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Thread: Creating 3D solid model of underground vaults from wireframe linework

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    Default Creating 3D solid model of underground vaults from wireframe linework

    I have a client who for whom we have carried out a survey of a large area and they now require an AutoCAD 3d solid model of the whole site.
    The current drawing consists of wireframes of underground vaults which sit adjacent to a road/railway and below a wasteland area. We have the above ground topographic survey as a 3d AutoCAD linework survey which we will create a surface of in Civil3d (not sure how this will export) or from 3d contours created in civil3d or our survey processing software "n4ce" which I will loft.

    The most obvious thing about this job is that AutoCAD is not the ideal software for the task, but due to the many problems which always appear when exporting from Max or Rhino we have to do most of the work actually in AutoCAD.

    The end product (if it's achievable!) will look very understated for the amount of work involved in creating it due to most of the intricate detail being hidden away inside the "ground" with vaulted ceilings etc in it, none of which will be visible!

    Where this will come into it's own is that the client will be able to cut sections in it where ever they want to or do volume calcualtions.


    The problem I am encountering is in creating the cutting objects for the vaults which will be used subtract from the main solid.
    The ground of each room is uneven, meaning that I can not easily create a surface for it. I can create a mesh using edgesurf, but this mesh can not be used to form part of a solid (or so I believe). One work around I have tried which works is to explode the mesh into 3dfaces and then create a solid from them using "f2s.lsp" which I found. The trouble with this is that the number of 3d faces is going to end up being massive and the file size too large.
    I have also created the surface in Rhino but it rounds off the corners and it does not quite match our original linework.

    I also need to create a surface for the vaulted ceiling using the existing linework. The arcs at each end of the ceiling are NOT the same, and the opposite walls at the bottom of each arc are not always parallel. Trying to use the two end profiles to create the surface suing the lfot command returns an error messege, so another method must be found. Is there a way in AutoCAD to do this I am unaware of? Rhino seems to work well for this type of surface and they import into AutoCAD as a surface in ACIS format.

    Once I have solved these main issues I feel I should be able to do the rest eventually! Although any suggestions or input is very greatly recieved. I'm hoping that someone like jaberwok can help out here.

    I have included an extract .dwg of some of the date and highlighted what I believe to be the most difficult room to model and also a .pdf of the whole site in an isometric view.
    Attached Files Attached Files

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    Default Re: Creating 3D solid model of underground vaults from wireframe linework

    Quote Originally Posted by mmccarter View Post
    create a mesh using edgesurf, but this mesh can not be used to form part of a solid (or so I believe). One work around I have tried which works is to explode the mesh into 3dfaces
    Stay away from the old surface tools and 3dfaces - use the new surface tools. They are of little or no use for solid modeling.

    Quote Originally Posted by mmccarter View Post
    I also need to create a surface for the vaulted ceiling using the existing linework. The arcs at each end of the ceiling are NOT the same, and the opposite walls at the bottom of each arc are not always parallel. Trying to use the two end profiles to create the surface suing the lfot command returns an error messege,
    The exisiting linework is too rough - simplify with 2d spline. On a project of this size a slight variation between the spline and the already very rough lines you have is insignificant in terms of volume calculation and will make the modeling process possible.

    I played with it a bit but I used an edu version so delete after inspection.
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    Default Re: Creating 3D solid model of underground vaults from wireframe linework

    Quote Originally Posted by JD Mather View Post
    Stay away from the old surface tools and 3dfaces - use the new surface tools. They are of little or no use for solid modeling.



    The exisiting linework is too rough - simplify with 2d spline. On a project of this size a slight variation between the spline and the already very rough lines you have is insignificant in terms of volume calculation and will make the modeling process possible.

    I played with it a bit but I used an edu version so delete after inspection.
    Thanks for your effort and attached file, much appreciated.

    Unfortunately we have to stick very closely to our existing linework, which by the very nature of what was surveyed is rough in places. The most important thing for the client is that they can create sections from the finished 3d model at any location they desire which will be as accurate as if we were commisioned to survey sections directly on site. Volume is as you state, not as important that the linework is followed completely.

    Whilst I can pretty much create any geometry I need to as wireframe lines/arcs, I am only intermediate skill level when it comes to working with solids and surfaces.
    In a way, I am glad that others are not solving this problem as required quickly and easily as it means that I am not struggling with something that others find easy.

    I had a demonstration from our Autodesk suppliers last week to see if Inventor would suit our needs. They think that none of their clients (this covers a lot of the SE of the UK) are pushing the technical capabilities of AutoCAD as much as our company is. Although this is kind of cool to know, it doesn't help us as we felt that Inventor was not right for us at this moment in time but would likely be useful in a year or two.

    We use Rhino sometimes but this is best for surfaces, not solids. We use 3D Max but this does not provide a solution for this job, as do our more advanced programs such as Geomagic and Polyworks. Microstation has it's place for us but this is mostly for transport based clients and there are of course always translation issues.

    I think this one would be a great one to try take along to CAD camp in Birmingham next month.... Now I just need to convince management that it is worth people going since they declined going to AU even though out MD is speaking at it!

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    Default Re: Creating 3D solid model of underground vaults from wireframe linework

    One tip/hint - try to create the shape of each void as a (positive) solid that can be subtracted from the "ground" after you're happy with it. Much easier than trying to create the void directly.
    I believe that, in A2007/8, you can use meshes to sculpt a solid.
    John B

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    Default Re: Creating 3D solid model of underground vaults from wireframe linework

    My plan was as you suggest to create the cutting objects first as solids as this would indeed be easier, but it is this stage which is proving tricky in the places mentioned in my OP.
    It's not possible to cut solids with a mesh in 2007, I'll try in 2008. Thanks

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