Zoning Clearance Thoughts

A long time fellow Revit traveler reached out to me via Revit Lifeline last night asking about zoning clearance ideas. Where he lives and works they want designers to demonstrate the building is not too tall. They also want them to prove it doesn't extend into a zone that leans back into the site. All in all the code reduces the size of the building that can be built on any given property that falls under its jurisdiction.

I have heard and read about this concern many times over the years. But in response last night, I mocked up a quick example to see if it met his needs (waiting to hear back). I thought, "Blog post? I just posted something the other day...don't get carried away. Yeah, but you've only posted like twice this year slacker! So a blog post it is then..."

Here's a few images to ponder first. Pretty fancy house design eh? Doors and windows are so last century. I CAN design YOUR next home, just call when you're ready...operators are standing by.

The upper surface is a thin floor which is manipulated through Dynamo and Shape Editing. Lauren Schmidt's LandArchBIM blog is a very nice source for land techniques and I stole her graph ideas in this post to make it. Her post explains the technique relies on a sub-region to match whatever hardscape shape (property boundary in this case) is necessary. I used the floor's offset parameter to move it up above the surface by the zoning height required.

The front and back property boundary clearance requirement is built with a railing and profile. The fact that railings can be hosted by toposurface now opens this door wide. The surface form might not lend itself to a nice clean railing though, mileage will vary. You can see the rear railing is a little deformed in a couple spots. I built parameters into the profile so I could (using types) vary the height of the angle portion, change the angle, change the height above property (spring point of the lean) and the thickness of the railing.

I created a specific material to assign to it all so it can be mostly transparent.

My example is admittedly simplistic. How many property boundaries are really a simple rectangle? Pretty rare, about as rare as a purple unicorn that uses Revit? A front or rear boundary that has arcs and many segments will probably pose some issues creating a hosted railing. I can imagine things going wrong but I'll wait until I'm dealing with something specific to worry about that.

The file I mocked this up is in Revit 2020.2 and the dynamo graph (link has both RVT and Graph) is so simple that this screen shot would help you build it nearly a fast as downloading and opening it up. That's what I did with Lauren's example. You do need the packages I've circled.

Oh, the mockup has a massing element too, you'll have to turn massing on though. At first I thought I'd sweep a profile along the property edge defined by the upper surface. After I did that I thought of the railing. The learning curve is much less steep for a railing than massing, bonus being much faster too.

Decided to add a couple more images. I realized that I could have turned off the sub-category Interior Edges for Floors to hide the tessellation in the other images. It also occurred to me that another railing and profile configuration could deal with the top. I just created another type from my existing profile family to make it a 90 degree railing. A separate wide profile without a vertical portion would provide just a top surface. The floor and railing approach don't result in the same surfaces but within reason? If reason can be applied to a zoning requirement?

Here's both visible...

Toposurface from a Text File

I responded to a thread at the Autodesk Community Revit Forums back in May. They described having a survey file and a points file that could be used to create a toposurface. My initial reply focused on resolving this warning, "Imported Toposurface Points are located a large distance from the model and might not display properly. Points will be centered on the model instead".

I offered this advice.

• Import the survey (a DWG file) first using Auto - Center to Center
• Move it so the relevant portion of the site is roughly centered on the Project Base Point/Survey Point
• Select the Survey Point and Unclip it (this prevents it from moving to the 0,0,0 location of the DWG file in the next step, which is far away)
• Acquire Coordinates from the DWG survey file

This resolves the real world coordinates based on the survey data. I felt they'd be able to create the toposurface successfully. Instead, they responded that the toposurface was not created in the correct location. I took another look and experimented with the points file they posted (in the thread) and offered these steps.

• Add a new set of point coordinates to your text file at 0,0,0, on the first line.
• Use this version of the points file to create the surface.

I then commented, "If you followed my directions earlier about acquiring coordinates you should see the coordinate values of the survey file when you select the Survey Point.". Then I recommended the following steps.

• Unclip the Survey Point > Enter E/W: 0' and N/S: 0'
• The Survey Point should jump to the 0,0,0 location of the survey file, far from the project origin.
• Make sure your View Range is set high enough to see all the points of the surface
• Now create your toposurface
• When the points are visible you'll see one point at 0,0,0 but it will be at the Internal Origin (>R2020, Project Base Point in older versions)
• Select all the (toposurface) points > move using the Internal Origin/Project Base Point location as your first pick and the Survey Point as your second pick (see image below).
• This will move all the points down so the toposurface is located properly relative to the survey
• Before finishing the surface > Delete the one toposurface point at 0,0,0
• Finish Surface

I found that adding the extra point at 0,0,0 silences the warning about the distance from origin and it gives us a known location within the point data to select and move the entire surface accurately.

Then another member asked about doing something similar but wanted to report a project elevation of 100'-0" instead of 0'-0". I replied with the following.

In order to show the Project Elevation as 100'-0" you'll need to model your building at that project elevation instead of 0'-0". Then when you establish shared coordinates you can show the true elevation. If I was tackling this I'd create a building model at 100' and a separate "site" model.

I'd import the site data in the site model and create a toposurface. It should be at the real elevation and report the relevant coordinates you expect. Then I'd import the building into the site model, move it into position X/Y, rotate it if necessary into alignment with the site conditions and finally move it up to the intended ground floor elevation. Then I'd use Publish Coordinates to pass the building position information out to the building file.

When you open the building model you can edit the Level parameter Elevation Base to use Survey Point (versus Project Base Point) and it will show the True site elevation values instead.

Just a couple days in the life of a thread at an online user forum (spanning nine months).

Five Minutes with a Toposurface

I created a video to describe what happens when Revit contours don't quite match up with the underlying cad file contours that were used to generate a toposurface. The first part of the video explains that the Site Settings usually don't match the contour interval settings of the cad source file. Changing these settings is often enough.

When we want Revit to provide more contours than the source file provides it can but that's where we start getting some distortion of the contour lines we see. The rest of the video shows how to manipulate the contour lines with additional points to help Revit sort it all out.

Keep in mind that Revit creates triangles between points. You can see these if you use Visibility/Graphics to turn them on.

This is what the triangulation looks like before adding an extra point to help Revit draw the contour more accurately.

This is what the triangulation looks like after adding the extra point.

Here's the video embedded or watch it at OpEd Videos or You Tube instead.

Dept. of Bugs - Sloping Pad Defect gets Ornery

I wrote about THIS back in August of 2009. The sliver left behind in the image below could be eliminated by taking the advice in that post. Unfortunately 2011 eliminates that technique from the ranks of viable alternatives, per Jean-Frederic Monod's comment on the earlier post.

Possible workaround? Use a pad to drop the site toposurface to the lowest elevation and then use a floor to create the sloped and flat "pads" instead??

Pads and Slope Arrows

I received a question the other day about an unwanted sliver of a toposurface element appearing. At first the assumption was related to Design Options because there was quite a bit going on. Turns out adjusting the pad and its Slope Arrow could resolve the issue. Here's a picture of Pad A and B. Pad "B" obviously has the sliver problem.



Pad A is two pads, one flat and one sloping. Both pads are set at their lowest elevation and the Slope Arrow tells the pad to go UP. Here are the properties of the sloping pad.


And here are the properties of the Slope Arrow for A.


Pad B is also two pads but they are defined a little differently.


Pad B's Slope Arrow properties.


When you need a pad to slope it seems that it is more reliable to define the lowest elevation and work up than in the reverse. At least it helped resolve this sliver.

Site Toposurface - Graded Region - Net Cut Fill

While attending a Revit Structure user group in San Diego (last week), my first chance to visit finally, Behzad was demonstrating some of the new extensions, the Bridge Extensions content available via your Subscription account at Autodesk.

He showed something that, on the surface (pun intended), doesn't dawn on most users. The graded region tool isn't the only way to get your Net Cut/Fill results. This is true because Revit really only cares that one surface is existing and another is in a future phase. In other words you can model one surface in an earlier phase and model another one in a later phase and the properties of the newer surface will show the net/cut/fill values compared with the earlier surface.

One condition: New surface must not be created outside the boundary of the earlier surface. If it is...it won't compare them, no cut/fill result.