Exporting to Autocad in the Metric world

[luigi]

I searched and searched but can't find anybody posting a problem/question...

Is there a way to export a drawing which the units are cm and have it export to AutoCAD in cm? when exported it is exported in mm. That would mean that every dwg drawing would need to be scaled 1/10 and then if required, the viewport scale of each drawing would need to be scaled as well.

But mainly is there a workaround to export a drawing to the correct unit in AutoCAD using metric scale?:screwy:

[kiadimarco]

I searched and searched but can't find anybody posting a problem/question...

Is there a way to export a drawing which the units are cm and have it export to AutoCAD in cm? when exported it is exported in mm. That would mean that every dwg drawing would need to be scaled 1/10 and then if required, the viewport scale of each drawing would need to be scaled as well.

But mainly is there a workaround to export a drawing to the correct unit in AutoCAD using metric scale?:screwy:
When you are exporting, what is your units set on?

[ivsim]

I've set my project units to "cm", which is what I normally work with, and the dwg's that I 've had exported are in "mm". I've noticed that all the Metric content is set to "mm" (family templates and families) and no matter whether you work in cm environment the DWG's are invariably in "mm"...no idea if there's any connection....

[amara]

This is a known problem with dwg export. Units are exported in mm no matter what you do in revit, and you end up scaling the drawings. Choices are limited. When importing you can specify the import unit, but for no obvious reason you don't have the choice when exporting. As sheets are exported using paper space in acad, scaling drawings means adjusting sheets in paper space. linetypes, dimensions, text etc. all get messed up - a real headache, especially when you have 50+ sheets to do.
Another issue with exporting is xref. sheets are exported in different acad files with xref. This becomes confusing especially many sheets being exported and when you need to edit the acad files, and you end up binding files into one. Shouldn't there be the option to export sheets into one file to the correct unit???? doesn't seem like much but for some reason this has been ignored for so long. I hope somebody at autodesk is listening.

[MikeJarosz]

I've set my project units to "cm", which is what I normally work with, and the dwg's that I 've had exported are in "mm". I've noticed that all the Metric content is set to "mm" (family templates and families) and no matter whether you work in cm environment the DWG's are invariably in "mm"...no idea if there's any connection....

I have found over the years that how Acad handles units confuses many people, especially those unfamiliar with Imperial units of measurement.

Acad cannot convert between units of measurement. But, if you always work in one system of measurements you may never realize this.

If you are a US engineer and need to use decimals of a foot, you are out of luck, because Acad doesn't offer decimals of a foot as an option. The standard workaround is to work in inches and read the dimensions as if they were in feet! This means that the resultant drawing is 1/12th full size. We receive drawings from our engineers like this all the time.

Likewise, to work in what you think is metric, you set units to decimal and draw according to your metric dimensions. For example a standard metric door is 900mm in width. If you were to then set architectural units (feet and inches) you would discover that that door is actually 75 feet wide! (900/12). Or, if you try to import an imperial block into metric, it is gigantic. If you look closely, you will discover the metric image is 1/25.4 of the imperial image. 25.4 -- sound familiar?

The rule, it seems to me, ought to be that an object should not change size because of the units of measurement. I am the same height in metric or imperial. This is the approach that Revit takes. Whatever unit of measurement you set, Revit just converts the annotation for you. In acad, you have to actually scale your data up and down to move between systems. Because 1/12 = .08333333333333+ (an irrational number) this also introduces a scaling error that can sometimes mess up a large area such as a site plan.

Most of the metric projects I have worked on have used millimeters as the base, but I did a job in Brazil once where they wanted everything in decimals of a meter. You just have to scale the data up or down by 1000.

Makes perfect sense, doesn't it?



.

[Scott D Davis]

So it's really an AutoCAD problem. Revit is correct in converting an inch to mm without any scaling. (because an inch = .0254m = 2.54cm = 2540mm) AutoCAD says an inch must be scaled up 25.4 times.

[Henry D]

My work involves a lot of flipping back and forth between imperial and metric.
You don't have to scale down the drawing in Autocad to get to centimeters.
Under the"Desktop" menu go to Drawing Setup and change the units of the exported drawing from Millimeters to Centimeters, it will automatically change the drawing to Centimeters. I have ADT and I am not sure if this feature is available in plain vanilla Autocad.

BTW, I also would very much like to have the option of having the files of the exported Revit drawing all bound into one file, not a bunch of individual xrefed files. Maybe I'll add this to this wishlist.

[FK]

1/12 = .08333333333333+ (an irrational number)
A rational number with infinite decimal expansion. Actually, it's the binary expansion that matters (unless you are trying to type it in), but it's also infinite in this case. To be fair, 1/10 also has an infinite binary expansion.

Didn't you miss your stickler? ;-)

[Nic M.]

(because an inch = .0254m = 2.54cm = 2540mm).

Those are large mm Scott. (I knew everything was big in the States)

I was told that for CAD architectural drawings mm is the unit standard. So we deliver in mm.

[ivsim]

The structural engineer who does steel wants to have their underlay plans in mm, the landscape architect in meters,....if Ihave my dwg in mm and have it scaled in ADT, all of the annotations go to hell i.e. the physical dimensions of the lines and the physical distances among them decrease in comparison to the size of the annotations....what I mean here is pretty simple, it all boils down to units, no matter mm, m, inches and the correlation between them...let's say my door is 90 'apples' wide and 200 'apples' high, the only thing the software needs to do is just say 1 apple equals 10 mm or 1apple equals 1 cm....It might be a very good idea if Revit could handle this unit conversion matter likewise...just wishing....actually I can not get rid of my 'cm' habits. By the way there's a .DWG export translator in ArchiCAD that allows to have the resulted ACAD drawing in whatever units you want.....

IMPORTANT NOTICE!....the last sentence of this article is not intented to promote the qualities of another software or to diminish the qualities of Revit or to become the focus of vehement discussions but to state an actual fact only for the sake of mere comparison and the author does not hold any responsibility as to how the other dedicated users of this site would review the above statement.....:)

I read the ArchiCAD thread and see many people around here are touchy about GS matter....

[Scott D Davis]

Those are large mm Scott. (I knew everything was big in the States
oops, did i screw that up?/ shows how much i work in metric......

Ok, from my 10th grade science teacher: Kooky Hairy Dogs Bite Decent Citizen's Mothers

Kilo, Hecto, Deco, Base, Deci Centi, Milli

.0254 meter = 2.54cm = 25.4mm

Is that right??

[Steve_Stafford]

It might be a very good idea if Revit could handle this unit conversion matter likewise...just wishing....actually I can not get rid of my 'cm' habits.Revit handles units properly, Acad does not. Rather, the people using Acad bend 'reality' by deciding what unit they are 'playing' with. I thought Mike explained it well...

[LRaiz]

The structural engineer who does steel wants to have their underlay plans in mm, the landscape architect in meters,....if Ihave my dwg in mm and have it scaled in ADT, all of the annotations go to hell i.e. the physical dimensions of the lines and the physical distances among them decrease in comparison to the size of the annotations....what I mean here is pretty simple, it all boils down to units, no matter mm, m, inches and the correlation between them...let's say my door is 90 'apples' wide and 200 'apples' high, the only thing the software needs to do is just say 1 apple equals 10 mm or 1apple equals 1 cm....It might be a very good idea if Revit could handle this unit conversion matter likewise...just wishing....actually I can not get rid of my 'cm' habits. By the way there's a .DWG export translator in ArchiCAD that allows to have the resulted ACAD drawing in whatever units you want.....
....
Henry D posted a recipe on how to deal with this situation earlier in this thread. Doesn't it work?

The quoted complain seems to be related to pure Autocad. If Architect created his dwg in cm using nothing but Autocad and his structural guy wants mm while his civil consultant wants meters would not it be reasonable to expect Autocad itself to provide a native solution? Do you really think that it would be productive to have Revit developers spend their time developing tools and workarounds for various Autocad work-flows rather then focusing on plugging remaining functionality holes in Revit?

[tarch]

It is a mater of a simple lisp routine which would convert current measuring system to another. Auto-Architect (Softdesk's predecessor) had it 15 years ago. No scaling, just click on the screen menu.
Alek

[kwong]

Luigi,
Try this - in Revit set your units to mm first to draw, then change your settings to cm before exporting to AutoCAD.

[luigi]

I have found ... Makes perfect sense, doesn't it?.
All does make sense, I was just wondering if there is a way to export to a specific measurement from Revit to Autocad. The problem is that there would have to be quite a lot of time spent to scale each drawing in Autocad, especially if someone wants the sheet layout to be correct as well.

I think that if there is an export from Revit to Autocad, and there is, there should be some additional options, i.e. exporting Revit drawings to actual project unit setting. Maybe it is difficult to scale the export by .1 and modify the model viewport accordingly, especially since scaling is a very new practice for Revit. That would be a different issue than, oh, nobody really complaint so this option wasn't looked at as a feature for the program.

I would be simply happy if the factory knows about this issue, because it is an issue if consultants are used to work in cm only, and not find out that they were just not aware how important it might be.

[tarch]

Physical size of drawn object in Autocad shall always stay the same regardless of measurement unit. If I remember correctly, Autocad's default unit is inch. All needed is applying appropriate scale factor to dimension variable(s). That shouldn't take more than few seconds per drawing. That way you shouldn't have to re-scale titleblocks, viewports, etc.

[MikeJarosz]

A rational number with infinite decimal expansion. Actually, it's the binary expansion that matters (unless you are trying to type it in), but it's also infinite in this case. To be fair, 1/10 also has an infinite binary expansion.

Didn't you miss your stickler? ;-)



You're correct. I didn't want to confuse people. BTW, 1/2 is irrational in binary. Is that what you meant by 1/10, which is the binary for 1/2?

[FK]

You're correct. I didn't want to confuse people. BTW, 1/2 is irrational in binary. Is that what you meant by 1/10, which is the binary for 1/2?
If you insist on calling numbers with infinite expansions "irrational", I'll call your diagrid "rhomboid windows". ;-)

0.5 decimal = 1/2 decimal = 1/10 binary = 0.1 binary, finite expansion
0.1 decimal = 1/10 decimal = 1/1010 binary = 0.000110011... binary, infinite expansion

All of them rational, of course. Generally, since 2 divides 10, every finite binary expansion produces a finite decimal expansion.

[ivsim]

Below is a series of pictures that illustrate, I hope, what it is all about.....

The drawing setup menu in ADT does get the drawing rescaled, perhaps there is a workaround to
set the annotation size right after that.....BUT what would happen if my project comprised
100 drawings that need to be forwarded to an MEP engineer, it would be very confusing, at least
in my view, to have that number of drawings scaled file after file.....

tarch, you are right, BUT if I am supposed to draw something additional I should always be aware
that my units are not what it is written at the dim lines......

There is a workaround, though, that I suppose, the "metric" Revit users might consider helpful.

1 step: Set up a DWG in the desired unit (let's say metric, centimeters) and xref the revit exported dwg;

2 step: On the attach xref menue enter the scale factor that reflects your desired units (in my case
it would be 0.1 i.e. 10 times less); the distances measure as desired and the dimension lines and texts do
not get enormous.

3 step (optional): It is possible to bind the xref to become part of the drawing..

I just wish the Revit team pays some attention to that and what's more, i'd even dream that selected views in Revit
get autimatically exported in the desired units without the user having to click File>Export DWG every time....

Leonid, I am really surprised by you looking down at this problem, there is no doubt,
that the Revit developers have to take their time and focus on "plugging remaining
functionality holes in Revit" but with the above suggestion, I think, you'd free the metric Revit users
from the routine clicks and give them the chance to communicate their current changes in the design to the
respective consultants in an effiortless and less time-consuming way......so I wish you all the best, and I'll be looking forward to
the moment when "all the holes are plugged" and you have the time to figure that out....

[Scott D Davis]

hmmm....if Revit's developers were targeted with fixing all of AutoCAD's problems, we wouldn't see much new in Revit for some time. :shock:

[Henry D]

Ivsim, yes what you describe is a pain in the neck. I now remember when I was using ADT (it seems like eons ago) and used the drawing setup to keep flipping between imperial and metric, what I would have to do is have two separate dimension styles with different sizes to fit the scale change. Since my work constantly involves switching units, Autocad's inadequate way of doing this was a big reason why I dumped ADT and switched to Revit. Revit is great for the kind of work I do.

Autocad is very clumsy with unit conversion even when working only in Autocad, so this is an Autocad inadequacy . I think Autodesk should look at ways of making the .rvt to .dwg conversion better from the Autocad side. For instance, in ADT under the insert menu there would be a Revit import selection where there would be options for scale, inserting files with their xrefs bound, exploded, etc, This would be fairly easy to do with lisp.

In the meantime, in the Tips and Tricks forum I think that it would be useful to pool our collective tips on exporting Revit files to Autocad, I can think already of three tips that I will post there.

[Exar Kun]

hmmm....if Revit's developers were targeted with fixing all of AutoCAD's problems, we wouldn't see much new in Revit for some time. :shock:

True, but doesn't the third image in ivsim's post indicate Revit is doing something wrong here? Shouldn't that wall be 12 units thick in AutoCAD if it was drawn thus in Revit?

[Scott D Davis]

The base units in AutoCAD are mm, so it reads 120 units.

[luigi]

WOW!!!!! :shock:

This thread has took a spin!

There is an issue with the metric world, not the imperial world. The issue is that some people work in cm and others in mm, and I guess I learned that some use meters. The export to Autocad has been enhanced a little bit (I think at least) every new release of Revit. If exporting from Revit to Autocad to the Revit Project Units is difficult (or impossible???? for those in the factory that might feel challenged, prove us wrong ;) ) than that should be the end of it.

But the bottom line, no matter which is the program that is the problem (and we know it is Autocad), there is a problem between the export to an AutoCAD file (dwg) to a specified unit in Autocad from Revit.

It is Revit that has an export to Autocad from the very beginning of its life (at least since 3.0 when I first played with Revit)

So, Revit Technologies found it very important from the beginning.


I am beginning to be sorry for starting this thread:Oops:

[athanasiosmavrides]

I am sorry I am bringing up an old issue, but also in version 8.1 there is no solution to fix that problem. I draw in Revit using meters, with 2 decimal, and when exporting to ACAD it comes to thousands units(5.00 meters in Revit becomes 5000units in Autocad no matter what unit you choose for your acad scale. therefore it comes 1000 times greater than the desired model).

Has anybody found anything out there??
How can this be fixed?

[luigi]

I am sorry I am bringing up an old issue, but also in version 8.1 there is no solution to fix that problem. I draw in Revit using meters, with 2 decimal, and when exporting to ACAD it comes to thousands units(5.00 meters in Revit becomes 5000units in Autocad no matter what unit you choose for your acad scale. therefore it comes 1000 times greater than the desired model).

Has anybody found anything out there??
How can this be fixed?
There is no easy way to do it...unless somebody knows lisp routines....it needs to be converted in autocad, not revit. Revit will export to the main unit, and for Autocad it is mm.
When you insert an acad file into revit, then revit will convert the file to the proper unit, but won't do it if you export it to autocad....autocad should have a way to convert the file to the proper unit....

Peace,
luigi

[athanasiosmavrides]

So, Luigi
complaints about this issue should be directed to Revit support or ACAD support?
What did you do to overcome this issue? Scaling (and destroy everything which is worst than doing it all the way from the beginning)?
Have you reported this issue when you had that problem?

Thanks Luigi anyway!

[blads]

We were discussing this at a recent LUG meeting. In autocad, type in INSUNITS=0 or better still in the ACAD2006DOC.LSP file insert (setvar "insunits" 0).

this way when you insert / export file across, units are ignored.

[Danny Polkinhorn]

We were discussing this at a recent LUG meeting. In autocad, type in INSUNITS=0 or better still in the ACAD2006DOC.LSP file insert (setvar "insunits" 0).
Careful there. You're better off setting it in each drawing. Setting it in the Acad2006doc.lsp file may cause issues with all your other drawings (assuming you're using AutoCAD for other things).

A better way is to manage what Revit is giving you. If the exported drawing is in mm, reference it and scale the xref by 1/1000 to get meters (as ivsim says earlier). This should be old hat for you metric users.

[blads]

Careful there. You're better off setting it in each drawing. Setting it in the Acad2006doc.lsp file may cause issues with all your other drawings (assuming you're using AutoCAD for other things).

A better way is to manage what Revit is giving you. If the exported drawing is in mm, reference it and scale the xref by 1/1000 to get meters (as ivsim says earlier). This should be old hat for you metric users.
This was suggested by a adesk rep as it will not affect existing blocks that may already in the drawing file.

[Danny Polkinhorn]

Blads,

Correct, I was merely mentioning that you might not want to make a blanket change like that just for Revit. If you rely on unit-scaling in AutoCAD, it's probably something you don't want to disable for all future insertions.

My 2¢,

[blads]

Blads,

Correct, I was merely mentioning that you might not want to make a blanket change like that just for Revit. If you rely on unit-scaling in AutoCAD, it's probably something you don't want to disable for all future insertions.

My 2¢,
Quite right, I misunderstood your comments... although its curious why a autodesk rep would mention it all...

as you said, it is far better to control from the Revit end...

[luigi]

So, Luigi
complaints about this issue should be directed to Revit support or ACAD support?
What did you do to overcome this issue? Scaling (and destroy everything which is worst than doing it all the way from the beginning)?
Have you reported this issue when you had that problem?

Thanks Luigi anyway!
Hello,
I haven't overcome anything....
I just either convert the drawings myself (but don't deal with paperspace, meaning exporting each drawing seperately, not from the titleblock), or
I just send the drawings as is to the consultant and tell them that it is in mm (which I have only done once or twice, and definately not to the average consultant)

Usually, consultants need background drawings, not sheets with various drawings, so I give them the background to work on.....Now you can export to a single file, so you won't get multiple files being placed in a single file...

So, sorry, no trick up my sleeve....(I would have shared such a trick)

Also, I didn't report it to any official source... :( I just accepted the fact that it is a ACAD situation, not a Revit one.

Take care,
Luigi

[Damo]

Do you really think that it would be productive to have Revit developers spend their time developing tools and workarounds for various Autocad work-flows rather then focusing on plugging remaining functionality holes in Revit?Yes, I mean NO!, I mean, I agree, don't waste developers time on workarounds.

Oh, to hear the words of the immortal Leonid putting a priority "on plugging remaining functionality holes in Revit" is sweet music to my ears.

In the words of my other hero, Homer Simpson "Hmmmmmmmm!" :)