topic Project origin, User Origin & Survey point in Modeling

Project origin, User Origin & Survey point

LFBIMMAN — Tue, 13 Jun 2023 00:03:25 GMT

Hi All, I am getting a bit confused with the co-ordinate system in Archicad

Could anyone please explain the difference between Project origin & user origin for me please & why I can move the user origin & an example of why I would possibly need to move it please? I have already read the graphisoft help pages but didn't really understand.

they both seem to read 0,0 even though they are away from each other.

Alot of our projects have no requirement for real world co-ordinates so our process for generic projects is to start modelling as close to 0,0 as possible, most of the time the corner of our building is placed directly on 0,0. The project origin & user origin is placed on the same spot from default, we don't really move these.

Another thing I don't really understand is the difference between these 2 co-ordinate objects..... any clarification would be welcomed.

Re: Project origin, User Origin & Survey point

Barry Kelly — Wed, 07 Jun 2023 11:30:44 GMT

The Project Origin is the true origin and it can not move.

It will always be 0,0,0.

It really does not mean a lot, it is just that every model must have a Project Origin.

The User Origin can be moved and is simply for your convenience to to set any point you wish as the origin 0,0,0.

As you mentioned you always place the corner of your building on the Project Origin (excellent - always model close to the Project Origin).

You can set the User Origin to a different corner of the building or maybe the corner of a room, so you can get distances from that point.

As you place elements, a temporary User Origin is placed at the starting point of that element and then you can specify the length of a wall or slab or beam, etc.

A survey point just allows you to set a World Coordinate at a given point.

This saves you having to model very far from the Project Origin if you are trying to use real world coordinates.

Modelling far from the Project Origin will cause problems due to the large numbers for the co-ordinates.

So you set a Survey Point close to the model (or even on the Project Origin) and give it the real world co-ordinate of that position.

Positions on your building can then be related to that survey point giving you real world co-ordinates for the building.

Barry.

Re: Project origin, User Origin & Survey point

Nicholas Jones — Wed, 08 May 2024 16:34:52 GMT

Barry,

id be grateful for your input on the below

I have been having a bit of a head scratcher with this,

I'm understanding that the survey point will always relate to the project origin for setting up real world coordinates

I'm having an issue now where I have a file where the project origin is randomly located, Id like to place the survey point on one of the surveyor control points (where I know the coordinates) and specify that this area is x real world coordinate without worrying about the project origin.

but this seems impossible? The only thing I can think of is to move the entire project so that the origin is aligned to a grid reference, which of course messes up all views and layouts.

Am I missing something here ?

im on V27 now and I understand there has been some changes.

Re: Project origin, User Origin & Survey point

Barry Kelly — Thu, 09 May 2024 05:33:11 GMT

I am not sure I will be a lot of help as I don't use the survey point.

The Project Origin can not be at some random location as it is always 0,0,0.

The model can be placed anywhere in relation to the project origin, but it is always best to keep the model as close as possible.

You can place the Survey Point at any distance in relation to the project origin - that is the easting and northing values - simply the X and Y distance you want your model to be from the surveyors control point.

You then set the longitude and latitude in the survey point for your known location.

The project origin will now effectively become that longitude and latitude.

So now any part of your model that is at the project origin will effectively be at your known surveyor's control point.

You can see here I set the survey point to 0 longitude and 0 latitude.

Any co-ordinate that I check will be measured from the project origin, but will show the co-ordinates in relation to the survey point long/lat settings.

Barry.

Re: Project origin, User Origin & Survey point

Barry Kelly — Thu, 09 May 2024 05:43:52 GMT

Although I do notice a slight error when crossing the 0 long/lat lines.

Shouldn't be an issue when yo set the correct long/lat.

Barry.

Re: Project origin, User Origin & Survey point

Lee Hankins — Thu, 09 May 2024 06:24:33 GMT

Ideally you need to place your data so that the Project Zero bold ‘X’ sits on an intersection point of the surveyors grid as close to your model data as possible or another known coordinate. Now depending on how you plan to use the data from the surveyor you may need to rotate the north point. If you keep the surveyors data at the rotation it was originally drawn at then north will remain pointing up the screen. If you rotate the survey data so that you are drawing your model data in x,y coordinates then you will need to rotate the north of the survey point to match the north of the rotated survey data.

Once you have the north set up correctly you then need to relocate the survey point to the coordinates of the point you have placed it on remember it needs offsetting negatively so if your grid point or known reference point is 100 north and 100 east you’d have to input those coordinates in to the pop up tracker of the survey point as N:-100 and E:-100.

Once the survey point is relocated I then always place a coordinate dimension object on the known reference point to check its correct and then place a text box next to it with the same coordinates manually typed in. This way of the survey point gets moved by accident you can see when there is a discrepancy between the object and the manual text.

I hope that makes sense.

The guide is quite useful.

https://help.graphisoft.com/AC/27/INT/_AC27_Help/020_Configuration/020_Configuration-35.htm

Re: Project origin, User Origin & Survey point

Nicholas Jones — Thu, 09 May 2024 06:53:41 GMT

Thanks both

yes this confirms what I understood

this file was set up before surveyor data came in so the origin is not aligned with the grid although I probably could work it out and adjust the survey point as you say.

It'd be nice to have a way to retrospectively align project 0,0 or have another point represent that for the survey point data without having to move the entire model.

Re: Project origin, User Origin & Survey point

Lee Hankins — Thu, 09 May 2024 15:24:24 GMT

You don't need to move the model. that's the point of the survey point. If your project zero isn't located on a known co-ordinate from the survey data, just work out where it is relevant to the nearest grid or known point and then move the survey point by those dimensions.

Re: Project origin, User Origin & Survey point

Nicholas Jones — Thu, 09 May 2024 15:49:10 GMT

Thanks for the reply Lee,

I think I understand even though I ended up moving the model anyway.

If I come across this again, I'd work out the origin coordinates based on the grid then subtract those numbers (with the survey point at 0,0) in the survey point settings in location settings and I should get the same result.

Re: Project origin, User Origin & Survey point

Joel M — Mon, 09 Dec 2024 12:39:12 GMT

I was trying the use the "new" survey point but it seems it dosent work in the same as before. Before i could set the surveypoint in AC 0,0,0 and "say" it was the coordinates 100,000,000 and 100,000,000 in real world, so when i exported IFC my origin in AC would the the real worl coordinate. Now it seems the survey point only allows to change the origil (null point) to another place. Or im missing something here?

Re: Project origin, User Origin & Survey point

scottjm — Mon, 09 Dec 2024 22:04:16 GMT

An important concept to understand with the survey point is that its locations in Archicad translates to Easting:0 and Northing: 0 NOT the actual Easting and Northings of a known surveyors benchmark of your site.
ie the position of your Survey Point is the 0,0 origin of the real world co-ordinate system.

So an example:

You have a building modelled and the SW corner of the building is at 0,0 Project Origin and 0,0 User Origin.

Then have a known surveyors benchmark 20m to the west of that corner of the building and its Eastings and northings are:

E: 334,886.431m

N: 6,252,283.616m

(MGA2020 Grid 65 - Australian Grid System, location is in Sydney).

So what you need to do is take your survey point and temporarily move it over the known surveyors benchmark.
Then you need to select it to move and move it exactly X: -334,886.431m and Y: -6,252,283.616m relative to the known survey benchmark. Note those are negative numbers and the survey point will now be sitting over 6,000km South west of your modelled building.
In the Australia mapping system your survey point is now essentially sitting on the South Pole for ease of comprehension ( it’s not exactly that cause of the crazy maths that projection systems use, but this helped me get my head around it).

So if you place a World Co-ordinates object at your survey benchmark it should the correct eastings and nothings.

E: 334,886.431m

N: 6,252,283.616m

if you place another point at your project origin it will be slightly different, but that’s all ok, cause that is reporting the correct eastings and northings of that point on the site.

Also if you go in the survey point panel the two numbers you see will be negative, but will NOT just be negative versions of your benchmark E/N. That’s because the position of your survey point is relative the the Project Origin, so this discrepancy takes in to account that fact that your survey benchmark is not sitting exactly on the Project Origin.

my recommendation when you know you need to work with real world coordinates is to align your survey benchmark at the project origin to simply your survey point setup. That is if the survey benchmark is not tooo far from your model. I’d suggest no more than 100-200m.

also, when trying to get your head around eastings and northings, forget about longitude and latitude. They are very different things and should not be confused. It’s still worth setting Lat/Long correctly for sun studies etc, but I know in Australia I have never seen a survey benchmark co-ordinates detailed in Lat/Long, only every Eastings and Northings.

Re: Project origin, User Origin & Survey point

Aaron Bourgoin — Mon, 09 Dec 2024 22:36:13 GMT

this is great information. It doesn't ease the pain derived from the limitations of the survey point, but it's good information.

Re: Project origin, User Origin & Survey point

Joel M — Tue, 10 Dec 2024 07:16:43 GMT

Thanks for you reply. I understand the concept, however here in Norway, the AC zero point is always hundreds of km away from the survey location (real world coordinates). The way survey point worked before was perfect, now is just a pain in the ass with extra steps leading to more chances of making mistakes on the way. Very frustrating.

Re: Project origin, User Origin & Survey point

Barry Kelly — Tue, 10 Dec 2024 07:47:01 GMT

Not that I ever have the need to use the survey point, but I really don't think it can get much simpler.

Just type in two figures for Northing and Easting, which is just the distance in what ever units you are using.

You have the Archicad Project Origin, and you should always model on or close to that point.

This Project Origin will be your local site datum.

Your real world survey datum can be a great distance away.

Determine the Northing and Easting distance that your site datum is away from the real world datum.

Add these figures to the Survey Point by dragging it and typing the figures into the tracker or by opening the location settings and typing the figures in there.

If the real world survey point is to the left or below the local survey point, then add negative to the figures, so the real world survey point moves in that direction.

In other words, it is the opposite distance that your local origin is from the real world survey point (global 0,0 if you like).

You are not moving the model, you are moving the survey point in the opposite direction.

Barry