Monday, August 21, 2006

Mathmatical Forumlas in Families

This post actually comes from my friend David who orginally posted it on AUGI. Since I can never keep track of items in forums I decided to repost it here. Enjoy.


Not a math genius, or even a Revit one (or else I would have spent way less time figuring this out) but I think I have a way to deal with the "Inconsistent Units" error message. I had a problem in which I needed to calculate the arc lengths of some segments. I used a slightly different method (from previous posters, Ed), but the critical piece (the "Inconsistent Units" error) was the same. In the end I realized that Revit, just like my Chemistry teacher, expects me to cancel units in my equations. Even though WE know that the units cancel out (and that Pi is unit-less) Revit is quite literal: Pi is a number, arc length is an angle, radius is a Length and so on. It cannot see how you could possibly relate them with mathematics.

As you realized, you can trick Revit in a couple of ways, I am attaching a screen shot of two examples. In the first (Green Arrow) I added incorrect units to values. You can see this makes the equation "work" but yields an answer in degrees whilst we want feet and inches. The second way, (red Arrow) is to break up your equations so that portions of them yield "unit less" values, and then combine them at will. Of course you could get this functionality in a single equation, so long as your units all cancel to yield whatever parameter type you are supposed to have.

Wednesday, August 16, 2006


This will be a short post... Not enough time in one day to get everything done.

We are excited by the prospect that the new keynoting feature that Revit 9 brings to the table, however we are quickly realizing that in a firm of 600 employees it presents certain problems that one might not typically run into in a smaller office environment. For instance, given that we have 7 offices or so, needless to say there are a number of project managers and architects who have their own thoughts and opinion regarding how drawings should be noted and what notes should or shouldn't include. Therefore we must take the default keynote list that ships with Revit and evaluate it against what our PM's expect, and the contents of our standard outline specification.

The way keynoting works is a complete reverse from how architects have typically noted their drawings. In the past we of course drew some lines (or extruded some shapes, whichever) and the added notes later to describe what the "lines" represented. Now, with keynoting, done correctly, all the thinking needs to occur ahead of time, as the object is being modeled. Of course its possible to use more generic keynotes early on before the detailing of a building has been completely thought through (place holders as it were) (see Daniel Hughes' recent post) but needless to say this is still a new way of thinking regarding documenting a building. This is where it is important to make sure that above all else Project Mangers understand the process of BIM, even if they don't necessarily know everything about how to use a specific piece of software, BIM training.

The other opportunity that the keynote feature provides is a way to close the loop of Revit -> Especs -> Revit. Now it will be possible to model the building, extract the information from the building model to create an outline specification, have the spec writer further develop the final project specification, and then modify the keynote table to match the final specification. This shows us that for each project we need to expect to make a local copy of the BH typical keynote file, so that each project can modify it as needed per project specifics.

One last thing that keynoting now allows, 11th hour modifications to a drawing set without having to actually change the model or its geometry. For instance say you have a project where you've specified slate roof shingles, at the last moment its determined that you need to use asphalt shingles instead. In most cases you would probably want to actually change the model, but now if the shingles are keynoted, all you really need to do is modify the keynote of the roof, if for some reason you don't want to actually change the model at that time.


Tuesday, August 01, 2006

training BIM

We recently had a two day retreat where everyone involved with implementing BIM accross our U.S. offices got together to really start laying the ground work for a firm wide push to adopt the design philosphies of BIM, and therefore the use of Revit. Our CEO has already drawn the line in the sand, he expects us to be 100% BIM in 3 years, this is HUGE, the first reaction is probably one of shock, consider our market sectors for a moment, health care, higher ed, mixed use development, high end multi family residential, sci tech, k-12, and commercial/retail. That is a variety of project types and project requirements to move into a BIM mode of production. However, the second reaction should be "thats HUGE" not because of the mamoth task ahead of us, but because we have complete corporate leadership buy-in as far moving our practice to a BIM based practice. Not only that, but our CEO and other key leaders in the firm understand conceptually what it means to be practicing BIM, and why the investment in transistion to a program like Revit is worth it.

So; that is what our 2 day meeting was about, creating a full implemntation plan for our firm, what are our priorities, what do we need to do, who are we going to need to do it, how much time is it going to take. This way we can tell our leadership what we need to full fill their goals, and they can endorse it, and help to make sure it happens. One of our great advanatages we feel moving forward is that most of the people who were at our 2 day meeting are practicing architects and engineers, this train isn't being driven by IT, IT is enabling us, and supporting us, but at the end of the day the implementation and use of BIM is being pushed forward by people who are working on projects everyday!

This brings me in a round about way to my original intent of this post. In our 2 day meeting we talked about training. During that discussion we realized that in the process of moving our firm to BIM/Revit, there are two different things we need to train people on. Users need to learn how to technically use Revit, but at the same time people need to learn what BIM is. BIM is not Revit, Revit is a BIM tool, to practice the theories of BIM a user does not have to be working in Revit, they could be in sketch-up, or archicad, or excel, the point is that BIM needs to be a philosphy of practice that affects how we design, how we deliver value, how we practice our proffession. To us, it is important to clearly seperate BIM from Revit, Revit may not be here forever, but we strongly feel that BIM is where our proffession(s) have to go, we can't look back, we must press ahead!

To that end I've created a simple vignette that illustrates the concept of BIM, without using Revit! (oh and say hi! to Mrs. Robert, :) )