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Review

Revit - The Parametric Building Modeller

From CAD User Mechanical Magazine Vol 13 No 10 - NOVEMBER 2000

In this particular article we’re going to look at the various forms of Spline based modelling (a spline being a series of vertexes and segments making up a 2D shape) a technique available to you in both VIZ and MAX.

It seems that since the onset of Autumn it's become an "open season" for the AEC software developers, new versions of all of the leading building CAD systems are just over the horizon, Architectural Desktop 3 and ArchiCAD 7 are beckoning…there are also several systems well known in Europe such as AllPlan, who are also making serious bids for UK business. A new player in the UK market is Revit Technology Corporation, who had a major stand at the recent AEC systems show in Olympia. You might ask yourselves is there room for yet another system, and what can a Revit have to offer that the others haven't already done and done well? Revit professes to be the AEC industries "first parametric modeller". Do they say this in jest or just to get a response from some of their leading competitors. Certainly parametric's is not a new concept, and it's a known and accepted technology in MCAD applications. At first glance Revit certainly does not have it origins in 2D drafting or any typical CAD programmes. It forces, or rather, introduces you to use the SBM "single building model" concept from the outset. The SBM is not a new idea and has been tried several times before with limited success. For any new software to succeed it has to have an intuitive and easy interface to pick up without getting bogged down in the complexities command lines, code and "workarounds". It needs to work the way architects and building engineers would do. In other words, get on with working out the building plan without the bind of understanding what the software is doing - or not doing in some cases. In this review we'll try and give you an idea of how the various elements of the package work, and look to see if the promised 100-day development cycle can deliver specific AEC solutions for the built environment. The first area we'll concentrate on is the user interface:

Interface
Revit has a similar feel to NavisWorks in many ways as it has a clean and easy interface to pick up on to the point of being unassuming, and does not require any pre-knowledge of any particular CAD or AEC software package. In fact after 2 to 3 days of using the software you could teach it to a non-CAD user or non-architectural person, without many headaches As with most of the Windows based programmes you have the usual File, Edit and Help pull down menu's, and a second menu toolbar for Cut, Copy, Zoom and 3D etc. The remainder of the interface is then divided into three areas:

l Design Bar with rollout functions covering Modelling (for most of your typical AEC and project based functions), Massing (for those feasibility studies), Documentation (schedules, text and drawing set-up), Detailing, and Edit.

l Project Browser browser is similar in essence to an explorer type tree structure, allowing you to display all of the current, views, schedules, sheets and families active in the current project.

There are no other floating or hidden toolbar functions other than the controls and properties of the building components that can get in the way of getting on with the model. To start a project you could either begin with the Massing functions, which seems to be a popular element of many AEC packages today, where you can quickly draw out outline building shapes and extrude them to size, move large elements and blend them together These can then be easily converted into walls and structural elements and, as Revit works with the "concept" of the building model in mind, it has already set up for you some predefined elevational views and levels. So pretty much as soon as you've started creating the mass model you could switch to one of the elevational or plan views (pic 05). From then on it’s just a case of changing from the mass model to a shell where you can change the wall styles, begin to add doors and windows etc. (pic 06) But for most of us the starting point will not always be the mass study. The beginnings of a project might be a space planning exercise, roughly tracing out the building shape, getting room sizes right, then seeing how it works in elevation, ..."oops" now we've got to make some changes…This is where the parametrics at the heart of Revit really come into play. In any developing building you will up, until the time it gets built, be for ever changing and amending various parts of the design, detailing and specification. In Revit you can do this in "real time". Any changes at plan level update the model as a whole and are reflected in the elevations, 3D views and sections. The process can also be extended out to the documentation side, where changes made to door schedules, room schedules, size amendments are fed back into the model. This will certainly take the chore out of going through the entire set of plans amending each door in turn. The same can be applied to windows, M&E components, rooms and fixtures and fittings. The schedule element of Revit alone is worth having serious look at, as it delves into FM applications area and has the inklings of being an excellent information source.

Building solutions
The next area to concentrate on is one we'll all be familiar with, that of getting a building into some sort of shape, organised into the various floor plans and elevations. So, how easy is it to start drawings walls. Well, as we hinted at, earlier in the article, you do not require any pre-knowledge of CAD systems. After clicking on the wall button, in either the Basic or Modelling functions, you are given a choice of wall type, its properties (this can also be the route for adding new wall types), the level (storey) you are working on, what level the wall is being extended up to, and a series of, what I would call, drawing helpers, i.e. whether the wall you are drawing is a continuous wall, arcs, tangents or fillets. The walls can be drawn following a centre line, on near or far faces, or offset from a centre line. As can be seen from the illustration, you can draw any shape of wall and curvature without the programme going into terminal meltdown. As you begin the process of drawing walls you are given direct information on its’ length, angle relative to elements adjacent to it, the dimensions and offsets being added from the keyboard at the time of drawing or simply click on the wall following its creation, and a whole host of dimensional information will be available to you to use. Or amended as you see fit. Various wall elements, as they're added, can also be locked together, or locked in place, thus preventing you from any un-wanted accidental revisions. Similarly the dimension process has added benefits. You can dimension elements and then lock them to walls. If you move the wall the door or window goes with it, and you are also alerted if you are try to break constraints set between various elements.

After creating the basic walls and building shape, you are free to carry on the modelling/ design process in any one of the elevational, sectional of 3D views. If you find it easier to populate the new elevations with windows and doors you can do so. Flick back to one of the plan views and the changes will have been made.

Project management
Once you've committed yourself to a project you need to be able to navigate your way around without reverting to, or delving into, other directories to get plans or elevations that relate to your model. Revit is similar to ArchiCAD in this sense, where you can move within the single environment between elevations, sections and plans. The level or storey tags have inbuilt links to the plans. Double click on the tag and the plan window is brought up for you to work on. You are not barred form working in any specific view. If you feel the need to work in the 3D view, then it’s relatively easy. Setting up forms and schedules is also a painless operation. If you need to gather information on room areas, function etc. simply drop a room tag from the Modelling rollout into an area, and set-up a schedule from the Documentation menu. You have a choice of eight different room components, area, finishes, department etc. Select which ones you need and the new schedule will automatically pick up on the room tags in the model. Needless to say, if you add more rooms to the model the schedule is updated. Likewise, change a name in the schedule, and the model is updated.

Adding in further views, sections and levels is also made very user friendly. If you add a further level into the model, you can select all or part of the walls and tell them what level to extend up to - this could be the roof, the next level up or sub levels. It's all beginning to sound too good to be true. In truth, you can get very far with your design work very quickly. It's then that you realise that you need to learn more about the programme, before you can call yourself a fully accredited - "Reviteer…". Their term, not ours.

Documentation and Training
What no manuals, yes this has got to be the smallest Manual set we've ever seen with any programme, just a 44 page "getting started with Revit", no huge manual set to burden you shelves with, it does however have a very good online help system, QuickTime movies, and a reasonably extensive Training section, covering most of the basics, plus the functions new to 2.01. Revit's web site also has a good set of tutorials and guides, which you can have e-mailed to you on a regular basis via the Revit Newsletter. So getting started is not too much of a problem. Technical help and assistance is also free via the subscription programme, your £165.00 per month covers you for any queries and problems that may arise.

Move to Revit?
Is there sufficient depth in Revit to abandon some of the 2D packages and consider putting your AutoCAD AEC or ADT to one side? If you believe some of the press releases you have to at least consider Revit as a viable alternative. It does lack some depth in some features that others have had time to build up on, also the UK flavouring could do with some work. UK flavouring has been a problem with other AEC systems, ADT having the same criticisms when it was first released. Revit have committed themselves to a 100 day development cycle that is set to pick up on some of the weaker areas and expand in others, they are also hinting at developing further ties with third party developers, Accurender being used for the rendering and materials in this release pic 11, 12 & 13, and it would benefit from having this expanded further so that you can export the final image files and or carry out panoramic QuickTime or SmoothView renderings. The ease of use or Revit will no doubt warm to most sceptics. It will no doubt suffer the same criticisms as ArchiCAD has, that it's too 3D and not enough 2D content, how do you draw details? And annotate etc. Revit does not purport to being a draughting package, you can add detail to "call-out" views, you can also link in DWG and DXF files, making use of the wealth of manufacturers details, so the 2D argument wears a little thin. If you're considering a move from a 2D architectural system to 3D and all that that move brings with it then Revit is certainly one of the easiest programmes to learn.

In summary
What are the hidden costs? unlike its contenders Revit works on a monthly subscription, initially you pay £165.00 per licence, this rate is variable depending on the numbers involved and Revit are best to advise on that. You then continue to pay £165.00 per month, which includes updates, feature releases and training.

If you have three or more seats then you can also enrol on the "early adopter" scheme that involves you in adding to and contributing to the new content and features in future releases. So over a year the total package will cost you £1980.00, however the interesting part is that if you do not want to have a monthly subscription and say you only want an upgrade when there's a major release then you only have to pay a further £165.00 as and when you require the update, an ideal situation for the smaller practice or office. Can Revit overtake the likes of ADT and ArchiCAD or take on highbrow systems like Microstation TriForma, well as usual only time will tell, it has a great deal of potential and its fun to use if that's an appropriate term, it also has some serious financial backing, so expect to hear more from Revit in the New Year. CU
For more information visit: www.uk.revit.com

Review

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