Clipped or Unclipped Project Base Point

[tzframpton]

I'm trying to accomplish something and I think it has something to do with the Project Base Point being Unclipped. Here's the issue:

My current Project Base Point has an elevation of 427'-0". My Finish Floor Level is 525'-0". This causes anything relative to the Project (such as exporting the Model to DWFx, or using the Spot Elevation tool) to read a measurement that's 2'-0" lower than what I need, due to the 98'-0" difference in the Project Base Point elevation in relation to the Finish Floor Level elevation.

Upon my investigation, I'm wondering if all I need to do is Unclip the Project Base Point and adjust the Elevation to be 425'-0", to give an offset of 100'-0" in relation to my Finish Floor Level. I am also working with other Revit Models linked in from our other offices, so I don't want to screw anything up.

Any thoughts on how I can accomplish this? Thanks in advance.

[joss]

im exactly on the same problem right now. hope someone can help us out.

[snowyweston]

Why would you move it to 100' offset? If you want your project base point to be your FFL, then set it to be FFL - then project-based elevation query annotative elements (spot elevations, spot coordinates w/ Z, and levels) will all read from that single "0" when needs be.

I make sure when I do this I have a spot elevation tag type of each (shared/project) placed on the FFL level and note what happens (to their Z-values) when I adjust the project base point (clipped or unclipped, it's worth "doing" both just to get an idea of the mechanics of it all)

That said, if you are working with other models, from other offices, you will want to do this in a coordinated manner - there may be a reason why your project base point is set to where it is, and you don't want to go messing with it if that's the case. That's not to say you'll potentially upsetting the survey base point (that may or may not be shared with these other models) but it might be something in the way the project (entire) is planned for documentation.

[tzframpton]

Why would you move it to 100' offset? If you want your project base point to be your FFL, then set it to be FFL - then project-based elevation query annotative elements (spot elevations, spot coordinates w/ Z, and levels) will all read from that single "0" when needs be.

Weston, thanks for the reply. This Revit model that we're working on was 70% complete from another architectural firm. It was pulled from them and gave to us for whatever reason the building owner had. All designing disciplines and general contractor on board agreed to use the existing base point to minimize issues and confusion.

I make sure when I do this I have a spot elevation tag type of each (shared/project) placed on the FFL level and note what happens (to their Z-values) when I adjust the project base point (clipped or unclipped, it's worth "doing" both just to get an idea of the mechanics of it all)

This is a great tip. I did exactly as you have suggested and I played with the Project Base Point elevation. I see the differences in how it affects the elevation displayed in comparison to the Relative versus the Project based Spot Elevation Tool.

That said, if you are working with other models, from other offices, you will want to do this in a coordinated manner - there may be a reason why your project base point is set to where it is, and you don't want to go messing with it if that's the case. That's not to say you'll potentially upsetting the survey base point (that may or may not be shared with these other models) but it might be something in the way the project (entire) is planned for documentation.

After playing around with the Project Base Point being clipped versus unclipped, I decided to simply leave it alone. I was trying to do this out of convenience but I have came to the conclusion that clipped versus unclipped isn't doing what I was expecting it to do. If I tinker with this and sync to my Central I think it'll wreck shop with the other designers on board. Thanks again for the tips and clarification. It is much appreciated.

[DaveP]

Snowy, just curious what the convention is in the UK.

It's not universal, but a lot of firms in the US use 100'-0" as the First Floor Level.
Yes, it might be more logical to call out the First Floor as 0'-0", but then Levels below the First Floor end up using negative numbers.

Which is more common outside the States?

[Twiceroadsfool]

Snipped from a Blog... I believe Teresa Martins from Ideate, byt i may be wrong.

Project Base Point (PBP): Clipped
Move the PBP
PBP values change
Project-based spot coordinates don’t change
Model elements “move” relative to shared coordinates
Moving a clipped PBP is the same as using Relocate Project. That is, the model elements maintain their relationship to the PBP, but the relationship of the PBP
to the survey point is changed.

Project Base Point (PBP): Unclipped
Move the PBP
PBP values change
Project-based spot coordinates change
Model doesn’t move
Unclipping the PBP essentially detaches it from the internal project origin. Moving the unclipped PBP is really only used to affect the values
reported in spot coordinates set to the Project origin base. It does not have any effect on exported files.

Survey Point (SP): Clipped
Move the SP
SP values don’t change
Shared spot coordinates change
Model doesn’t move
The clipped survey point represents the origin of the shared coordinate system. Moving it is the equivalent of setting a new origin point.
Use caution if you must move the shared coordinates origin, especially if linked models already exist in which the shared coordinates have
been synchronized. In such a case, each linked model must be opened and manually reconciled with the model in which the origin has changed.

Survey Point (SP): Unclipped
Move the SP
SP values change
Shared spot coordinates don’t change
Model doesn’t move

[JeffH]

It's not universal, but a lot of firms in the US use 100'-0" as the First Floor Level.

My office used 100'-0" as the first floor datum. Of course I was a practicing Architect in Minnesota just like Dave so maybe I am not a good indicator. That is just how it was done in 2 firms in Minnesota.

[cliff collins]

This is always a difficult subject.

See the attached PDF, which is the best explanation I have come across.

( Hats of to Paul Aubin.)

[need4mospd]

Snowy, just curious what the convention is in the UK.

It's not universal, but a lot of firms in the US use 100'-0" as the First Floor Level.
Yes, it might be more logical to call out the First Floor as 0'-0", but then Levels below the First Floor end up using negative numbers.

Which is more common outside the States?

I've either used elevation above sea level or 0'-0" first floor in the four different firms I've worked at in Houston. 100'-0" would get confused as elevation above sea level if we used it around here. We just go negative for lower levels if we use 0'-0" first floor, not a big deal for me.