Wednesday, 14 May 2014

At Siscín we often work on multi-discipline. In    
these projects numerous softwares can be used
such as Civil 3D, Bentley  MX Road/Rail.,
AutoCAD , MicroStation, Revit, 3DS Max etc.
We are often involved in the coordination,
 training, modelling, visualisation or all of the

The project starts off with the civil/survey data From the Civil/Survey data we get our site, our  levels and we can create our DTM (Digital Terrain model).

If we are using Revit we will use the survey data to derive our shared coordinates. When it comes to coordinates Revit differs from the other software’s. The other software’s mentioned above all work in world or absolute coordinates based on 0,0.  Revit works differently. In Revit your coordinates are relative and your site can not be further then 33km from the origin. Origin is probably a bad word to use, in Revit we call our reference point (origin) the project base point.  When it comes to positioning your project in Revit a lot of people have a mental block. But it is very important that your project is positioned correctly if you want to use setout coordinates, analysis or if you want to collaborate with users using other products.. In today’s blog I won’t go into setting up shared coordinates. I will deal with this in a later blog. But if you want to learn about it now, go online and search for Revit and shared coordinates. If  you are using Revit in your project you will need to pick a reference point on your survey and this will become your survey point or you project base point.

In the last blog I mention the BIM Execution plan. The coordinates of this reference point should be outlined in this document. Not only do you need it for Revit, you will need it to ensure all your models are coordinating correctly. If you are using 3DS Max for visualisations, sight or lighting analysys you will need a reference point because  Max does not use absolute coordinates either.. I will discuss more about positioning your model in 3DS Max in a later blog.

When you have a number of software’s involved in a project good coordination is critical. For example if we take a road or a rail project. These projects can include roads, building, drainage, ducting, electrical systems and many more. You could end up using all of the softwares mention above and more. Careful planning from the start of your project can make the coordination less complicated.

As you have probably gathered from this blog and my last one. Planning and good BIM management at the start of a BIM project is essential. Followed on throughout the project with further management and coordination. A BIM manager or coordinator is must have on any BIM team.

If you have any questions on anything in this blog or any other blog please feel free to contact me at

Dan Deery is a director of Siscín which is a company based in Ireland specialising in BIM Consultancy, 3D modelling and Visualisation. Siscín have worked on many different projects across the world. For more info on Siscín and their services check out their web site on

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