Surveyor - Project POINT - How to control this weirdo?

[Anonymous]

Hi,

-put DWG Stations in Revit

-Acquire Coordinates

-Define Project point at certain spot on the imported or linked CAD

-Project point is now at coordinates X, Y, Z that is not ZERO,

-Surveyor point is at Zero. 

ISSUE:

New unmovable and unclickable Point (Pokemon in text forward) appears on random at random, what is that, why does Dynamo (when placing families) read it as 0,0,0 and doesn't use my Project Point as Zero.

I want for Dynamo to read Project point as 0,0,0. 

Even if I use SPOT COORDINATE at Pokemon, it shows some random coordinate value, different to ZERO of course. 

QUESTIONS:

1.Is there a way to move Pokemon to Project point so the Project point is 0,0,0 to Dynamo?

2.Is there a way to move Pokemon to Site point so it gives the value of N:0 / E:0 aka. Coordinate of Project point on the left would be reachable by the same coordinates input in Dynamo. 

Thanks! 🙂 

[Sean_Page]

That is Revits internal Origin that cannot be manipulated in anyway, and to that end also doesn't really affect anything either. If your SP and PBP are correct you've got what you need!

[Anonymous]

I disagree on the statement that it doesn't matter, which is why I made this forum post. @Sean_Page 

Let me try and clarify:

When I place a Revit element (Family instance) on 0,0,0, (using dynamo) it will put it on internal 0,0,0 (randomly distanced from either Project or Surveyor) which is a random point coordinate and the coordinates I got from my 3d polyline  for placing elements are as of that moment invalid. 

So no, if I want my Project point to be on some distance away from Survey, I want Dynamo to put elements on either:

1. 0,0,0 as Project point 

2. 0,0,0 as Surveyor point

Not some third invisible non-movable randomly spawned point Revit uses for who knows what.  

[RPTHOMAS108]

The internal system is the only system that matters and there is nothing random about it. It is the only system the API uses and I assume likewise Dymano. You are expected to convert from the internal system to the survey coords system or the project coords system by creating a transform object (from the offsets and angle) and using Transform.OfPoint.

The below deals with internal to survey, internal to project is similar but there is no rotation involved and the offsets for that can come from the IsShared = False BasePoint object within the project document. If you want to convert the other way (survey to internal or project to internal) then you just invert the transform (Transform.Inverse).

https://thebuildingcoder.typepad.com/blog/2012/06/real-world-concrete-corner-coordinates.html

Here is some information about Transform.OfPoint. I assume to Invert the matrix they make it 4x4 with 0 0 0 1 for bottom row, this isn't really clear in the documentation???

https://knowledge.autodesk.com/support/revit-products/learn-explore/caas/CloudHelp/cloudhelp/2014/EN...

[Anonymous]

At start Internal, Survey and Project is at 0,0,0.

I move Project to certain point (XYZ) and import DWG (just lines of stations for the road). I place DWG so that 0,0,0 is on Survey point, and the point on DWG that would be the middle of the structure is on Project point. 

Tried acquiring coordinates from the DWG directly, same thing happened.

Unmovable internal point then MOVES automatically to a random place (A,B,C) which is (D,E,F) vector moved away from Project point and (A,B,C) from Survey Point, with a weird connection to dwg - it gets placed on the middle of the screen when you would go into that dwg and doubleclick middle mouse button, but what does that have to do with anything, we do know that that point will be used as zero by API, Dynamo etc, so no thanks. 

So I disagree that there's nothing random about it and I do not understand the statement that this is the only point that matters (and to make it not flexible).

As for the links, does the average Revit user need to be a programmer to be able to set up a coordinate system in Revit? 

[RPTHOMAS108]

The internal system doesn't move the survey and project base points move relative to it. So no matter what you do the internal system never moves. That is why I say it is the only thing that matters, not because it is the only thing we care about but because from an API perspective it's the only system that can't be changed by the user. Even rotating project north (not true north) moves the elements of the model about within the internal system not the system itself. This is why it is inadvisable to rotate project north of a very developed model.

I'm not sure about how acquiring coordinates from a DWG affects how the position of the project and survey base points move relative to the internal system. However I know one thing for sure they change and the internal system doesn't. Try outputting the key aspects before and after to understand i.e. transform origin and basis of the base point objects along with their parameter values E/W, N/S angle from north etc. Place a circle at the internal origin and tell me the circle no longer encircles it after the change.

As a user I've never struggled to link Revit files together by a relative position and set up an overall survey position for them. This is seamless since it's something where Revit is doing the work for you. However as a developer you get all that a Revit model actually is in terms of the relative positioning system (internal system and transformations from such). Not so long ago in Revit an end user didn't even have the cursor for the internal system shown, imagine that mystery. There are functions in the API for linking models by shared position and aquiring coords etc. if that it your need here.

[RPTHOMAS108]

Below is some further explanation of how changing the base points has no effect on the internal system and it may help understand the changes that take place. I'll use SBP and PBP in place of Survey Base Point and Project Base Point.

In the first image I have moved PBP 10' east and SBP 20' east. When survey point is clipped you are moving the survey origin with the base point. Within Revit lookup we see Positions of 10 and 20 from the internal origin. Shared position can also be seen but that isn't the internal system.

In the second image I have rotated angle to true north on the PBP and it can be seen that the SBP takes up the position expected on screen. The internal system is still parallel to project but the shared system is now at 45 degrees to project and internal. Also can be seen that the position property in RevitLookup is measured from the internal system (same as before for PBP now 17' & 7' offset for SBP). You can also see that PBP 'SharedPosition' property measures as -10' down the diagonal.

Lastly I unclip the SBP and move it 5' towards PBP. You can see that shared origin remains where it was (the PBP and SBP give the offsets from it you would expect). The 'Position' property is still measured correctly from the internal system which has remained consistent throughout.

So in summary if you want to convert between survey coords and internal coords use the approach from the link in my initial post. If you want to convert between project coords and internal coords then set up a transform based on the Position property of the PBP (noting that the project system is always parallel with the internal system). My further observations tell me that acquiring coords from a DWG doesn't change the positions of the base points themselves just the offset and rotation from true north parameters.