KAK HANDED

Sadly this is already more that a week old.  Read on.

It's been a bit of a disastrous few days for me.  Maybe that's putting a melodramatic spin on it, but firstly I am recovering from a very sore shoulder which seems to be a result of posture and mouse use.  I actually spent the last day of the week trying to use my left hand.  Interesting, but very clumsy.
It makes me realise how much of my time is spent in dialogue with a computer screen.  It's been extremely wierd spending a three day weekend almost completely ignoring my laptop. Which brings me to the next catastrophe.  The wonderful new laptop I received from HP as a reward for my work on Project Soane has suddenly stopped working.  Fortunately I have my old machine and just about everything is backed up via OneDrive, but it still feels like a mortal blow.

One of the things I did with my left hand, was to make a task chair family.  I came across this thing called the "Trinetic" which offered a download of drawings and images.  I thought it looked quite sweet, and decided to remind myself how to convert a 3d mesh into a useable family via 3dmax (and Autocad)  I had forgotten, but was able to follow my own post from early 2016.  Basically it's all about hiding the edges of the polygons.     be-gone-sharp-edges

There will be the usual complaints about nested CAD, but I am over this now.  You can't model something like this convincingly with Revit native geometry.  It's not the kind of shape that those tools were designed to make.  Here is a nice smooth version, all ready made, so let's use it.  Solids are great for things that need to be sectioned.  That doesn't apply to furniture. Mesh is the way everyone models this kind of stuff for visualisation, movies, etc.  The minute you try to get half way to modeling these double curved shapes with native tools there's going to be lots of gymnastics cutting with voids and the file size will shoot up.  Really, I love some of the stuff that has been done for people like Herman Miller, but looking through that again, there is nothing that comes close to the smooth flowing tapered curves of a chair like this. 

Add to that the whole "cross-platform" debate and I just don't see the point of turning your noses up at mesh geometry.  Revit can handle it.  We know how to hide the edges.  File sizes are very reasonable.  So if someone has already done the modelling for you as a CAD mesh, gobble it up.
Having hidden the edges in 3dmax, exported to DXF2014 and resaved as DWG, I inserted the mesh into an RFA template.  For the most part the geometry was already sorted into layers by material.  I just had to put the wheels on to a different layer.  The layer names weren't very helpful, so I renamed them in Object Styles, which is of course where you go (within the project environment) to apply materials.

Revit has this habit of creating a bunch of materials with dumb names (Render Material 0-0-255, etc) I like to delete all these. Then I usually apply some of the default materials to the layers, just to give some definition to the family, which will also show up in the thumbnail.  I use the default materials because I believe in sharing with the global Revit community, and I don't particularly want to inflict my material naming conventions on everyone else.  It's called being polite.

Here's how my cleanup process in Object Styles played out

The next point of controversy is the use of symbolics.  I'll state my position once more.  I like to be able to produce crisp linework on sheet sets.  Maybe it's because I grew up drawing by hand, maybe it's because I think people respond better to visual communication that delights the senses.  Look at web site design, advertising, company logos, product packaging.  We have a sense of beauty and elegance, and we are subconsciously influenced in positive and negative ways.  "Old Fashioned" ideas of draughtmanship and layout do matter, whether you are trying to sell a design to a client, or communicate intentions to a construction worker.  So messy, fuzzy edges to furniture objects in my plans and elevations really bug me.  They also bug senior management who don't need to have their negative prejudices towards BIM confirmed.

In short, I may be working left handed at the moment, but I don't want my families to look like they were drawn that way.  So I have chosen to create crisp linework and masking regions in the 3 orthographic planes.  Revit doesn't make it easy for me to differentiate between front and back elevations, but usually front will do fine.

Here I am going to agree with the CAD haters.  There are 2D CAD files in the download, and it would save a bit of time to use these, but I want to have masking regions anyway, and I usually find that manufacturer drawings show too much fine detail for architectural purposes.  I'm not going to be using these at a scale of 1:5.  I want them to look right at 1:20 & 1:50. So I am redrawing and simplifying as I go.  I have also introduced a certain amount of "coarse-medium-fine" differentiation.  It's quite subtle, but might as well do it while I can.

But what about the 3d geometry? Do we need 3 versions? I suggest not.  I hate the all-purpose boxes that are so commonly used.  What's the point if you can't tell whether it's a chair or a WC?  But it may be worthwhile using 3 simple extrusions to represent a generic task chair.  Have that for coarse 3d views and the CAD import for medium and fine. Use symbolics in plan/section/elevation.

Finally I tried a quick render ... could this be another downside of meshes?  Seems like the seat is distorting render bitmaps in rather strange ways.  The back is fine, so maybe it's not meshes per se that are the problem.  Might be worth exploring that a bit more some time.  In any case it's only really an issue with large scale patterns like the striped fabric.
Anybody else want to help make families like this from available 3d CAD?  Fancy a bit of crowd sourcing?  Or maybe we could make some "collections" up ... like this one I assembled from an Italian furniture maker that I stumbled across.  Seems to me that even half a dozen experienced Revit users willing to cooperate on something like this could significantly improve the range of content available online.

link to my version of the Trinetic chair

HERE

(sharing of this link should now be fixed)

By the way it's about 900kb which is much smaller than it would be if you tried to do this with Revit native geometry. even if you accepted lots of sharp edges where this is nice and smooth and rounded off.

Oh, and while we're here, Kak-Handed, or Cack-handed as some would have it, means left handed in the part of the world where I grew up, and my association comes to mean "incompetent"

On that note, here's a recent quote from a government minister in my home country of Zimbabwe, and I can assure you it was said in all seriousness.

ALTERNATIVE LINK - FRITZ HANSEN FAMILIES

Back in April I did some work on incorporating mesh geometry into Revit families in such a way that the horrible spiders web of black lines is not visible.  This can be very useful for certain kinds of object that are available for download as mesh geometry but very difficult to model convincingly in the traditional family editor.

As an illustration I used the justly famous furniture designs by Fritz Hansen.  At the end of that post I gave a link to a Revit file of this families.  Apparently some people have been unable to access this link, which was on A360, so I have added an alternative link.  In case you had this issue, try downloading from here.

FRITZ HANSEN FAMILIES

FREEHAND CHAIRS

Continuing with the theme of Rigs for lofting profiles in Point World, this is what I call the "Freehand Spline" rig.  It's freehand in the sense that not everything is subject to dialogue box control.  To make some kinds of changes you have to open up the family and manipulate it directly.

I grew up with freehand drawing, so I have no problem with that.  Parametric dialogues are great in their place, but there is still a lot to be said for the direct, intuitive approach.  Witness the success of finger poking devices in recent years.

I wanted to represent a type of chair that is very common.  It might be bent plywood, or it might be moulded plastic, or it might be something softer.

You could make a reasonable go at it in Vanilla using a sweep tapered off at the ends with void cuts.  I've chosen to do it in Point World which offers a slightly more elegant solution and allows more subtle variation to the shape.  The profile I used for my first example can be varied in both width & curvature.

So the chair is more curved in the middle where you sit, and rather flatter at the ends.  This is most evident in a side-on close-up.

I experimented with a few different profiles.  Most of the complex profiles refused to "create form" but eventually I found one that gives an upholstered cushion effect, based on a 3d spline and a straight line.

This varies quite nicely based on a single width parameter.

The irony is, that the most elegant form to acrue from these experiments is based on a rectangular profile and could surely be made quite convincingly in vanilla.
The base is lifted straight from the space chair that I featured a couple of weeks back.

So what are the advantages of Point World in this particular case ?

First of all there is the ability to modify the spline directly and get immediate feedback on the resulting shape.  In Vanilla you would have to "edit sweep", "sketch path" make the changes, "finish path" & "finish sweep"

Secondly you avoid the need for at least one void cut to taper the back of the chair (two if you want to taper the seat slightly also)  Apart from appearing rather clumsy when selected in family editor, these cuts inevitably leave small seams on the edge of the seat.

So for the sake of experimental completeness I decided to make 3 versions of this chair.  The first is based on the adaptive template. It's the first one I showed.  The second is pure vanilla, with void cuts, as above.  The third is vanilla, but the seat is taken from point world version, exported to SAT, reimported and exploded.

The adaptive version can be opened up in family editor and the shape adjusted using Point World techniques. On the down side it behaves strangely.  It will not respond to the level & offset parameters in the properties dialogue.  When you press space-bar, instead of rotating 90 it jumps several metres to one side.  On subsequent presses it swings around in a cirle, returning to base on the fourth press.  You can avoid this be making it as a mass family, then you just have the "wrong category" problem.

The pure vanilla version works fine, but I find it hard to love those orange voids that jump into life whenever you touch any geometry.  "Crude but effective" seems apt.

I thought it might be fun to round the edges off using "pick-edges" mode for a void sweep.  Would have been exciting if it worked, but it didn't.  You can round off one side at a time, but this leaves an awkward little gap at the end.  Also attempting to add the next side yields one of those "circular chaing of references" errors.

It is possible to add a bullnose edging using "pick-edges" but no use trying to "join geometry" to hide the joint line. Destined to fail.

My next brainwave was a thicker rectangle with an edging that mimics upholstery. This worked fine.

So why not make the seat less flat, thinks I.  Turns out that a double hump refused to loft itself along a spline.  One node too many.

The lop-sided nature of the "4 node" curve is a little odd perhaps, but beggars can't be choosers.

It turns out that you can delete the seat and the edging remains intact, which is just as well because the new geometry won't take a "pick=edge" sweep.  You can copy-paste between families to drop a curvy seat into a straight edging.

The difference is extremely subtle, even when you exaggerate the curve. The eye is fooled by the straightness of the edge I think.  Using a patterned material makes the curvature more obvious, but is it really worth it ?  I'm not sure, but I'm determined to keep trying to generate furniture families with a softer look.

It seems that the edging is the most expensive piece in this family. File size more than doubles.  So I tried ditching the edging and cutting off the ends with a curved void.

I went on to experiment with 2 solids hosted on the same spline. Also attempted to reduce the "flat end" effect by grading the profile size down in a series of countours.

And that's the end of my freehand wanderings.  Nothing very dramatic in terms of end results, but an interesting technique all the same.

OUTER SPACE

When I was looking for everyday objects to model in point world (for my RTC presentation in Chicago) one of the first pieces of furniture that sprang to mind was the Space chair.  A Fritz Hansen original, much copied, classic use of moulded plastic sheet.

For the longest time I couldn't figure out how to make it.  I kept trying to see the form as a series of profiles hosted on a spline, but that turned out to be really clumsy.

Then one day the penny dropped.  Actually you don't need Point World.  The underlying form is a blend.  It's like one of those thached roofs that are round at both ends with a straight ridge in the middle.

Flip that upside down, at an angle.  Make a similar void, slightler smaller, cut away and you've got it.

Well it needs to be trimmed around the edges of course, but that shouldn't be too hard.  So I started with a profile.

The swept blend was a wonderful thing when it was first released, then a year later it got overshadowed by Point World and I've been neglecting it ever since.  First insight.  You can do a swept blend with a straight line.  Why bother ?  Because it allows you to use loaded profiles, something that ordinary blends don't accommodate (perhaps they should)

Using a straight line as the path for a swept blend gives me lots of control, easy to adjust the length and angle.  The profiles are parametric, easy to adjust their sizes and proportions.  I was using a CAD download from Fritz Hansen as a guide to get the size & shape right.

My first attempt to trim the edges was awful.  Second go was much better, but you can still see sharp edges when you zoom in close.

I decided that I needed a void blend.  Now you can make a void extrusion with a hole in the middle, but that won't work with a blend.  You can only have one closed loop at each end.  No donuts allowed  ... unless you leave a little sliver of a gap somewhere so that actually it's just one loop.

That's what I opted to do.  Not very elegant, but it works.  I leaves you with a spike of plastic sticking out sideways as if the shape had been injection moulded rather than pressed from sheet, but with care you can clip this off so that it's barely noticeable.

Now for the cushions.  I had a quick go at making these in Vanilla also, but it was never going to work, so I'm back in point world after all.  I isolated the cad object for the cushions.  It's a mesh.  Maybe some of you know how to convert this into a solid that will come into Revit and explode nicely.  That would save time, but I've never figured that one out, so I'm going to make if from a series of profiles ... in Point World.

I decided to set up a series of reference planes that slice through a cushion.  They don't actually cut it of course, but I can host splines on these planes and adjust them until they are pretty much sitting on the surface.  A bit tedious, but it was an interesting exercise.

I'm using conventional 2d splines here, the kind that stay resolutely on the reference plane you put them on.  So the only ref points belong to the straight lines that are used to close the loops using 3d snapping.

Use create form on the first 2 or 3 loops. Then progressively add more to create a reasonably convincing replicat of the CAD cushion.

You can easily see where your surface is proud of the original and where it dips below.  Select the nearest spline, look for a node, adjust to your heart's content.

There's always going to be a flat end where your last profile sits, but you can make this very small, or you can just decide that it's not going to show up, especially if the cushions are black, which they often are.

When exporting to cad from a family, your temporary hide/isolate settings are respected, so it's easy to push this out as an SAT solid.  Open this in autocad and you get a chance to round off the sharp edges.

Import SAT back into Revit and explode.  Now it's free-form native geometry and you can apply a material parameter.

The base is pretty straightforward to make so I won't go into much detail.  It helps to set up a ref plane with a parallel section plane when creating the extrusions for the legs and the revolves at the end where they attach to the plastic.

You might think that this results in a heavyweight family, but it's just over 1mb.  I'm not going to spray hundreds of these around anyway. There are a masking regions and symbolic lines to represent the object in plan views.  Interesting to note that the "free form element" for the cushions doesn't trigger a "visibility settings" button on the ribbon.  Fortunately you can turn it off in plan views via the "Visibility/Graphics Overrides" in the properties dialogue.  Another case of inconsistent terminology for Steve Stafford's record book.

I've turned all the 3d geometry off in orthographic views and at coarse detail level.  That should handle most performance issues

For the front & side elevations I used the CAD objects kindly provided by Fritz Hansen.  Just added a masking region.

Hope you found that interesting.  Download the family here


.Space Chair Download

I'm going to finish with a gag reel that illustrates the follies of cleverness.  More failed attempts to create the space chair using Point World gymnastics.

Along the way I developed the most complex trigonometric formula I have ever devised for Revit. (not saying much)  But none of the results lived up to expectations.  What a waste of effort.

Or maybe not.  Sometimes the simple solution will only come to mind after a long & difficult search.