topic Re: Way to localize coordinates without cad survey data? in Revit Architecture Forum

Way to localize coordinates without cad survey data?

Sunman75 — Wed, 22 Jan 2025 09:06:56 GMT

I would like to locate and annotate property corner posts of a project according real world geolocation coordinates (ETRS-GK27FIN in this case).

Survey point coordinates can be assigned according this, but the rest of (spot )coordinates will obviously not match the local coordinates, since Revit is using some other coordinate system by default?

Is there a way to tell Revit which local coordinate system to use -other than with auto cad survey file?

Re: Way to localize coordinates without cad survey data?

jay_colc — Wed, 22 Jan 2025 09:14:33 GMT

Within the Spot Coordinate Family, you have the option to choose the Coordinate base. you can duplicate an existing Type and change it to your requirements

Annotate Tab > Dimensions Panel > Spot Coordinate > Propeties Palette > Edit Type

Re: Way to localize coordinates without cad survey data?

Sunman75 — Wed, 22 Jan 2025 09:22:41 GMT

This is not the issue. Spot coordinates are based on survey point.

Re: Way to localize coordinates without cad survey data?

Sunman75 — Wed, 22 Jan 2025 09:32:51 GMT

Re: Way to localize coordinates without cad survey data?

jay_colc — Wed, 22 Jan 2025 10:17:05 GMT

I have probably misunderstood the question, just to clarify have you tried creating a Spot Coordinate for Site/Project/Local and clicking on a single point?

Re: Way to localize coordinates without cad survey data?

RDAOU — Wed, 22 Jan 2025 20:03:05 GMT

@Sunman75

If the geolocation and coordinates are defined in a CAD file linked to Revit, you can use Acquire Coordinates to establish a shared coordinate system between your model, the survey data, and all future linked models to be used in the project (Structural, Mechanical, etc.).

Alternatively, you can use "Specify Coordinates at Point" which will relocate the drafting plate (the Project as a whole including the Internal Origin) to that specific point. Subsequently the other spot coordinates will readjust accordingly

Note: After relocating project

Uncrop view
UNCLIP Suervey Point
Drag to the relative point on the site boundary
RECLIP the Survey point

Re: Way to localize coordinates without cad survey data?

Sunman75 — Wed, 22 Jan 2025 11:32:31 GMT

Thanks for commenting, maybe my question is not clear...

No CAD file available - thus survey point here is assigned by specify coordinates at point. Coordinates taken from map where local coordinate system (Datum ETRS-GK27FIN in this case) selected.

I would like to see spot coordinates (based on survey point) match the same coordinates on same spots on a map.

As you see, spot coordinates Revit is giving are way off now.

Hence the question, if this is doable without CAD based survey at all?

Re: Way to localize coordinates without cad survey data?

Sunman75 — Wed, 22 Jan 2025 11:47:30 GMT

This probably is the answer:

Issue: What is the default GIS/EPSG coordinate system in Revit model without linking a DWG file or importing a coordinate system from an external file

Causes:The default Revit model/project has an X, Y and Z axis of cartesian coordinate system where the Internal Origin, Project Base Point and Survey Point are defined in 0,0,0 coordinates defined in project units (meters, milimiters etc.) .

Solution:The default Revit model/project does not have a definition of default GIS/EPSG coordinate system.

Note: This information can be obtained from the linked georeferenced DWG file only.

From here:

Re: Way to localize coordinates without cad survey data?

azad.Nanva — Wed, 22 Jan 2025 12:31:15 GMT

In Revit, setting up and managing real-world geolocation coordinates can be challenging, especially when working with systems like ETRS-GK27FIN. Revit uses its internal coordinate system by default, which may not align with real-world systems. However, you can configure Revit to work with a specific coordinate system like ETRS-GK27FIN.

You can manually align the coordinate system using a known point or set of points:

Choose a known property corner or geolocation marker with exact ETRS-GK27FIN coordinates.
Adjust the Survey Point and/or Project Base Point to match the real-world location.

Revit itself does not directly support working in multiple coordinate systems or transforming local spot coordinates into specific real-world systems. You can, however:

Use a third-party plugin (like Dynamo scripts or other add-ins).
Transform coordinates outside of Revit (e.g., export points to a GIS or CAD tool, apply the transformation, and re-import them).

Some add-ins support more sophisticated geolocation workflows:

Tools like Autodesk Geolocation for Civil 3D/Revit Integration can help.
Plugins such as FME or Autodesk InfraWorks may support advanced geospatial transformations.

Re: Way to localize coordinates without cad survey data?

RDAOU — Wed, 22 Jan 2025 20:07:29 GMT

@Sunman75 wrote:
This probably is the answer:
Issue: What is the default GIS/EPSG coordinate system in Revit model without linking a DWG file or importing a coordinate system from an external file
Solution:The default Revit model/project does not have a definition of default GIS/EPSG coordinate system.
Note: This information can be obtained from the linked georeferenced DWG file only.

From here:

@Sunman75

That article is covering part of what I stated in my previous reply. As stated

Method ONE: if you have a CAD file where the geolocation and coordinates are defined, you can use aquire
Method TWO: if you do not have a CAD file you still can input the values manually and relocate the survay point given that you have the values
1. You use set points at coordinates to set out your project and your benchmark/survey point
2. Then you enter the distance/bearing of the property line manually.

Using method two above will give you the same readings which you have shown onn the image.

Setting out the survey point while unclipped would give you absolute readings with respect to the origin of the cartisian system. Whoever would receive the revit model from you, would ultimately NOT USE IT before they establish a SHARED COORDINATE SYSTEM.

The one usefull thing which Revit does not offer you, is placing elements at coordinates.

Re: Way to localize coordinates without cad survey data?

RDAOU — Wed, 22 Jan 2025 13:31:11 GMT

@Sunman75

if you can provide the highlighted coordinates I can show you how you would do that in revit

Re: Way to localize coordinates without cad survey data?

Sunman75 — Wed, 22 Jan 2025 13:52:55 GMT

Thanks, Here you are

Re: Way to localize coordinates without cad survey data?

SteveKStafford — Wed, 22 Jan 2025 20:24:52 GMT

I wrote a blog post describing how I used Dynamo to place "points" at specific coordinate locations, it might be useful?

Re: Way to localize coordinates without cad survey data?

RDAOU — Wed, 22 Jan 2025 20:59:30 GMT

@Sunman75

Attached is a 2022 version of the Revit File with the property lines based on the points you gave @ ETRS-GK27. There are three points missing so I made a rough assumption. If you provide the missing points I can re-edit this

Re: Way to localize coordinates without cad survey data?

Sunman75 — Thu, 23 Jan 2025 06:45:07 GMT

Thank you for the effort. I'll add missing/needed points my self as soon as I study and understand what the process is.

Re: Way to localize coordinates without cad survey data?

Sunman75 — Fri, 24 Jan 2025 13:03:55 GMT

I am a massive idiot. I'm ashamed to admit that greatest issue here was that the Spot coordinate label was set to default units=project units=mm, which caused spot coordinates to go way off.

If I had this set to correct units from the beginning, I would not have posted the question and probably just been happy with few meter accuracy you get when picking the property lines from internet mapping services.

NOW however, thanks to @RDAOU, I have my property lines and their coordinates exactly spot-on! Without CAD survey data.