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Thread: Volume Computation

  1. #1 Volume Computation 
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    How would you compute the volume of any random feature like in CAD Models where you have open and only partially bound features? I'm looking for an existing methodology rather than a feature of a Software like Internal Volume in Creo.


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    Genius Duck Moderator Dywyddyr's Avatar
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    The hard way: you break down the shape into simpler forms, calculate their individual volumes and then add them together.


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    No, not that. That would only work if I have simple sub parts. For Example, the volume of an Open Bottle. How would you calculate that? Even the simpler parts are not computable like the base of the bottle.
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    Quote Originally Posted by akshayc4563 View Post
    No, not that. That would only work if I have simple sub parts.
    Break it down until the parts are simple. (That's why it's called the hard way).

    Even the simpler parts are not computable like the base of the bottle.
    Really?
    Is the base not, essentially, part of a hollow sphere?
    Calculate the volume of the section a sphere that has the radius of that of the interior (of the bottle) curve and subtract the volume of one calculated on the radius of the exterior.
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    Maybe I wasn't clear enough. You are talking about a simple bottle. Take for example this Coke bottle, the base isn't simple. I'm looking for methods that rasterize the volume into simple cubes to find the volume. Do methods such as this exist in solid modeling (CAD) softwares like Solidworks, Creo,etc?


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    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by akshayc4563 View Post
    Maybe I wasn't clear enough.
    Ah, okay.

    You are talking about a simple bottle.
    Well no... I used a simple bottle as an example, but the principle holds.

    Take for example this Coke bottle, the base isn't simple.
    E.g. the HARD way.

    I'm looking for methods that rasterize the volume into simple cubes to find the volume. Do methods such as this exist in solid modeling (CAD) softwares like Solidworks, Creo,etc?
    You've lost me, you already stated that you're looking for a methodology and NOT a software feature.


    Why would you want to "rasterize the volume into simple cubes" rather than simply query the properties?
    ( I haven't used Creo, but I've used SolidWorks and numerous - dating back to around 1980 - other CAD packages and it's far easier, and less time-consuming, to use the available features).
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    Okay, let me make it simpler.

    So, CAD softwares have a plugin called mass properties (like you mentioned) where in you can calculate the volume of parts. But parts are always closed surfaces.
    But you have Open surfaces like Features of a part, for example, a fillet or a spline surface as part of the feature. Like the Curved Surface of the Coke bottle. For Open surfaces, there is no option in Solidworks to compute the volume.

    About the Rasterization, it is like an extension of Pixelization to find the area into three dimensions. So, I'm assuming that's what CAD softwares use to find their closed surface volume. If not, what could be their methodology. Also, is there an existing methodology for Open surface volume?
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  9. #8  
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    Quote Originally Posted by akshayc4563 View Post
    Okay, let me make it simpler.

    So, CAD softwares have a plugin called mass properties (like you mentioned) where in you can calculate the volume of parts. But parts are always closed surfaces.
    But you have Open surfaces like Features of a part, for example, a fillet or a spline surface as part of the feature. Like the Curved Surface of the Coke bottle. For Open surfaces, there is no option in Solidworks to compute the volume.

    About the Rasterization, it is like an extension of Pixelization to find the area into three dimensions. So, I'm assuming that's what CAD softwares use to find their closed surface volume. If not, what could be their methodology. Also, is there an existing methodology for Open surface volume?
    1) A bottle is not an open feature - it's fully bounded1.
    2) Off-hand I can't think of any software that can calculate volume of an open "solids" (mainly because, by virtue of being open they have no defined boundary2)
    3) I genuinely have no idea why anyone (in engineering) would want to do so.

    1 Unless you've drawn/ constructed it incorrectly - I've certainly had zero problems in obtaining volume/ mass of "bottle-like" solids from SolidWorks (or other packages).
    2 And - open to correction here by the hard-core mathematicians - I'm not sure that it can be done any other way either.
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    Thanks @Dywyddyr.

    I meant a bottle without a cap. (This was just to give an example of an open feature, but generally open features sometimes have just one or two bounding surface like in my case)

    I made an algorithm to do so (For Open Surface). But, my paper was rejected saying "the author isn't aware of the state of the art work in volume computation". So, just wanted to know about them. Can't seem to find anything on the Internet.
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  11. #10  
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    Quote Originally Posted by akshayc4563 View Post
    I meant a bottle without a cap.
    So did I.
    The surface of a bottle (or similar) is closed - the bottle is a fully-bounded discrete object.

    I made an algorithm to do so (For Open Surface). But, my paper was rejected saying "the author isn't aware of the state of the art work in volume computation". So, just wanted to know about them. Can't seem to find anything on the Internet.
    Sorry, like I said, I've never come across such a thing (nor - again from an engineering POV - do I see any requirement for such).
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    Sorry, like I said, I've never come across such a thing (nor - again from an engineering POV - do I see any requirement for such)


    In the field of CAM, you use it to find the volume that needs to be removed to calculate the machining cost and the material wastage.
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    Quote Originally Posted by akshayc4563 View Post
    In the field of CAM, you use it to find the volume that needs to be removed to calculate the machining cost and the material wastage.
    In such cases the fillet (or whatever) isn't exactly unbounded.
    Not least because there's a "defined" start volume and a desired final volume.
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    Quote Originally Posted by Dywyddyr View Post
    Quote Originally Posted by akshayc4563 View Post
    In the field of CAM, you use it to find the volume that needs to be removed to calculate the machining cost and the material wastage.
    In such cases the fillet (or whatever) isn't exactly unbounded.
    Not least because there's a "defined" start volume and a desired final volume.
    I don't clearly understand what you mean. Do you intend to say that, volume of fillet feature= volume before machining fillet-volume after machining fillet?

    If so, we have hundreds of features in a part. Calculating the volume by doing this is time consuming and definitely not accurate in some cases. Because to figure this out, we also need the order in which features are machined. But, ultimately this is what I am trying to find out (the best order, to reduce machining cost)
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    Quote Originally Posted by akshayc4563 View Post
    I don't clearly understand what you mean. Do you intend to say that, volume of fillet feature= volume before machining fillet-volume after machining fillet?
    Initial volume (e.g. the lump of metal placed on the machine bed) - "actual component" volume - removed material1 volume = fillet volume.

    If so, we have hundreds of features in a part. Calculating the volume by doing this is time consuming and definitely not accurate in some cases. Because to figure this out, we also need the order in which features are machined. But, ultimately this is what I am trying to find out (the best order, to reduce machining cost)
    Again, we're back to my footnote: fillets etc should be only as large as necessary.

    1 Because a "real" engineer would only make a fillet (or whatever) as large as it needs to be to do the job it's intended to do.
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