True north, shared coordinates & linked dwg site plans

[Martin P]

our engineer and landscape architect are doing the car parking etc for a scheme I working on. I am struggling to get to grips with how I control the location of the dwg site plans I link in relation to my revit model, I have done the tutorails on shared coordiantes etc, and must admit the whole method confuses me, especially with the true north thing I am afraid it is lost on me, I just cant get my head round it.

Basically all I want is to get the site plan to come into revit in the correct location, using the auto insert with coordinates. my autocad files are in the correct world location. How do you do this?I dont want to move my autocad files in autocad, and dont particularly want to be manually rotating and moving them in revit.

I cant help feeling that in trying to keep things simple by not using a coordinate system, Revit has become more difficult and confusing to use when it comes to this type of thing, or maybe it is easier and I just dont get it?? :?:

[Martin P]

our engineer and landscape architect are doing the car parking etc for a scheme I working on. I am struggling to get to grips with how I control the location of the dwg site plans I link in relation to my revit model, I have done the tutorails on shared coordiantes etc, and must admit the whole method confuses me, especially with the true north thing I am afraid it is lost on me, I just cant get my head round it.

Basically all I want is to get the site plan to come into revit in the correct location, using the auto insert with coordinates. my autocad files are in the correct world location. How do you do this?I dont want to move my autocad files in autocad, and dont particularly want to be manually rotating and moving them in revit.

I cant help feeling that in trying to keep things simple by not using a coordinate system, Revit has become more difficult and confusing to use when it comes to this type of thing, or maybe it is easier and I just dont get it?? :?:

I can do this type of thing with autocad with my eyes closed, so I am trying to think in terms of UCS, this may be what is putting me wrong - but I cant help doing so....

[sbrown]

Unfortunately as I understand it the shared coordinates don't help on importing dwgs, they help with importing linked rvt files, I maybe wrong, if so I'd like to know, because we struggle with imported sites. Anyway, I can help you slightly.

1. Link the dwg, don't worry where it goes, just that its the right scale. NOte that if you select a scale other than automatic, ie feet. then close and open the drawing and manually reload the dwg, it will scale back to its original size messing you up completely, If you need to manually reload you must go back to the import dialog and change the scale factor to the same as when you imported it, this can get very problematic with lots of dwg inserts.

2. move the site plan to your model and rotate your site plan to the model(project north).(note first determine the angle between your project and the site plan, you will need it in a minute)

3. click tools>locations and coord>rotate this project/true north, enter the angle you got in the previous step, visually you will see nothing, now go to view properties and at the bottom, change to true north, if it rotated the wrong way, undo and put a - in front of the angle.


Now everytime the engineers make a change you will be allright.

[David Conant]

You can use shared coordinates with imported dwg files as well. Start as Scott described by importing the dwg and positioning it correctly with respect to your current project. Then:

If the world coordinates of the imported dwg represent true North and global location you want to Acquire Coordinates from the dwg. This will creates a shared coordinate system that uses the dwg's 0,0 as origin and Y axis as True North.

If your current project's north is also True North, you want to Publish Coordinates. This will create a new UCS in the linked dwg who's origin is the current RVT file's origin and Y axis represents the current project's north based on the current position of the link in your project. Note: this action will actually modify the dwg file.

[Martin P]

Excellent!! thank you for the pointers - I will go off and do ihave a go, sounds pretty simple now:oops:

Revit adds a new ucs to dwg files :!: thats something I'm going to have to tinker with.....

[sbrown]

David,

is this process documented anywhere and does it still work if you need to scale the drawing?

Again in our typ. process we first have our bldg layed out "project north"
then we import the dwg and scale it up 12 times or chose feet(for whatever reason thats the way our civil drawings come in). then we move and rotate it to "project north", then rotate the project. Where in this process would I aquire the coordinates and do as you described. Now if I publish them. do I need to send the civil background back to civil?

[David Conant]

We are working with our documentation team to make sure that the process described is fully documented.
Scaling the DWG during linking will not matter. In your process, you should Publish coordinates to the dwg after you have moved and rotated it into the correct position. After publishing, you should send a copy back to your consultants. They will then have a file that contains the new UCS representing the shared coordinate system.

[sbrown]

Thanks, very interesting.

[David Conant]

After thinking about your process a bit longer, I think you ma ywant to Acquire coordinates from the dwg file. Do this if the WCS of the dwg is based on real world location coordinates and True North. Acquiring the coordinates will dreate a shared coordinate system in revit vbased on that in the dwg. In that case there is no need to send files to consultants

[sbrown]

do you need to aquire them before you rotate the plan(dwg) or does it matter?

[JamesVan]

Martin,

Have you created a 'round trip' of the RVT data back into DWG for your consultants? We did some testing with this and found the best way is to Link the DWG's as Origin to Origin, then adjust our RVT model to the linked site plan. That way, when any DWG's are exported and xref'd by your consultants, they will still align with the site data in AutoCAD.

BTW, this was tested before the appearance of Shared Coordinates so Dave Conant's advice will most likely be the most accurate (from the horse's mouth, so to speak... :wink: )

[David Conant]

Position and orient the dwg before acquiring coordinates. If you have to make further modifications after acquiring coordinates, use the Relocate This Project and Reorient This Project/True North commands under Tools|Locations and coordinates. This will reposition your Revit project with respect to the dwg and remember the changed relationship to the shared coordinates.