I discover something really strange when I used the Dynamo nodes “coordinates.survey” and “coordinates.basepoint” VS the results i got from BuiltInCategory.OST_ProjectBasePoint and BuiltInCategory.OST_SurveyPoint .

It’s hard to say what exactly is happening without knowing what all those custom nodes are actually doing. Revit tracks and returns coordinate points in different ways. I’m guessing you’re seeing the difference between the coordinate values for the points and the relative offset of the points (from the internal origin).

the one from GeniusLoci and mine represent the exact location in the projet.
i just dont understand the ones from the Dynamo.
the other from archilab must be a unit issue.

“Exact location” meaning what? Position based on the internal coordinates? Those values may not be the same as the coordinate values for those points. There are technically 3 different coordinate systems in a Revit model so there are technically 3 different ways to describe those location points.

yes i know
the project base point in that case are the same as the internal one.

what im trying to say is if i can get the project and survey points through BuiltInCategory.OST_ProjectBasePoint and BuiltInCategory.OST_SurveyPoint, why there is a different value from others nodes?

It looks like your Project Base Point may be located at the internal origin but with specified coordinates. So your PBP is at [0,0,0] (according to internal coordinates) but with N/S, E/W, and Elev values of [10000,6000,0] (Revit reads this as an internal transform and that’s why the values are negative). Dynamo uses the internal coordinate system for everything so the values you get from the OotB nodes are their locations in the project. The values you get through the API are their specified coordinates. You can see from the different values you’re getting between nodes that one is just the difference (transform) from the internal coordinates. I think you’re right in that the archi-lab node is a units issue.

In one case, these are the values of the point coordinate parameters, such as “N/S”, “E/W”, “Elev” (it may be specified in Manage->Coordinates->Specify Coordinates at Point). Otherwise, these are the values of the position of the point relative to the internal origin (0,0,0)