Why set the internal origin so far away from the shared site's origin?

[M1k3y2014]

Hi,

(I'm not working in design myself, more related to supporting technical issues and data, which is why I haven't been able to direct these questions directly at the source)

Why is the internal origin sometimes set so far away from the shared site's origin? I've quite frequently seen Architectural projects where the N/S E/W coordinates read something like (30 000 000, 40 000 000) ~so 30 kms and 40 kms - and in the best cases thousands of miles/kilometers away, meaning that the points are effectively countries away from each other.

For large projects a number of miles is understandable to me, with huge complexes spread out over large distances, but occasionally I've seen these huge distances for fairly small, single buildings.

Why is this done like this? Is there a clear plan (and why exactly), or is there a mistake behind these actions (what can be the reasons for mistakes like that)?

[Avaris.]

The mistake is often due to ignorance.

For example, the template is made without taking this into account. It is however very important to model close to your internal origin. Revit has some issues related to models far from the internal origin.

Within our company, the internal origin is marked by crossing reference planes, so nobody can forget where it is.

[constantin.stroescu]

These layouts comes from a Surveyor file that use an overall integrated system ( that can be different from country to country or areas.....for instance...in my country we use Stereo70). This is very helpful because every location has a unique position in a defined system.

It ' s good to preserve these coordinates in order "to speak the same language" with the other designers that work on the same project with you.

You can change the position of the symbol of the Survey Point , doing this:

• click on the Survey Point symbol and Unclip it
• move the Survey Point Symbol to to a location you want,closer to your object
• then from Manage>Coordinates>Specify Coordinates at Point - write down the surveyor dimensions of that point (North/South and East/West)
• Unclip the Survey Point

[Anonymous]

Hey @constantin.stroescu,

Following your answer, with a question.

I usually have the Shared point/Survey point at a point defined by the surveyor with the data setting the distance between this point and the "Projected coordinate system" of the region, so that the point isn't as fare from the IO.

This usually define the site set up, The IO and PO are very close to the SP(Shared point).

Then share this point to the PO of the Building (To be as close to the IO of the project as possible).

Could you explain a little more about the advantage of the "Overall Integrated System" ?

I guess have never encounters this type of system, as it sound more like a Absolute zero set up. This sound however quite interesting if the overall discipline can take it.

Thank you,

best,

[constantin.stroescu]

maybe it wasn't the most appropriate name for this.....I've tried to find some examples of what I meant .... a Coordinate Reference System used at a National Level ( elipsoid projections as Mercator, Gauss-Krueger, OSGB36 -in UK , UTM zones and State Plane Coordinate System in US , Stereo70-in Romania)

I am not a specialist in Survey ...but it seems that there will be some changes in here.....http://gpsworld.com/surveyors-coordinate-systems-for-2022-and-beyond/

 

[Anonymous]

Thank you for this reference,

Its an interesting topic to be able to uniform those geolocation, it can reduce coordination issues. I was also wondering if this has an impact on the location of the SP relative to the IO/PO as, the survey point of a project will remain the data provided by the surveyor at a specific point of the site.

I am also eager to understand your workflow as it could improve mine.

Best regard,

~GH

[M1k3y2014]

It seems like we are getting closer but I don't perhaps fully understand yet.

So does this mean that there are a number of points set out over the map for example for a country where a number of points are strategically placed on the country's map and then one decides in relation to which of these points the planning is done?

And if it is agreed that point "A" is the one and it is (32 km, 20 km) away from the point where the building is being planned then the coordinates are set up so that they are N/S 32 000 000 and E/W 20 000 000?

[Anonymous]

I maybe confuse but here is my view of it. Surveyor will uses Projected coordinate system such as this: https://epsg.io/3997 to define the SP(shared point) on the site. This point will be uses to define the position of every PO.

This point will most likely be along the property limit. In this case, the point will most likely be closer to the PO/IO specially in small project but this all depend of the size of the site.

In some case, when the project is part of a very large master plan, several site may be related to a single survey point, then the SP(Shared point) will but further away from the PO/IO.

[SteveKStafford]

What Revit does with the Survey Coordinate System origin, when Acquire Coordinates is used on the survey file, is move the Survey Point icon to mark the World Coordinate System origin of the survey file. That is most common reason why it is offset so far.

As mentioned, un-clipping the Survey Point icon will allow it to stay closer to the Project Base Point icon and model. I do that before using Acquire Coordinates. The values displayed in the Survey Point icon indicate how far it is from the Survey Coordinate System origin, if it isn't at the origin.

Also as mentioned already, the coordinate system the survey file is defined by or depends on is determined by where the project is in the world and what the local standards require. Revit's system is a simpler response, it determines where that file's origin is and sets the Survey Coordinate System origin to that same location, based on where the file is located in the Revit model.

Revit wants us to create our model and link external files so it is all very near or centered around it's Project Coordinate System.

[constantin.stroescu · Accepted solution]

I've made a rough video to show how I use a Surveyor CAD file linked to the Revit file so to be able to have a good collaboration with other teams involved in the construction process. I always try to keep unchanged the coordinates from the surveyor file.

As for the National Coordinate Systems and the area they cover, this site can be a guide for:  http://epsg.io/

[M1k3y2014]

@constantin.stroescu

Thank you very much for this video on my behalf as well. I might have to re-watch it and think over it to fully grasp all aspects but I'm really grateful that you took the time to show this workflow. 🙂

[barthbradley]

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@M1k3y2014 wrote:

Why is the internal origin sometimes set so far away from the shared site's origin?

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This is fairly common. It’s all about shared positioning. In fact, your Architectural Project could “remember” is position/orientation relative to several different shared coordinate systems. Open the Site Tab under the Site Location and Weather dialog box (Manage=>Project Location=>Location), and check it out. If there are multiple site names listed, the one that is marked “(current)” is the one that the Project is currently referencing.  You can “Make Current” any one of them. Go ahead and do it. It doesn’t have any effect on the Project. It just repositions the shared site origin in the Project. Additionally – as mentioned – your Architectural Project could have Acquired its coordinates directly from a CAD Survey Map that was (or still is) Linked into the Project. Open your Mange Links dialog box to verify.     

Here’s some more information that may be of help to you:

http://au.autodesk.com/au-online/classes-on-demand/class-catalog/2013/revit-for-architects/ab1412#ch...

http://au.autodesk.com/au-online/classes-on-demand/class-catalog/2013/revit-for-architects/ab1412#ch...

[Radish_G]

Hi @constantin.stroescu ,

Wow, well said.

Sweet and simple.

Appreciated your time & effort.