View Full Version : Square Foot Take-off using .dgn file
2010-04-28, 11:53 PM
I am trying to estimate the entire exterior square footage of a building to determine parameters for a building pressure test. My company is commissioning the building, and we have access to the designer's drawings, but they are .dgn. I use AutoCAD MEP 2010, and have Revit MEP 2009,10 & 11. Is there a way to import a .dgn into a Revit model, and once there, can Revit determine the square footage of all exterior surfaces of the building? I am very proficient in 2D AutoCAD, have limited and frustrated experience with Revit (but I keep trying), and know absolutely nothing about Bentley Microstation, except that it uses .dgn format, and that I can import the files with AutoCAD or Revit. I am having trouble with the importing into Revit 2010 right now, and the last error message said that I had an incompatible .dgn format. Before I go through the trouble of trying to get this to work, does anyone know if or how Revit can determine exterior square footage?
My other option is to print .pdfs of the elevations, floor and roof plans, and get out a scale. I know it works, but it seems crude given how powerful modern software is.
2010-04-29, 04:24 PM
My other option is to print .pdfs of the elevations, floor and roof plans, and get out a scale. I know it works, but it seems crude given how powerful modern software is. Well I wouldn't go that far. But yeah your not going to get much out of the import besides a visual.... 'bout all it's good for is tracing/underlays. If it's a 3d dgn... it worthless for plan views as Revit doesn't cut through any of it. You could model via trace of dgn and schedule areas... or you could import to the program of your choice and measure areas via area tool of choice (Revit's tool is filled region for areas on elevatations). Either way will be more reliable than a scale and manual calculations.
2010-04-29, 05:44 PM
Thanks for the info. Sorry I posted this in two places, I didn't realize 'Quantity Take-off' was another Autodesk product. I don't think I'll be able to trace the model this time around, as I know nothing about creating roofs in Revit, and this particular building has 3 different roof levels, multiple odd slopes as well as two flat sections. I will have to get on board and figure out the building modeling features of Revit before the next take-off comes my way.
2010-04-29, 05:51 PM
Very much worth the time to learn. especially should something change that you'd need to redo a bit of the take off. Lots of help here on AUGI should you have any trouble. So this time around I'd probably import 2D views into program of choice and measure away. I'd prefer Revit since you can have multiple areas "stick" so to speak and not have to remeasure via area measure tool.
Also you should know Autodesk QTO has a couple real nice features to do just this on dwg, dxf, dwf, and pdf if I remember correctly.
2010-04-30, 05:32 PM
Ok, so I imported the .dgn using ACAD 2010, and exported it to .dwg. The file was very messy doing this, So all I got from it was to trace a polyline around the perimeter for my floor area. I used the avg. wall height and calculated the wall areas. Then there is the roof with a number of calculations for the flat and sloped areas. I came up with a very rough figure this way. I am now trying to create the building in Revit MEP 2010.
.dwg underlay - trace the exterior walls (set to exterior, not center) - EASY!
create floor slab - PIECE 'O CAKE!
create roof - by foot print. - error message - you can't create roof by foot print. wtf?
I am starting over, but I am remembering that Revit likes it when you create a view for everything you do. There is no default template in MEP to just create a building with no systems. I suppose the years of creating templates for all situations is when Revit really starts to pay off.
2010-04-30, 05:45 PM
no template needed for what your trying to accomplish. Yes, imports/exports are messy in general. I've been out of the AutoCAD game for quite a while (heck I didn't even know AutoCAD read dgn), but I would think if you have a 3D dgn you could just bring that into Revit and create some elevation view to do a take off of walls via filled regions. But since your game for making a rough model I'd of done the same and created a 2D layout to import to Revit...Revit and Roofs is like learning a fine art depending on the roof your working on. Without seeing your roof and it's complexity, I can only offer wild guesses as to what your having trouble with. Are your eaves all aligned? If you have many complex slopes, can you break it up into smaller pieces for Revit to build?
2010-04-30, 07:12 PM
I didn't even know AutoCAD read dgn
It didn't always. It was a feature I noticed in 2010, because we don't have bentley and sometimes all we get for drawings is .dgn and .pdf. Developing a background from .dgn is much easier than using a .pdf, but it's still a pain.
I would think if you have a 3D dgn you could just bring that into Revit and create some elevation view to do a take off of walls via filled regions.
I haven't seen anything 3D about this dgn. When I last used Benleyview to open it, I couldn't see anything besides a floor plan. Now that I've imported it in CAD and exported it to .dwg, it's 2D only.
Revit and Roofs is like learning a fine art depending on the roof your working on.
I agree. It seems as though, in this case, that it is an abstract work, open for interpretation.
Without seeing your roof and it's complexity, I can only offer wild guesses as to what your having trouble with.
The only full set of plans I have is from .pdf, and after looking at them, I am down to wild guesses as well. There are several inconsistencies with the elevations compared to the floor plan. There are sections of the clerestory that are shown open below, with no walls to support them. After much confusion, I asked an engineer for help. He asked "is this a 50% submittal?" "no, this is 100% CD package" "well these plans are garbage." The larger issue, for me, is when an Architect generates bad plans, I have enough experience to work around their mistakes in CAD. Revit isn't as forgiving.
Are your eaves all aligned? If you have many complex slopes, can you break it up into smaller pieces for Revit to build?
I didn't know I needed to create eaves. I am trying to break it up into the sloped sections, the tower, 2 clerestory levels, and the majority of the roof which is flat. Again, I'm having trouble learning Revit because I'm used to the simplicity and accuracy of CAD. There are 6 CAD users in our office, and no 2 of us draft the same way. I can think of 6 easy ways to create a 2D square. Revit seems like there is only one way to do things, and it's somewhat un-intuitive from what the ribbon suggests.
I also know that I am trying to create a building with no experience in Architecture, and less with Revit. My shortcomings are snowballing off of lack of experience in Revit, my affinity for AutoCAD, and in every circumstance that I've used Revit, bad drafting or design practices from an Architect.
Previous experiences include:
Multiple links to a single model, with 'Level 0' at 0'-0" on each link, and 'Level 2' at various elevations in each link. When I realized that the first step (as I was trained by an Autodesk Training Center) was to copy/monitor the levels, which wasn't possible, I gave up on the design and proceeded to fudge it, placing pipes about where they should be.
(the Architect didn't think having level 2 at multiple elevations was a problem, so I don't think they cared that the Pool piping was an approximation)
A single story building with 20 levels. Not kidding. The levels were all named by number, and they were not in ascending order. Level 12 was 100' above the building, Level 5 was 10' under ground. I only had to use that model to print a reference floor plan.
Granted, this current job is involving a .dgn file, but even their stamped .pdf set has dimensions that are not connected to anything, just 'floating'.
Wow, that rant was longer than even I expected.
DTB, thank you for your help, you seem to know what you're doing, and I wish I had the opportunity to work with you and learn some more about Revit MEP and what an Architectural Model is supposed to look like. For the time being, it seems as though all I'm going to get are curve balls.
I have to go ask my boss if it's better to get fired for not learning Revit or for spending another 8 hours on it with no tangible results.
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