on Type and Instance

The concept of type and instance is a core Revit concept.  Some elements need to vary while others need to remain coordinated.  In conversations with customers I often hear that Revit could support the design process better.  This usually means moving things around, testing ideas, and swapping out content in an unrestricted manner.  Types add restriction yet if everything is an instance a lot of power is lost.  Lets explore this topic and start by reviewing what Revit offers now.

Curtain Wall can define Grid and Mullion patterns quickly by type.  Once a type is established you can choose to "un-pin" a sub-element to change its type, location or very existence.

These elements have a "Type Association" property which can be "Dependent" or "Independent".  In this case one may end up with a mix or type driven elements and others that can vary from other type instances.

Grids and Mullions can also be added to a Curtain Wall which has a pattern in its type.

In both the above cases you end up with a Curtain Wall that is mixed as to whether its elements are defined by the type or instance.

What about Structure?  "Beam System" has a command "Remove Beam System" which essentially makes all the beams behave as if they were placed manually.

 

Curtain Wall has a similar feature.   If you swap a Curtain Wall Type with a pattern layout defined for one that is undefined you will be asked if you want to keep the sub-elements as instances or delete them.

This is a little different from removing a Beam System as the type still exists yet its just set to "None".  The obvious question then is why doesn't Beam System have a layout rule option "None"?  ...an unfortunate inconsistency.  Beam system also places these properties at the instance level so it wasn't a type to begin with.  It would probably be good for Beam System to match curtain wall and while we are at it for Curtain Wall to have a "Remove Type Layout" command.

The work-flow I see missing from this is there is no way to convert an instance into a type.  Groups are the only thing I can think of.  You select some items and Group them which wraps them in type goodness.  The family editor also allows you to convert a parameter between type and instance.  What if you could mess around with Grids and Mullions on a Curtain Wall, select some and define it as a type layout once you arrived at a nice pattern?

Is fluid conversion between type and instance a step on the path to better supporting design?

...or

should there be a way to isolate and edit a type instance graphically?

...or both!  Thoughts?

-erik

Comments

[Chris Hubbard]

Erik,

I agree with you, but many of the other BIM software users point to this workflow as why you should use brand x. They are instance everything and use Find and Replace to coordinate and fix problems. People have asked for this tool in Revit for many years, and while I agree REvit does not "Need" this funcationality it would allow for people to make more Instance items and be able to coordinate. I envision a very flexible set of tools allowing everyone to work in their level of comfort and later lock down the model by converting to types and verifying coordination. Revit could check and verify that the items are all the same and flag items that are not compliant for futher review.

What do you think?

[Anthony Hauck]

It comes down to different needs at different times in the project. Im always very careful to not dilute principles that make the product strong but I get the feedback about the lack of flexibility early in the project.

[Rafael Alvarez]

I am all for making the design process more fluid. We should be able to insert objects that are type based, and then have the option to modify the object in-place. At that time the object, or aspects of it (ideal), become disassociated from the type definition.

This could be useful in creating canted or very complex walls for example. This is kind of how the roof and slab tools work now with shape editing. We should be able to see the parts of the object that do not follow the type definition, in a reveal mode much like the reveal hidden elements functionality. We should also be able to return the object into full compliance with the type with one click.

The reverse option is trickier but intriguing. It would be cool if one could make an in-place family and then convert it to a component family for starters. The next step would be to convert in-place families to system families. The problem here is that the converted object would first have to be compared against an existing type, the differences analyzed, and then the object is created as an instance of said type with in-place modifications.

Such a system would be incredible and would truly crush the competition because it would give us the best of both worlds.

Also, please develop a front end sketch mode for design that works as loosely as SketchUP and that allows you to draw in perspective. This is another wish that most of our designers have. If this workflow is not feasible then at least make some conversion tools for SketchUP that work with SKP links. This would enable the design process to move forward in parallel with the development of the BIM. Most times the design team and BIM production team are not one in the same. We end up having to delay the start of the Revit model until the design development stage to avoid rework.

[Michael Ruehr]

Eric
All your thoughts on this seem right on to me.
I am using Curtain walls for about anything …Railings, Windows, Doors, Kitchen Casework, General Casework, Sunscreens, Toilet & Shower Partitions, General Partitions….and more…
Because Curtain walls are a good way to order and organize design, and are easy to change.
We use as a Start a Type driven Curtain wall system for instance a Shop Front Window (vertical mullions every 1200mm CC)…
When Design evolves we change the wall to a non Rule driven one for easy Design changes changing Grit, Panels Mullions etc.
In the CD Phase we then make them into a Type via Groups as mentioned by you.
We exchange the Instanced Curtain walls with The Grouped (Type) Curtain walls.
We group them for 2 reasons,. For easy Change Propagation &Use in Phase Legends as Curtain walls don’t work with Legends.
So for me a more easy way to go back and forth between Type and Instance is great but it should not stop there…We should be able to go from a Rule drive curtain wall to a Instance driven then able to convert the whole Curtain Wall to a Family Type. More along the lines of a Loadable Family with the possibility of defining a Category as they are so very useful for so much more.
So instead of converting them into a group we could convert them into a Family Type without the Shortcomings of Groups and beyond the limitations of a rule driven Curtin Wall.

Ps. As one of the fierce Revit 2010 critics…. Congrats to the 2011 Release a truly great one…thanks for listening…

[Jeremiah Bowles]

Michael, you bring out a great point about using curtain walls for many items as it helps organize. As a Applications Engineer for a reseller we get the bulk load of criticism about why Revit can do something they want in one area and not in another. Why can't tools have the ability to cross object style. For example, why do you need to take a curtain tool and use it for railings why couldn't the tool be used or custom defined for multiple uses?

Another example,we can do awesome things in Revit Massing that SketchUp can't touch but we are limited to items to convert to. For example, I can do a wall from a mass form but I can't do a "ceiling" from a mass form, I need to trick it and make it a floor or roof item and rename wall styles, materials etc. to manage things.

[Jeremiah Bowles]

Yes Raphael, Revit does massing, and has a very functional work flow that takes you beyond what SKP can do in many ways. For example in early design we can: do detailed rough QTO (Quantities), presentations, Area Plans, Detailed Analysis, Program Analysis etc. One of my clients (former teacher for SketchUp and big fan was impressed how far Revit's capabilities were in comparison to SketchUP in early conceptual design and how easy to learn the tools were also. The most important part of design is iteration and alternatives. This workflow works seamless especially after a design is selected, the transition into DD is virtually seamless as placeholder geometries are transitioned to actual as items are specified. There is no loss in man power or Model asset re-created.

[Glenn McGuyre]

Did someone say In-Place Families? Not to start a rant about it but, don't we all think that In-Place Families should be convertible to a true Family Type based object? In-Place Families are type based to the extreme, every time you copy one it makes a different In-Place Family object, that is insane...