Saturday, March 16, 2019


Difficult to believe that more than 7 years have passed since my first pumpkin posts.  This was the beginning of my obsession with the Conceptual Massing Environment (I call it Point World) which continued for about 4 years, a period of intense learning. You can create some amazing geometries in Point World, but there are also significant limitations and drawbacks.

My ambition was to use these tools to create family objects: sanitary ware, furniture, classical ornament. Things with complex curvature. But there are two big issues: 1 file size, and 2 you can’t nest mass families inside ordinary families. (You can make adaptive components of many different categories, but they will not host on levels or work planes like any other "normal" Revit family.)

In the last post I looked at the potential of Onshape as a solid modelling package for tackling classical ornament, bringing geometry into family editor via ACIS (SAT). This route is also a way to overcome the two main drawbacks of point world. Which got me thinking about revisiting some of my pumpkin escapades.  The Festoon is a common decorative element in classical architecture. It derives from the garlands of leaves, fruit and cloth that used to be hung on buildings to celebrate feast days. There are endless variations on this theme, carved in stone on buildings around the world.

I was reminded of the corn cob I created for my second pumpkin adventure (Snow White meets Arcimboldo)  The overall form is a lofted surface, (formed of profiles hosted on a spline), which is patternised, and populated with a custom curtain panel.  

On Friday, in two sessions of about two hours each, I managed to apply this method to the Festoon motif, with some success. Let me walk you through it. 

The profile is an ordinary Generic Model family with model lines and labelled dimensions. This creates a half ellipse with a parameter to control the proportions.  I usually start off my parameters as single letters, so the formulas look like algebra. Then once it’s doing what I want I will rename the parameters that get exposed to end users using “plain language“  

In this case you get Bulge Factor as a type parameter. Small values will give a flatter shape.  Bulge Factor = 1, that would be a semi-circle. Radius should be an instance parameter to easily vary the size of different profiles, while maintaining the proportions.

Load this into a Conceptual Mass family. Note the grey background and 3d work planes. You are in Point World.  Place 3 points, select them and choose, spline through points. You get something very much like a catenary. If you move any of these points the curve will adapt. They are “Driving Points”.  Now add more points to the line. These will be hosted points and their positions on the line are given by a parameter between 0 and 1 (Normalised Curve Parameter)  We need one in the middle and one close to each end. You can make the work planes visible (show work planes always)

Set the current work plane to one of these and place a profile on the point. You might have to rotate it 90 degrees.   For the GM profile to work in this context you need to reset two checkbox parameters from their default positions.  (Work Plane Based, & Not Always Vertical)  You may have a noticed that I initially had the Radius as a Type Parameter, so I had to change this also.  I have a little trick I like to use.  Place one point, and add a profile.  Select both and copy multiple into empty space.  Select the new points and “pick host”  I find it less tedious than repeatedly going “show reference planes always”, “set work plane” and “place instance”

Big profile in the middle, small ones at each end.  Select the 3 profiles and the spline, then hit “create form“  The result is pretty much a festoon, and it’s a surface. You can select this surface and divide it, then use those divisions to apply a pattern.

I tried the half step pattern and quickly realised that the results were not symmetrical. So best make one half of the festoon, export to SAT, and use two mirrored copies of the results.

The curtain panel family gave me some trouble. New family and choose Curtain Panel by Pattern. Select the grid and choose the type that matches your divided surface. Half Step has 6 points and 6 reference lines.

These families are supposed to keep your design intent even when they are twisted and bent to fit around a surface. So one of the tricks is to host a point on a point and give it an offset. Every point has 3 work planes (XYZ) so you have to set work plane before placing the point. The offset will push it out at right angles to this plane, depending where the point lies on a curved surface.

When I loaded my half-step panel into the surface it kept breaking so I reverted to a square grid. Finally I got some geometry to form... Looked more like a porcupine.

The curtain panels will all be different sizes, so the trick is to use a reporting parameter to drive the offsets. Something strange about this though. The values are much higher than expected. I introduced a global scale factor to adjust all the offsets with one type parameter and just tweaked until it looked right.

Eventually I settled on a panel that’s a blend between two segmental profiles. There are 3 offset  parameters, all calculated a reporting parameter which measures the width of each panel instance. I can’t understand why these offsets would be affected by the straightness of the path that the blend follows (all other things being equal)  

Maybe it’s a bug.  Or maybe I have done something weird with the reporting parameter.  Anyway, my workaround of inserting a type factor into all three equations was simple and effective.

Export to SAT and bring that back into an ordinary GM template. Add a few revolves and it’s looking half decent.  Maybe the tassles are a bit oversized in relation to the central garland.


I need a straight piece hanging down. This was pretty easy. “Save as”, the curved garland and push the middle point into line with the two ends. As discussed above, the panels become very flat. Still don’t understand that but it was simply fixed using the global scale factor “F”.

I intended to open the SAT export in 2014, scale it down a bit, explode and bring back to 2018. (This is partly about applying materials.)  

Sadly some of the panels dropped out on exploding.  So I tried another strategy.

Give the festoon a base plate to sit on, then go to a left side view and rotate the straight garland a bit so the two side rows get buried in the base. Ultimately I should go back and rebuild the massing family, reduce the width of the profiles and number of rows, the re export. But for now this works as a quick fix

Been a while since I fired up Enscape3d. Still working fine, and I fiddled about with Pixlr to come up with the final image.

Already I generated two different curved garlands plus a straight one. Once you have a concept set up in Point World creating variations on a theme is child’s play. Probably need to explore some different curtain panels next. Maybe an attempt at an oak leaf?

In conclusion, recapturing my pumpkin skills could be another way to approach some of those tricky classical motifs. Stay tuned: more to come.

Sunday, March 10, 2019


For the past few weeks I have been recovering from a medical procedure and gradually getting back to my normal routine. That’s one interpretation of the title. Another is that I stumbled across Onshape this weekend, and took my first hesitant steps with this cloud based solid modelling package. I’m using the free version, which means that all my models are in the public domain, but I usually share my work freely anyway so that’s not an issue.

So far I have mostly been using my phone. Works quite well with the s-pen. The desktop version is probably faster (big screen, ribbon menu, right click options) but I like the casual aspect of working on my phone (change of rhythm, work on the move). Nothing spectacular yet in terms of results, but a couple of items that improve on Revit’s native modelling capabilities.

I have a long history of trying to create better geometry for furniture and plumbing families with complex curvature. And in recent years the demands of classical ornament have been a recurrent theme. Onshape has potential in both these areas.

My initial attempts to model scrolls and foliage were useful training exercises that fell short of producing viable Revit families. But I hit paydirt with a spiral, rope motif. Onshape has a built-in helix tool which can be used to generate a sweep. Now it’s possible to generate a spiral with the conceptual massing tools in Revit but it tends to lose it’s shape a bit at the ends and you’re going to have to export to ACIS (SAT) format to get file sizes down.

Onshape also exports to SAT, so that’s the route I’ve been using. Phone to One Drive, open SAT with an older version of Revit, scale and explode, save and reopen in 2018. I generally make families in 2018 now. It’s a compromise between having the latest features and maintaining a minimum of backward compatibility. Exploded SAT becomes freeform or direct shape stuff. Here are some examples of public domain models I downloaded. Surface geometry is going to fail in Revit so results will be patchy.  

You can apply materials, cut with voids, add more Revit geometry.

Getting back to the rope moulding, I ended up with a family that might represent a terracotta tile. A row of these tiles produces a nice traditional linear ornament. I previously developed a system that uses the double nested planting hack to generate repeating linear ornament families that scale parametrically via the height parameter. Sometimes I use railings, but this time I went for line based families.

By the way, I struggled for a while, in Onshape, trying to get the pitch of the spiral to look right before I realised that you need two threads, intertwined.  Just another example of the power of the drawing and modelling processes as aids to active learning. You can look at a shape and think you understand it, but the act of recreating it from scratch is much more demanding and therefore more rewarding.

So flushed with success I decided to tackle the "guilloche" challenge.

This is a motif that has many variations. It’s kind of like a flattened out rope moulding. I guess it’s a play on the whole 2d/3d illusion thing. You can read it as a series of overlapping circles, but like many Islamic patterns, the strap work weaves under and over in a subtle way. I did a Revit version using swept blends but the high point forms a sharp ridge. Onshape gave me a nice smooth loft, based on three profiles. I got a bit carried away with the extra decoration. Often enough you get rosettes placed in the inner circles.

For me, Onshape has a lot of potential, and I appreciate their licencing model. Since I'm using it for personal research, I’m willing to keep everything in the public domain, so I get fully functional software for free and access to all my work on all devices from anywhere with internet.  If you are operating commercially, public domain is not going to cut it, so you’re going to buy a license.  Apart from the secure storage for your work, you’ll get technical support and some extra admin tools.

I know some content creators use Rhino or Inventor to create more complex BIM geometry, but I don’t have access to those tools, so I’m going to give Onshape a try.  Still a lot to learn to achieve a decent level of fluency, but not a bad start.

Friday, March 1, 2019


Hastings is a small town on the South Coast of England. It has a multi-layered history including the famous Battle in 1066 that allowed the Normans to wrest control from a Saxon elite. Fishing still plays an active role in the local economy and makes its presence felt along the Eastern shoreline in the form of black, weather-boarded storage towers and working vessels drawn up on the pebble beach.

I have friends in Hastings who I have been visiting, off-and-on for over 20 years now.  Nick and I know each other from architecture school circa 1970.  He became an architectural journalist and I "dropped out", returning to my northern roots, training as a bricklayer and playing in a band.  Towards the end of this phase of my life, Nick invited me to work on his latest project: a book about squatting.

We had both been involved in the squatting "scene" in London in the early 70s and I had a certain reputation for sketching and cartooning.  I was to be the illustrator, his partner Caroline Lwin was the designer and he was Editor. Various people contributed a chapter each.  Since then he has gone on to become well know in the Community Planning field, writing a handbook and maintaining a website on this topic.

I always enjoy spending a couple of days with Nick and his current partner Jane: relaxed atmosphere, delicious wholesome food and stimulating conversation. This time he reminded me about a book he had showed me before: "Harry the Pencil" based on a lifetime of hand sketching to support design development on an urban scale.

He also brought out another book, called "Design Thinking Drawing" by an Australian architect with a comparable talent for sketching birdseye perspectives, design diagrams, all kinds of images that support the design process.  I was struck by the richness that can be conjured up by a few rapid strokes.  Some of the drawings must have consumed huge numbers of man-hours, but others were rapid and impressionistic, but equally effective.

more examples here

I have been trying to revive my hand drawing skills for 3 or 4 years now, mostly be way of digital tools. I decided it was time to loosen up a bit more, to focus on “fast and fluid“, emphasise the raw energy of an intuitive sketching process. So I spent a morning in Nick and Jane’s living room, working up two views from Project Soane as rapid digital sketches.

Why would I degrade data-rich BIM models, lovingly rendered, into scribbled sketches? What are the positives here?

Audience Appeal: people react well to hand sketches.  There's a warm and fuzzy feeling combined with a certain sense of admiration (I wish I could draw like that).  It's a bit like playing a musical instrument.

Lack of Pretence
: There is no confusion about whether it's a photograph of a real building. People are used to the idea that an artist's impression may take certain liberties.  You don't have to worry too much if some aspects of the image are speculative, or that people will obsess about some minor detail.

I’m very happy with my progress. Two sketches in a morning that also contained a walk in the park and a fair amount of chit-chat. Pretty good progress, and I’m not ashamed to show them alongside the work I did almost 40 years ago at the height of my powers. The image below is from another section page for the squatting book. It was a spoof on a Heineken advert for a section that highlighted how squatters could actually help to raise the profile of a neighbourhood, injecting new life into old housing stock.

My digital toolkit has come of age. I’m showing the gear against a background of bed sheets because that’s where much of the work is done. I can take a break from sitting at my laptop, stretch out and look at the world from a different angle.  We are mobile beings who settled down and built containers for our lives.  Keyboard and mouse belong to that urbanised identity.  Touch interfaces recapture something of the hunter-gatherer lifestyle.  Just a thought.

Switching images between mobile devices via the cloud leads naturally to integration with the social world we all inhabit. My immediate family is spread at regular intervals from NZ to Florida, by way of Singapore, Dubai, UK. The more fluid my sketching becomes, the more likely I am to share family moments using that medium, it’s more personal and allows me to strip out irrelevant detail. Pretty much the same qualities that appeal when presenting design ideas or analyses of historic buildings. This next one is from a very special last morning with my grandsons during my most recent visit.

I’ve been dealing with a medical issue since just before Christmas. I couldn’t get the operation I needed in Dubai, so I returned to England for 3 weeks. The visit to Hastings was part of my recovery period. I didn’t get down to the old town this time. These sketches are based on pictures I took with my very first digital camera in 2002. I was visiting from Zimbabwe with my son who was on a gap year. Both of us were about to go through a series of changes though we didn’t know it.

Digital photography sat beside CAD for a couple of years. Sketchup came along and shook things up a bit. Zimbabwe went down the toilet, Joe was studying in Cape Town, I decamped to Dubai and got my hands on Revit. From Dubai I have been able to travel more frequently, building up a database of images, including those early ones of Hastings. It’s part of a project I call “the way we build”... Just a set of reflections on what it is to be human, using the buildings we make as my point of departure. 

Hastings Old Town is one of those places that seems to have grown organically: houses in a range of styles and materials tumbling down hillsides and setting up an endless series of picturesque viewpoints.  Tile cladding, weatherboarding the black and white rhythms of old fashioned timber framing, projecting floor joists that allow the upper floor to cantilever beyond the ground floor footprint, leaded glass in diamond patterns,  It's the kind of place that's very difficult to model convincingly using BIM tools, but looks great in a hand drawn sketch. 

There is something organic about Peter Richards’ work, his "Design Thinking Drawing"is very rapid and process oriented..

He observes, he imagines, he analyses. The Hand-Eye-Brain continuum churns through material rapidly and effortlessly but with results that often surprise and arrest. It’s a search for meaning, as is the way I’ve been building digital models, collecting photos and plans, reading historical accounts, blogging... and increasingly sketching ... different ways of exploring towns and cities around the world. Consider this wonderful evocation of Chicago by Harry-the-Pencil.

When I got back to Dubai, I discovered that Harry’s book is available online.


I’ve talked to Nick a few times about the potential of BIM to add something new to urban planning processes.  But is it user-friendly enough?  Think about the power of hand sketching to capture ideas quickly and win over the hearts and minds of local residents.  How can we inject this kind of fluidity into BIM processes?  I don’t think we quite know how to bridge that gap yet.

I remember spotting the chance to take a shot of a seagull, perched on a chimney, with the seafront in the distance. It seemed to capture something about layers of meaning and the richness of urban life (Hastings old town).  The parallel world of birds and insects that make incidental use of our buildings. The all but obsolete technology of open fireplaces that stimulated the coal mining industry in England, making possible the industrial revolution.  The pier in the distance, since burnt down and renovated in much simpler form, complete with salvaged charred timbers, reused in inventive ways.

Digital photographs freeze moments from our past at a phenomenal rate.  On a good day out in a new city I will collect about 400 images.  When I bought rolls of 35mm film, a dozen snaps would have been a very extravagant day.  Is this akin to the invention of writing, or the printing press?  Suddenly we have external tools that bolt on to the evolved memory system in our head.  We can store up knowledge and experience in new ways.

I guess the first drawings and clay figurines were similar leaps forward (or sideways) taken many thousands of years before writing began to appear.  So here am I fusing drawing and modelling with the digital realm, trying to inject the raw power and fluency of ancient artistry back into my work.

A luta continua.  The struggle continues