Attaching an XREF from autocad?

[rob2218]

using AC12.
trying to "External reference" attach a DWG file from Acad.
thing is....it comes in locked which fine I can unlock "ALL" the layers.
but....I can't seem to "MOVE" the linework?
what gives?

whats the appropriate setting I need to attach an XREF drawing in from Autocad??

[Anonymous]

You can't move individual lines in an X-Ref, you have to alter the original file. If you want to move the whole thing make sure Grouping is ON.

[rob2218]

thanks, understood that the acad DWG xref comes in as one big grouped linework of elements.
that I understood.
I also found out that if you put the DWG xref onto a "worksheet" then you can actually "drag" the worksheet around as needed.

thanks.

[Laszlo Nagy]

You can also use the Drawing Tool to place the DXF file.
It is a clean solution, the whole thing is one piece, you can move it around easily, and it does not pollute your file with its own attributes.

[Da3dalus]

I'd like to expand the discussion on this: When importing DWG as-built or background drawings on which to start your model, what are the pros and cons of "Place External Drawing" vs. "Attach Xref"?

I think it's now a common and recommended practice to import these onto a Worksheet, where they can be used as an overlay, correct?

From what I can tell, it seems the main difference is that X-refs bring in layer information, which can be turned on and off (nice if you have ceilings, annotation, etc. in the drawing), while Drawings bypass all of that and show everything, which is generally simpler. You can also crop Drawings, add them to Layouts, and adjust scale, color/pen set, and overall layer. Xrefs have very little control, other than Unloading and changing the file reference.

I wonder which one uses more resources to process, and leads to a bigger file size? I would imagine Xrefs are more intensive.

Can anyone think of other issues? I'm trying to anticipate pitfalls before I reference a whole bunch of plans into a large building model, and wish I did it another way.

[Laszlo Nagy]

Here is a resource that summarizes these things:

http://www.archicadwiki.com/TechNotes/Using%20DWG/DXF%20Files%20in%20ArchiCAD

Regarding the Layer thing: in AC14 you can now individually show/hide the layers of a DWG/DXF brought in as a Drawing.

[Anonymous]

Chuck

For the purposes you mention, I would never use External Drawings. The 2D you get are messy, and you want control over their layer visibility.

If you are dealing with a large amount of 2d floor plans, or if you expect some updating to those, my advice is:
1- Take a empty file and create as many floors as drawings.
2- Xref the drawings into the empty file, one for each floor.
3- Create the same number of extra floors on your main file (hide them in sections and elevations) over you modeling floors.
4- Hotlink the floors from the first file into the modeling file, floor by floor.

There are a number of advantages to this method, namely:
A- As drawings are Hotlinked (and not Xrefed) on your modeling file, you get a master layer to control each drawing visibility.
B- When the file starts to get slow and heavy, you just deactivate the hotlinked floors you are not needing at that point. 2d drawings tend to take resources from your system.
C- Updating external drawings remains very easy, because they are xrefs anyway to the first file.
D- You may want to get inventive and tweak the original drawings (eliminate unwanted layers full of trees and such). You can do this in the first file (the one that has the dwgs xrefed), simply by "Binding" the xref and changing the drawing.

So, in essence, you get all the advantages of the Xref and the hotlink modules.

[Anonymous]

Da3dalus wrote:
I'd like to expand the discussion on this: When importing DWG as-built or background drawings on which to start your model, what are the pros and cons of "Place External Drawing" vs. "Attach Xref"?

I use the Worksheet method and have placed, xRef'd and imported all manner of drawings (DWG, DWF, PDF, etc.) I mostly use placed drawings (even set a hot key for it) as it is the least hassle and works for all file types. The main advantage I find to xRefs is that you can spacebar click (magic wand) the entities in the drawing. With placed drawings it only finds the extents of the drawing.

Layer control is not a big issue to me in either placed or xRef'd drawings since I don't like managing all those AutoCAD layers in ArchiCAD. I prefer to open the file in AutoCAD and adjust the layer states there. This works just as well for placed drawings as for xRefs.

As far as performance goes I have created many worksheet references like this with no noticeable performance hit. On some of my larger projects I'm sure I have well over a hundred such worksheets.

The only drawback that I have found to this method is that the background remains the same when you switch stories in the floor plan view so you also have to switch the reference. With Miguel's method the floor plan overlay will change with each story. This is a trivial issue for me as I am constantly changing references anyway between floor plans, RCPs, structural plans, steel shop drawings, etc so changing references is just part of my accustomed workflow.

[Anonymous]

Matthew wrote:
As far as performance goes I have created many worksheet references like this with no noticeable performance hit. On some of my larger projects I'm sure I have well over a hundred such worksheets.

You have to teach me how you do that Matthew, because my results are totally different.

The more Xrefs I have on a single file, the slower (and bigger) it gets.

I just did a simple experience, with a 1.5mb .pln file. Before attaching anything, it saved in about one second.
After attaching via xref a 1 mb .dwg, it took 5 seconds to save.
After attaching another 1mb .dwg, it took 11 seconds to save.
The last file (1,5mb .pln with two 1mb .dwg attached) now weights 15mb.
If I deactivate saving compression, it baloons to 45 mb without significant performance improvement while saving.

I can only extrapolate, but if I attached a hundred .dwg via xref, with 1mb each (which are not big drawings) it would take me at least 10 minutes to save or open, and would weight some 500mb at least. And that is without the model, views and layouts.

Even if I do some heavy cleaning from the dwgs (which is always risky because you could be trowing away the baby with the water) it still would take many minutes to save and easily reach critical file dimensions.

[Karl Ottenstein]

Forgive me if I missed this in skimming this thread...

But there is also a new feature in ArchiCAD 14 which lets you place external drawings and control the dwg/dxf layers via the new embedded layer feature.

You control layer visibility as shown via the Drawing Tool settings - the dwg/dxf layers never appear in the project Layers. If the source file uses layers in a way that works with what you want to present, this is a way of avoiding the old import/merge/modify workflow.

Cheers,
Karl