Site Model, Linked File, Shared Cooridantes...again (my apologies)

[amjones]

I am loosing it perhaps. I have read countless threads on how to get this right and I am missing something crucial I think.

I have a building model that has the survey point (SP) and the project base point (PBP) set up to correspond to how I though they need to be based on the threads I read. Both were moved while pinned. Nothing is linked yet. The SP is 161'-6" below the PBP and a certain distance west and south. Project north is 38.7483 from true north. The Survey Point is at 'Sea Level'. I though it need to do this so that my topo link would come in correctly in regards to sea level.

I have a survey file with contour lines in ACAD that I essentially hand made. It has polylines at certain levels in regard to sea level.

What are the correct steps to get so I have linked topo model that I can update that links to my Revit model? Am I going to deep having the SP and PBP in different locations? To be honest the difference between the SP and the PBP is (apparently) lost on me…why am I moving the SP it in the first place? I generally understand the Pinned vs Not Pinned movement of each but how then that relates to where and how linked files comes in is got me turned upside down.

Any help would be greatly appreciated. Hive read and reread this post: http://forums.augi.com/showthread.php?t=105452

Thanks,
Drew

[amjones]

I should clarify, the site model starts and ends in our office...the topo model will not be updated by our civil engineer or provided to him. The grade changes will be made by our office based on his drawings.

Thanks,
Drew

[amjones]

OK,

I think I have something figured out. I think I set up my Survey Point and Project Base Point incorrectly in my model file. This is what I have done thus far:

1. Unclipped the Project Base Point and move it back to the startup position, changed it's elevation to 0'-0" and it's true north back to 0.0 degrees
2. Moved the clipped Survey Point back to the startup position (dragged it to the relocated Project Base Point)
3. Moved the unclipped Project Base Point (in plan only) to my desired location...then clipped it.
4. I moved the clipped Survey Point (again via dragging) to the new Project Base Point location.
5. I changed the clipped Project Base Points true north to 38.7483.
6. I then move the clipped Survey Point orthogonally from the Project Base point 154'3 to the left and 72'4 down...this represents the location of the site boundary corner.

So...now the Survey Point and the Project Base point are in the correct relation to one another in X and Y dimensions and are both at 0'-0" elevation-wise. My project is modeled with its first floor at 161'-6" above sea level (0'-0") and all my level and datum’s currently report heights from the Project Base Point (Project)...at current the value would be the same if the datum was to report the Survey Point (Shared) because they are at the same level.

So, the question is...do I unclip the Project Base Point and move it up 161'-6". This would give me the datum levels related to the Project Base Point (Project) to be 0'0" for the first floor, and I could still spot report elevations from sea level (Shared) if I choose to. I would then clip the project base point so I could shift the build around via it.

I hesitate because this was the exact relationship I had pervious when I was sure I had something wrong. So should I move the Project Base Point up or not? And how will doing so (or not) affect Revit links of my topo or other consultant files which are not linked yet.

Thanks,
Drew

[amjones]

All,

The answer is...I can do whatever I want with the Project Base Point in the building model. It has nothing to do with how things are imported. My main problem was in the site model in that I inherited cooridantes from my linked buildign model, but that left the sites project base point at 161'-6". My site dwg then linked in to the sea floor level, but all my derived toto points were bing measured from the project base point and it messed up the topo lines because everythign was 6" off a full foot incriment. alos had an issue with linkiogn the DWG with Shared coordiantes. I kept usign origin to origin and then movign it around manually. As soon as linked it to Sea Level uisign Auto Shared Coordiantes it did everythign i needed.

just to clarify now: Origin to Orgin is only in regard to the interal Revit Coordiant system...right? I had been under the impression that Origin to Origin had soemthgin to do with the my moved Project Base Point. I now belive it does not.

Thnaks,
Drew

[iankids]

Hi Drew,

You are totally on the right track.

By using a combination of Shared and Project Levels you can create a project where you can report either the absolute level, as shown by the land surveyor, or the levels relative to the proposed ground floor as you wish.

The topography is always modeled to the absolute level as nominated by the land surveyor.

You would then either create levels to represent the levels of your proposed building or move existing levels accordingly if they are already created in your template file.

Having positioned the levels at the correct height relative to the topography, they are set as a shared level.

Then Manage Tab - Coordinates button - Specify Coordinates at a point. Select the point at the end of your ground floor level - must be the point and not the level line itself, change the elevation of this point to set it a 0.0

Use the Match type command to set all the other levels to share level type.

The spot elevation tool can be set to project level and it will report the actual level as per the land surveyors info.

I have attached a few screen shots to illustrate the above.

Hope it helps,


Ian

[amjones]

Thank you for the reply...I had a feeling as I posted my original post that two things would happen:

1. I would not simply stand by and wait for a reply and would likely answer at least some of my issues myself with trial and error and error and error and trial

and...

2. Someone would eventually round out my flailing with some good solid information.

Long live Augi....and thank you very much Ian.

Drew

[patricks]

What I have been doing is starting a new file, link in CAD survey, rotate it to my project north setting, and then acquire coordinates from the survey. Then I create the existing topo surface in that file. I also verify that the topo lines in the CAD file and the toposurface I just created is the correct elevation above 0'-0" in that file (200-300 feet in this area usually).

Then I link in my building file (center to center), position correctly in the X, Y, and Z directions (move and rotate it in plan, move it up in an elevation view), and then I PUBLISH coordinates to that building file.

Now when I go back to the building file, I link in the site file using shared coordinates, and it comes in at the correct location.

I haven't had much experience moving project and survey points around, other than last year when I tried it and had problems. You can see my posts about it in that thread you linked above, but to tell you the truth, I can't even begin to tell you what all I did to get it working correctly.