Tuesday, August 02, 2011

Revit 2012 – massing & voids

This may seem rather obvious to the seasoned Revit user; but for the new kids on the block, when using voids to cut massing geometry in Revit, sometimes you need to think a little differently. The process of using voids to cut geometry can be a bit confusing. This is especially so, since the way voids cut in the conceptual massing tools is a little different compared with voids in say the in-place editor or family editor.. For instance, take a look at the image below. This was created by generating a freeform surface using the massing tools….then roof by face to generate the actual geometry for the roof.…it looks reasonably straight forward to achieve, but you need more then two voids to cut the initial massing surface.

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Let me explain in more detail….. image

So the surface was created using the massing tool, which consisted of a series of spline reference lines, then a surface generated between the reference lines. As indicated below.

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Next up, a inner boundary & a outer boundary of reference lines where sketched. These will be used to form the voids which will cut the surface.

image

Now the natural logic here is to also create a large rectangle to go beyond the surface, like this…..

image

However, this is not going to work for us, because if you try & build the void, from the rectangle & trimming reference lines you are going to get the dreaded “Unable to create form element error”.

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Instead, you need to create two voids from reference lines to cut away the excess surface. With a reference lines configuration like this.

image

The image below, hopefully explains it a little better.image

All we then need is to create a void from the inner reference lines to cut the opening & we are good to go.

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You may need to use the Cut Geometry tool to force the cutting.

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I hope the above makes sense, I guess I should really do a youtube video to explain it in more detail, but this should at least give you some useful guidance.

4 comments:

Autodesk Revit Solutions said...

Hi David, here Phil from the Student Experts TU Graz, we are wondering if there is a possibility to create the bejing Birdsnest in Revit. We have been trying it using several different methods eg. using sweeps revolves mass Faces and adaptive components but we were not able to create a form that was like the original. Do you have any idea ?

cheers phil

Vương Đạo Hoàng said...

Great! Thank you. Small step saves our time.

TheRevitizer said...

it's very interesting but if it was a video tutorial it would be much more useful to me. thanks anyway.

TheRevitizer said...

hi please how did you fill the void inside the surface with those metallic bars i mean i couldn't create roof from surface in this area.
thanks