Acquired Coordinates in Revit don't match Autocad survey

[Anonymous]

When I click ID on a point in the Autocad survey file it shows the correct coordinates based on the Indiana State Plain system we are using. I link the file into a brand new clean Revit file then click on "Acquire Coordinates". If I do a spot coordinate for that same spot I checked in ACAD, the coordinates do not match...in fact its exactly double in both directions.

I drew a line in CAD from the origin to a point on the plan, saved and reinserted the model into Revit. When I check the coordinates initially in Revit they are correct but when I hit "Acquire coordinates" the issue arises again and the coordinates are off by double again. Why does ACAD show the correct coordinates but its wrong in Revit after using "Acquire Coordinates"? I've done shared coordinates many times and never have seen this issue.

The image attached is of the plan in Revit showing the line I drew. The blip in the upper right corner is the survey info. The lower left corner is the origin. The numbers shown in the lower left are what it should be reading in the upper right. Instead the upper right is double the numbers shown in the lower left.

[SteveKStafford]

Acquire Coordinates "behaves" if the Remove Location feature is used to eliminate the state plane that is referenced. There is a subtle difference between Feet and US Survey Feet as a base unit but it doesn't seem likely that would double (roughly) the coordinate transposing with AC.

Looks like Specify Coordinates is the "way" forward with this particular file. I don't have the very latest build of Revit 2020 to try it on at the moment. If the DWG is saved in 2013 format that will strip out the geolocation too.

[ToanDN]

I removed the Location from the DWG, removed the line, linked it center to center, acquire coordinates, and the spot coordinates report very closed values.

[barthbradley]

@SteveKStafford: That’s exactly what I discovered. Remove Location and all is right as rain. So, bottom line: this is all about the Geolocation in the DWG.

Not understanding how Specify Coordinates at Point is going is reconcile or mitigate for Revit putting the DWG’s “actual” 0,0,0 Origin at 2325647.533 N/S and 2832021.760 E/W upon Acquiring Coordinates.  

I’m beginning to think that the OP was onto something when he suspected that there may be something wrong with the DWG. Perhaps it wasn’t properly Geolocated.  

[SteveKStafford]

I believe it is the Location defined in Civil 3D/AutoCAD. The Geomarker is located at the origin of the file but it needs to be somewhere near the elements. For example if I place it at the right endpoint of the red line the coordinates work with Location intact. By work, I mean they are much much closer to the actual coordinates of the DWG elements. The geomarker located at the origin seems to double the actual distance to the elements, since (I believe) that's not what the latitude/longitude values really represent in the mapping window. Since I don't know anything about where it really is (lat/long say Indiana) it's hard to "pin" it down...pun intended.

The attached version works "more closely" but the pin location needs to resolved.

[SteveKStafford]

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Not understanding how Specify Coordinates at Point is going is reconcile or mitigate for Revit putting the DWG’s “actual” 0,0,0 Origin at 2325647.533 N/S and 2832021.760 E/W upon Acquiring Coordinates.

Grab the coordinates of one end point in the DWG. Use SPaC at that same location after the file is linked. Now the Shared Coordinate System's origin matches the WCS of the DWG regardless of the "location" defined in it. Just don't use Acquire Coordinates because in 2020+ that defaults to setting location based on geo data if present.

[Anonymous]

Okay, so yes, that did the trick though I am not totally comfortable with it yet. I wonder what turning that setting off may do down the road when tangling with Infraworks and other Civil files from the project. Also curious why Steve and others were able to get it to work correctly on their end without turning off that setting but mine was messed up. Way too many questions here that I'd like to have answered. Maybe I'll bring this one with me to AU next month and let them mull it over.

Thanks for all the help here everyone! Mucho appreciated! And glad to see I'm not crazy. Like I said, I've done these a thousand times and never had an issue like this. I thought I was losing it. I might still be! Cheers!

[loboarch]

Glad you have found the answer.  I was going to take a look at this later this afternoon and perhaps send to the team that works in this area of Revit to look at as well. I will report back anything they find.

[Anonymous]

LoboArch, we found "an" answer. Like I said, I'm not totally comfortable that its "the" answer. Some more notes for your investigation...I am using the most current version of Revit 2019 but also tested this on Revit 2020 with the same result. I was hoping maybe 2019 was just corrupted, but nope. I tried to test it in Revit 2017 but ran into a problem linking the CAD file so gave up on that one. Again, thanks for looking into this.

[ToanDN]

Looks like Revit cannot handle DWG with Geolocation properly just yet.  With that said, I think Remove location is a reasonable workaround at the the moment.  You may wnat to mark @barthbradley  and @SteveKStafford  posts as solutions since we were suggesting the same thing.

[barthbradley · Accepted solution]

Another approach which preserves the Geolocation data in the DWG would be to Reorient Marker to an identifiable location in the DWG, such as a Road Station Point. Save and Link the DWG into a New Revit Project and then move the DWG to place the Station Point (where the Marker was placed) at the Survey Point/Project Base Point Startup Location. Acquire Coordinates. In all of my testing, this produced the more “accurate” end result -- even better than Removing the Geolocation Data. Go figure. Still, there is a great disparity (by several hundred feet) between the DWG and RVT Spot Coordinates with either approach – probably due to the extraordinary extents of the DWG.  Even if you don't Link and Specify DWG Coordinates at one Point in Revit, like a Road Station Point, the other Road Station Point Coordinates don't match up with the Station Point Coordinates in the DWG. 

I'm officially throwing in the towel now.  Bye, bye.  

[SteveKStafford · Accepted solution]

The video in this link describes how it is supposed to work. The key part is the geomarker and survey point need to be in the same location (agreed upon reference point) and then use Specify Coordinates at Point to match coordinates. In this file's case the geomarker is at the WCS origin which is too far from the "project" elements.

When I moved the geomarker to a spot of my choosing at the project elements the Acquire Coordinates process worked.

The workflow Autodesk describes does not use Acquire Coordinates. You manually define coordinates using SPaC and then link the file using By Shared Coordinates. For that to work the geomarker has to be set up well first as well as the file itself. If Revit finds something it doesn't like about the file it forces Center to Center again.

[barthbradley]

@SteveKStafford: What is strange is that I could not get location from survey point until I moved the marker in the DWG.  

[loboarch]

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@SteveKStafford wrote:

The video in this link describes how it is supposed to work. The key part is the geomarker and survey point need to be in the same location (agreed upon reference point) and then use Specify Coordinates at Point to match coordinates. In this file's case the geomarker is at the WCS origin which is too far from the "project" elements.

I was going to point to the same video and that was the method I was going to try.  I will still send this along to development to have a quick look.

[barthbradley]

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@SteveKStafford wrote:

The workflow Autodesk describes does not use Acquire Coordinates. 

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Are you referring to the information you just posted a link to? The way I read it, it implies that you do Acquire Coordinates.  How else would you Link or Get Location From Survey Point?  

[SteveKStafford]

Watch the video. They show using Specify Coordinates at Point (info provided to you or found using Civil 3D) before linking the survey file. Then using link By Shared Coordinates to place the DWG.

The issue with Acquire Coordinates in this thread is that the geomarker isn't marking a location on the property, it's marking the file's WCS origin which is too far from the property. If the marker was place accurately in the survey to mark a boundary corner, like in the video, it could work too.

But the video describes a different workflow, one that depends on the local coordinates system (GIS) provided to us. Those coordinates are not equivalent to the file's own WCS coordinates since the file references a local coordinate system, Civil 3D is essentially doing its own "shared coordinate" system transformation to locate the project "on site".

[SteveKStafford]

Thanks Jeff! I think the issue is the geomarker location is too far from the relevant elements in the file for the Acquire Coordinates tool to do the transformation properly. When I place the geomarker closer the results are much more in line with my expectations.

However the key piece is GIS coordinates (localized values relative to lat/long) versus the file's WCS coordinates (since Civil 3D does its own transformation much like Revit does for SC and PC). For the video's instructions to work the user has to have the GIS values so Revit will recognize the systems can be aligned when linking By Shared Coordinates.

[ToanDN · Accepted solution]

Relocate the Geo marker to a point at the model location is a good suggestion.  I did a test:

- Relocate the geomarker to a point on the curve in the DWG

- Link in Revit center-to-center

- Move the link so that the geomarker matching the Survey Point

- Acquire Coordinates

- PBP reports correct coordinates

- Unpin SP and change the n?S and E/W values to 0 and it will move to the WCS 0,0,0 of the DWG.

[barthbradley]

Ah! I hadn't noticed the Video. Thanks @SteveKStafford. 

Fun thread. Good Discussion. Very informative.

Thanks all.  

[barthbradley]

That video was very helpful. Thanks. 

FWIW: Step-by-step with illustrations:

1. Open the DWG and Reorient Marker to “Sta 3626+8.54” (ID=2832517.2566, 2325421.1037, 0).

2. Save and close the DWG.

3. In RVT Plan View, Unhide Project Base Point, go to Manage =>Coordinates=>Specify Coordinates at Point and then click on the Project Base Point and enter the ID coordinates from Step #1. N/S=2325421.1037, E/W=2832517.2566. Elev.=0.

4. Go to Insert=>Link CAD and Open DWG via “Auto – By Shared Coordinates” Positioning.

5. Click OK in response to “extents greater than 20 miles” message.

6. Click Align in “Link CAD” dialog box.

7. Move the Linked DWG’s “Sta 3626+8.54” to the Project Base Pont. Press OK in response to the Warning that pops up (Recommended). NOTE: If you press Save Now, you will overwrite the existing “REVIT60-DefaultLocation” Named UCS in the DWG (sidebar image).

8. Go to Manage=>Location=>Location. Define Location by: Get Location From Project Base Point and click OK.

RVT’s Project Base Point Location/GIS Coordinates match DWG’s Geographic Marker

9. Verify RVT Spot Coordinates match with DWG IDs.

10. Change Shared Site Name (Recommended). This will create a Named UCS in DWG upon saving position back to the link.

11. Save RVT Project and Shared Site Position/Name to DWG Link

[SteveKStafford]

I mocked up my own test by starting in AutoCAD and creating a fictitious project site in Austin, TX by placing a Geomarker at the corner of a building in the Map view. I was able to get it all to work without using SPaC, I used Acquire Coordinates instead and got the shared coordinates I expected to see. As @ToanDN described, placing the Geomarker in the right place (known) and moving the link so that location and the Survey Point were the same permitted Acquire Coordinates to do its thing.

The OP issue boils down to the Geomarker being at the WCS origin while the project elements were very far from that.