Multiple Survey Points

[JSN]

For a matter of facts we need to have multiple Survey Points in a file.

However, afaik for IFC Export only the first (?) placed SP is taken into consideration and defines the IFC Origin. Is there a way to choose (or activate/deactivate) which SP should be used for exporting?

[Minh Nguyen]

Hi,

Thank you for the question!

Yes, it is correct that, if the ARCHICAD project contains multiple Survey Points (though it is recommended to use just one), then the first placed Survey Point will be used. Unfortunately, the program will consider the Survey Point even if it is not visible in the exported view (i.e. if it is on a hidden layer)! The best option I could think of is using hotlink when you want to export the file to IFC.

Thank you very much for your understanding! Let me know if you have any questions!

Best regards,
Minh

[JSN]

Ok, I somehow figured out a workaround.

You are mentioning hotlinks as well, I guess because the SP of hotlinks are always ignored - even if there is no "native" SP in the Host file. Right?

[Minh Nguyen]

Hi,
....
I suggested using hotlink module is because we can completely get rid of the survey points without deleting all of them (hiding survey points of course does not help), and then import them back when we need.

I hope my explanation is clear enough. Please let me know if you have any further questions!

Best regards,
Minh

P/s: edited due to misinformation. Please see the discussion bellow

[JSN]

mnguyen wrote:
Hi,

Unfortunately no. If we place a survey point in the hotlink module, it will still be exported to IFC through the host file. If a survey point exists in the plan, it will be the origin of the IFC model no matter what.

(...)

I hope my explanation is clear enough. Please let me know if you have any further questions!

Well, it is still a bit a mystery ... so I did a test.

Here you can see
- a host file with a SP - (marked in green) and its AC Origin (marked in yellow)
- two IFC linked as Hotlink (and they come with a SP as well) - marked in red

So what I did now was that I exported this file twice ...
- With the SP in the hosfile
- Wihtout the SP in the hostfile

... and I added all of them including an Origin Marker to Solibri. - maked in red below

That's what I got.
- The file with SP is placed with an Offset, as desired - marked in green
- The file without an SP in the hostfile is placed With the AC Origin - the SP of the Hotlinks are getting ignored, though I did not touch them and I have not changed any translator settings. - marked in purple

So, what does this mean?
a) IFC Hotlinks SP are different - but why is there no visual difference
b) I have not understood what you explained and Hotlinks with SP do against all odds do not make any difference
c) It is still black magic anda mystery what's really going on.


BTW: Editing posts with pictures here is just so painful due to the lacking interactive preview and the small text editor window and the missing feature to copy-paste rich content in an instant. Not that I have not mentioned this a few times before.

[Minh Nguyen]

Hi,

Thank you very much for your test!

This is very strange! I was able to reproduce this using a simple column placed at the origin. The result is different in case of hotlink module vs placing Survey Point in plan. I will talk with my colleagues about this issue. I am very sorry for the misinformation, and thank you for letting me know!

Best regards,
Minh

[Minh Nguyen]

Hi again,

Thank you once again for your input! It is true that Survey point is neglected if it is placed in the hotlink module. With this way we can make sure that incoming hotlinks will not modify the position of our model unintentionally.

I am truly sorry for the misleading information, and I can't thank you enough for pointing it out for me!

Best regards,
Minh

[JSN]

mnguyen wrote:

It is true that Survey point is neglected if it is placed in the hotlink module. With this way we can make sure that incoming hotlinks will not modify the position of our model unintentionally.

Thank you for clarifying that. It is good like it is.

Ok Minh, I have another question related to the Survey Point!

I have setup my IFC Import Translator like that: Match AC Project Origin with IFC Global Origin



However, this does sometimes somehow not affect the Z-Coordinate:


(this is the SP from the IFC Hotlink - there is no other SP in the host file)

Question: Why? My Story Height is 0.00 and I could not find any other settings so I always have to manually move it to Z-Zero. Or even better, is there a way match IFC SP with an already placed SP of the host file (which is responsible for the export)?

(This issue is just in AC, in Solibri e.g. the height is correct)

[Minh Nguyen]

Hi,

Thank you for the question!

I tried to look for any written material on what the difference is between IFC Global Origin and IFC Site Location when you hotlink an IFC file, but nothing useful comes up so far.

I'm wondering during hotlinking, is there any Additional Offset set? From my experience, this should affect the Z value in Survey point in hotlink module.

Best regards,
Minh

[JSN]

mnguyen wrote:

I tried to look for any written material on what the difference is between IFC Global Origin and IFC Site Location when you hotlink an IFC file, but nothing useful comes up so far.

I spent already a notable time on researching and experimenting and I could not find that much on it either in the documentation.

mnguyen wrote:

I'm wondering during hotlinking, is there any Additional Offset set? From my experience, this should affect the Z value in Survey point in hotlink module.

No, definitely not. It is set to zero for sure and I tried it out multiple times in and with multiple files. Always the same result.

However I did some further experiments with the file above:

A) I placed it with AC Origin = IFC Site Location


B) I placed it with AC Origin = IFC Global Origin


Ok, so as mentioned before X & Y are changed correctly according to the settings, but somehow Z does not.
While in other IFC Viewers (which of course bring the model always by default up with the IFC Global Origin at their Origin, it is correct - meaning Z = 0


Well, one step back: I could get hands on the original Revit Model and it looks like that there ...

So what you see is, that there is a SP, which becomes the IFC Global Origin and is detected as such one by Solibri and Bimcollab Zoom IFC Viewer. Then there is the slab as our reference point which has a TOP GLOBAL Elevation of -45.5mm. So far so good, let's have a look on it in the IFC Viewers.

In Solibri: It is built up as supposed and the Global Top Elevation of the Slab is matching the -45.50 mm

Nota Bene: the Top/Bottom Elevation (no Global) is given with -50.00mm/-20.00mm so when you add the slab thickness of 150mm here you have a delta of 0.5mm here!

In Zoom: The IFC builds up also correctly and the Global Top Elevation of the Slab is also matching the -45.50 mm

<<< Here should be another screenshot but I could not upload it probably due to an upload limit > so see the next post! >>>

Marked in yellow however, you now get the values we already now from the AC Origin = IFC Site Location hotlink version SP above ... BUT mysteriously the Z Value here is not negativ?

These values by the way might be Internal Origin values from the Revit File.

So, to sum it up:
I am still not sure what is causing this offset when hotlinking in AC but it really looks like that in the match IFC Global Origin with AC Origin setting the Z value is not taken from the global values but from the IFC Site Location values. I am aware that the Revit IFC Export is quite shitty but in this scenario we see that native IFC Viewer get the position right here so it's probably not all Revit to blame here?