Sunday, January 15, 2012


One of my little hobbies is to plug away in areas where Revit is notoriously weak, in the belief that things are not always as bad as they seem.  For example my attempts to create better families for toilets & washbasins.  Stairs and railings are also obvious targets.  Another common complaint is the lack of tools for creating roads and footpaths.  There is a 3rd party plug-in that you can buy (Eagle Point).  I haven't had a chance to try it out but Aaron Maller has done some very interesting work with it.  malleristic revitation

My challenge for last weekend was to try to squeeze some extra performance from out-of-the-box tools like ramps, floors & railings.  Revit ramps are a mixed blessing.  They rarely display as you would like them to in plan views, which I find very puzzling.  Like stairs they are designed to go from level to level using preset rules, which makes them a bit cumbersome to use as footpaths.  But let's try.

Imagine a drop-off point on a slope.  The pavement around the edge needs a kerb and a set of regularly spaced bollards.  The first point to note is that risers are divisions between sections of sloping ramp and flat landing. To go from straight ramp to curved ramp you can omit the riser or place two risers in the same place.  Oddly enough the second option works better.

The fill pattern on a curved ramp will adapt to the curve. A square grid becomes a radial pattern for example.  Also the railings will follow the slope of the curve very nicely.

But if you use a floor with a slope arrow, the grid remains square & the railings won't quite match the slope.  You can see this clearly at the junction between floor & kerb.  The kerb is a simple rail, and the bollards a series of balusters.  You can force the slope arrow to follow a curve using the pick option, but it makes no difference, the floor will remain flat, and the bollards will float above it in the middle even though they touch at both ends. 

Also take care how you draw the railing.  The slope is determined by the start and end points of each segment.  In this case, rotating the sketch by 90 degrees creates a very different result.

 The shortcomings of the ramp tool are well known.  You need to do a lot of drafting to get the appearance you want in a plan view, and in section it's probably worse.  There is no "edit structure" to add a finishes build-up and no "join geometry" to clean up the junction with the clever railing you invented to emulate a curved parapet wall.

It's great that they have the intelligence to respond to maximum slope settings and automatically prompt you into placing landings at the stipulated intervals.  Could be a great tool with a little extra functionality.  But stairs & ramps both suffer from one of their common strengths.  They are defined in relation to levels.  That's fantastic most of the time, but if you want to use them as landscape objects it becomes an annoying restriction. 

 So for a road flyover that has varying curves & gradients I choose ... in-place modelling, yet again & that wonderful invention that we got so excited about in the days before conceptual massing THE SWEPT BLEND.  Make a profile for your bridge cross-section.  Use it in a series of swept blends and tweak the curves and the levels of each profile to your hearts content.  Not very hard to create graceful bridge forms with a bit of practice.

 Almost looks like Dubai.  Notice the W-beam crash barrier.  Make yourself custom railing profile & baluster post families, define yourself a new railing type and away you go.

The quick and dirty solution for roads and footpaths is the topography subregion.  No kerbs of course, but they will follow the terrain and they are quick to make.  Also nice for golf courses, cricket pitches, flower beds ...  Pads are better for water of course because liquids tend lie flat.

At this point I was having so much fun I got a bit carried away and tried to make an adaptive family for a fence that would curve and swoop, twist and wind ... imagine the possibilities. 

Step one was a very simple mass family.  Just a vertical line with the "always vertical" parameter checked (family category & parameters)  Load this in to another mass family and host a bunch of them on adaptive points.  I figured out how to lock them in place so they moved up and down as a unit.  Fantastic.  Select the lines, create form, divide surface.  Problem solved.  (not)

Worked fine in the family environment, but that is not always a good indicator.  Soon as I loaded it into a project it broke.  Almost broke my heart.  But then I had another thought ... what about modelling in place ? 

So I followed the same strategy but this time all the adjustments are done by editing the family, so no opportunity to break.  I was so chuffed.  The posts and rails are curtain panels by pattern of course, based on the rectangular template. 

One day I will get round to exploring a range of different fence styles by setting up different panels, but for now I will quickly skip forward to my last brainwave of a rather productive weekend: image processing without rendering.  Not the answer to every situation, but could be a useful timesaver, and there is surely potential for batch exporting plus some automation within the image editor.  Could become a veritable production line & all thanks to "realistic" views.

I'm not a big fan of the realistic view.  Tends to look garish.  Somehow the material settings that work well for rendering are often too strident when viewed in "realistic".  But that's exactly where a bit of image processing can help out.  Combine a realistic with a shaded or hidden line, use an overlay setting, some transparency and/or an artistic filter.  Instant touchy-feely ... what more could you want ?

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