Issue with the placement of CAD files (Import DWG from GeniusLoci)

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#1

Hello, this is my first post.
I am trying to make an automatic workflow to load and place CAD files into Revit using the pack GeniusLoci. The Revit version is 2018 and Dynamo 2.0.3.
The main idea is to take the drawing from a CAD file, using only the drawing itself and the position of the origin XY as a reference for the project base point.
To accomplish that i am using two nodes of the pack, Enumerate DWG import options for getting the necessary information to feed the options, and Import DWG for making the action.

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But it seems that the function Placement of the node Import DWG does not work as it should be, placing the drawing in a strange location of the Revit project.
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Using both Site, Origin or Shared gives me the same problem. Only when i use Centered, it works as the node says.
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I have checked the units of the CAD and Revit (i work in meters), and also the placement options from the node itself.
The only temporary solution that i have found is drawing a circle in the CAD, with the center at origin XY, and with radium as long as the “furthest” point of the drawing, then using the Centered option of the Import DWG, forcing the imported file to the center.
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But in a practical way, it makes the workflow essentially less efficient, because you need to make that circle in each drawing, and for large projects with dozens of drawings is a tedious task. So i am glad to hear what i could do.

Thanks for your time,
Damian.

#2

Sounds like a coordinates issue.

#3

what do you mean?

#4

Hi,

Did you try the Placment options with the user interface in Revit (Import DWG button) and what was the result ?
Did it work ?

#5

It looks like you’re placing the origin of the CAD drawing at the origin of the Revit model and not taking into account the project or shared coordinates. You would need to know where your model is located in order to place the CAD import at the same place. You should be able to shift your import point based on the coordinate system you’re using in Revit.

#6

No, it did not work. Only works when i use the Centered option.

#7

I just tried with the traditional way and surprisingly gives me the same result. So you are probably right. But i do not understand how that works, so what should i do next, step by step?

#8

The Revit origin is based on an internal coordinate system. You need to know where your project is located relative to that origin. The first step is getting your CAD origin and whatever coordinate point you’re going to use in Revit (project base point or survey point) in the same relative location. So that the model/drawing will lineup. The second step is finding the translation of that point from the internal origin in Revit. If you use the project base point this should be as simple as the coordinates for the point itself. That’s where you would want to place your CAD drawing.

Hopefully I’ve explained it well enough but I’d recommend looking into Revit coordinate systems and trying to understand how they all tie together and what they actually do. This isn’t just an issue with CAD files, but any Revit import you may deal with.

#9

Sounds tricky, but it seems to be the only way. That was helpful, so thank you.