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How does manipulating the Project Base Point and Survey Point affect the Project(05 of 10)

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If you're using the default templates provided by Autodesk, then in any plan view after unhiding the SBP & PBP, you can observe that both PBP & SBP are at the same location and overlapping each other. If you select either of the base points, you can see the information of the Point and also a Gizmo that allows us to move the selected base point in the 2D plane. But the orientation of the Gizmo for both the points might be different depending on the Orientation of Project North and True 

North.

Before moving either of the points, notice a clip shaped icon when you select either of the points. This icon denotes the clipped/unclipped state of the respective point, which says how moving the point would affect the entire project.

Clip/Unclip the Base Points
If you move the points using the Gizmo, you'll notice that moving the Project Base Point moves the whole project i.e., all the elements modeled, while moving the Survey Base Point doesn't do anything. But moving either of the points affects the entire project and is not recommended until you're very comfortable with it and understand the concept of the coordinate system in Revit.

Let's take the example from my previous post(02 of 10) to better explain this.

Click here to see the example

To better understand what a project base point is, let's assume we're creating a 3D model of a building on the top of a Cardboard/Canvas with a size of "100cm  X 100cm" that is placed on a table with a size of "200cm X 200cm" whose height is 75cm from the ground placed exactly at the North Pole. 

Let's consider for this model, the Center of the table to calibrate the physical/actual location on site, the Survey Base Point would be N=0, E=90, Elev 75cm. So if you change the value of survey base point, it means that you've moved the table to another location on the earth.

And if we consider the Project Base Point to be the bottom-left corner of the Cardboard/Canvas whose values would be X=0, Y=0, Z=0. You can change this point by moving the Cardboard. All the model elements location is relative to that point. And if your model is a combination of several sub-models(which you created separately) that you combined(linked) to make the whole model(Revit links), then you can say the each of the sub-model has their own Project base point (0,0,0), but relative to the main cardboard, they each have their own different points they need to be placed on, which is the Shared Coordinates(explained in detail in a separate post).


Note: The symbols, X, Y, N & E in the above example are custom symbols and can be changed to anything in Revit. The default symbol for both points will be N & E

Moving the Project Base Point

There are 2 ways of moving the PBP.
  1. Moving the PBP in its clipped state:
    Clipping the PBP can be assumed as gluing the model elements to the base cardboard. This method is used when you want to move all the elements in your projects relative to the PBP i.e., this will keep the Table at the same location but all the elements along with the base cardboard is moved. So the Origin(X=0, Y=0, Z=0) of all the model elements is not changed.
  2. Unclipping the PBP and moving:
    This method is used when just you want to move the origin of your project i.e., this will keep the Table and all the model elements at the same location but only the base cardboard is moved. So the Origin(X=0, Y=0, Z=0) of all the model elements has been moved.

Moving the Survey Base Point

There are 2 ways of moving the SBP.
  1. Moving the SBP in its clipped state:
    Clipping the SBP can be assumed as gluing the base cardboard along with the model elements to the table. This method is used when you want to move all the elements in your projects relative to the SBP i.e., this will move the entire table along with all the elements & cardboard to a new location. So the Origin(X=0, Y=0, Z=0) of all the model elements is not changed.
  2. Unclipping the PBP and moving:
    This method is used when you just want to move the SBP of your project i.e., this will keep the base Canvas and all the model elements at the same location but only the Table is moved. So the Origin(X=0, Y=0, Z=0) of all the model elements is not changed. This means that the relative position of all the model elements w.r.t the PBP(Origin) has not changed, but the relative position of the PBP itself w.r.t the SBP is changed.
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