How to Get your City into Revit (via Flux Site Extractor)

Did you ever find yourself in the position where you badly needed the surroundings of your project but didn’t have any? That’s right. My heart goes to our fellow surveyors, but sadly enough you rarely ind yourself in a position where clients are willing to pay handsome money merely to give you what you need in order to work on your project. Life ain’t easy.
Therefore, usually you find yourself cursing horrible curses while you model randomly with less than scientific data taken from Google Earth.

You might as well hit your computer with a club, for the good you’re doing.

Well, you always had alternatives. A couple of them have already been illustrated by my BIM manager here and here. One of them involves Dynamo. The other one… well, the other one involves a lot of lateral thinking. Should those n0t be enough, our buddies at Flux recently provided us with yet another way and it’s called Flux Site Extractor. If you don’t remember how Flux works, I gave you a brief yet painful example of application here and I’m not going to do it again.

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– What does Site Extractor do? –

What you always dreamed of while looking at Google Maps: it gives you access to all that beautiful data, in terms of terrain, buildings and streets.
I’m not kidding.

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– How does that work? –

Well, first of all I suggest you register on Flux (not explaining again, as I said). Then, go straight unto the Site Extractor and pick your area of interesti by searching in the tab on the right. For simplicity’s sake, I’ll do my experiment with an area nearby the office. If you allow Flux to look at your current location, you’ll get your office too as default. And nobody cares where you work, trust me.

In the right tab, you can also turn on and off the different set of datas you want to export.
– Building Footprints will export just the… well, the building footprints, in 2d;
– Building Models will export the accurate and surveyed shape of buildings;
– Topography takes care of terrain, where available;
– Contour Lines is for topography, of course;
– Roads, Parks and Water features export, on different layers, elements pertaining to landscape.

When no data is available, you’ll be able to generate buildings at random heights (just for the LULz, I guess) between a given customizable range. That’s what the Generate Other Buildings is for, and we’ll have a couple of laughs about that later.

 

Anyways, once you have made your choices you’ll be asked to which Flux project you want to send data to, and I picked an uncleverly-named “Flux Site Project”. Once you do that, Flux will be very happy indeed.

 

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– What do I do next? –

Well, you open it in Flux, of course.

The data keys you’ll find there are corresponding to the set of datas you chose to export from the Site Extractor and that’s easy enough, right?

In the Data tab you’ll be able to get a preview of what you actually exported, and let me show what I got.

Aside from the water thing, which is like a hundread years old, everything seems rather accurate.
Well, almost everything.

If you drag one set of data on top of the other, you’ll also be able to get a superposition of the different sets.

It’s a blast. You couldn’t do anything like this before, or at least you couldn’t with such a small effort and the same degree of accuracy. I might actually cry.

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– How do I get it into Revit? –

Well, this is where it gets less pretty.
The Site Extractor is still a Demo and they are doing a wonderful job in developing it, but still the preferred channel of implementation is SketchUp. We Revit guys and gals are very much loved and considered but still have to play a little around in order to get our buildings into our preferred software. In this case I did almost everything via Dynamo and I’m sure there’s a better way, so I’m open to each and every remark.

1. I created a new project, ’cause I find that existing conditions are always best if modeled in a linked file.
2. I opened Dynamo.

And that’s easy enough.

Now, you might remember how the Flux Dynamo nodes work. If you don’t, I’ll do a brief recap.

1. log-in into Flux;
2. drop a “Flux Projects” node;
3. connect it to a “Select from List” node (and select your project);
4. drop a “Data Keys” node and connect to the previous one;
5. connect it to another “Select from List” node (and select the daya key”).

Now, I choose the “Buildings (accurate heights)” data set. You might not have anything in it, therefore you might be forced to go for the “randomized heights” data set. You do remember, don’t you? It’s the one that generated buildings at random between a height of 10 and 20 meters.
Anyway, lucky or not, what you’ll get is a mesh.

Use a Watch node to verify it, if you don’t believe me.

Therefore, I used the DirectShape.ByMesh node to throw elements from the Geometry Array into Revit.
Not that I’m a particular fan of the Direct Shape set of functions: it just was the fastest way. Still, pressing the “Run” botton might take a while.

Should you want a step-by-step walkthrough, I suggest you read this. It features an expensive car.

Now, this is where things get less pretty.
First of all, meshes in Revit suck. Like a lot.

Should you wish to use the Building Profiles data set and extrude from those your own masses, I have another bad news for you.

Yeah, that’s right.

 

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– What do I do now? –

Well, you have a couple of options.
The easier one is to use the data you just got as a basis and remodel your stuff.
There’s also a couple of very nerdy alternatives. Hold on: it’s going to get bumpy.

1. Via SketchUp.
Yeah, you heard me right.
If you use Flux to throw those lines into SketchUp, you can export a dwg and BAM, you can explode everything, transform lines into closed polycurves, then surfaces and easy peasy extrude your buildings.

2. Via a more complicated Dynamo
You have your meshes, right? Right. You can extract meshes vertexes by coordinates, right? Right. Well, you should be able to use them, and their z value, in order to recreate a more polished native geometry for your context.
If you have troubles with meshes I suggest you read this. It features a bunny.

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– What was that about random and accurate heights? –

Oh, you remembered. This is going to be fun.
Have you noticed it mention heights, but not shapes?
I didn’t notice it at first, but then I did when I saw Milan’s cathedral looking like this, when I got into the “accurate heights” set of data.

Should you not know, Milan’s cathedral looks like this.

I wasn’t sure it totally depended on the system, so I did a small test.

I went here and extracted data from that site.

This is what I got.

Therefore the morale is: keep calm, trust nobody and, as usual, always rely on your BIM coordinator.