dynamic blocks work? In my opinion there are more similarities than differences between Groups and Blocks, and they managed to make blocks dynamic. They even embedded parameters and constraints. I would like it if groups could be engineered as a family without compromising it's BIM value.

[Zoltan]

Interestingly, Dynamic Blocks in AutoCAD are not actually different instances that all point back to the same definition. When you change a Dynamic Block, AutoCAD creates a new Anonymous Block that stores the definition of the block in its current state and that has a pointer back to the dynamic block definition.

From what I can tell, groups in Revit do not work like blocks at all in that they are not light weight references back to a master definition, but instead they are containers for a collection of elements that are managed by a relationship among them. For this reason, if you made a group that contained 100 chairs and copied that group 100 times, the file would not be any smaller than a file containing 10,000 chairs. In fact, the file with the groups would be larger because each group "container" is also a database record. Try it for yourself.

What would be interesting is if you could create a group that had parameters of its own and drove dimensions, reference planes and the parameters of elements inside of it, but then what you're really talking about is a Family. So to accomplish what you are talking about, you could just create a Generic Model family that contained nested shared families and it would act exactly like a group, in that the nested families would schedule independently.

[clog boy]

Interestingly, Dynamic Blocks in AutoCAD are not actually different instances that all point back to the same definition. When you change a Dynamic Block, AutoCAD creates a new Anonymous Block that stores the definition of the block in its current state and that has a pointer back to the dynamic block definition.

We need that :)


What would be interesting is if you could create a group that had parameters of its own and drove dimensions, reference planes and the parameters of elements inside of it, but then what you're really talking about is a Family. So to accomplish what you are talking about, you could just create a Generic Model family that contained nested shared families and it would act exactly like a group, in that the nested families would schedule independently.
Families are not going to work. they're not room bounding. You can't schedule the individual components as being walls, windows, floors or roofs. You can't make that wall out of four different layers and isolate just one layer for a production drawing. (we draw every wall layer individually)

Until Autodesk implements a 'dynamic block' type of group, we'll just have to make the best of what we can do today.