With a wide range of survey deliverables, we often experience client's misinterpreting what a 3D deliverable is. For example, you might automatically think of 3D Revit models or SketchUp models when you think of a 3D deliverable, but this is not always the case. We spoke to Gary McIntosh, SUMO's resident Measured Building Survey Manager to get his thoughts on what is a 3D deliverable…
So, Gary, can you tell us a bit more about 3D deliverables?
We have a wide range of deliverables available to clients, and as mentioned previously, frequently people may expect a deliverable that gives them a full 'visualisation' of their site such as a Revit model. But there are various deliverables that we can offer based on a client's time and budget requirements. This includes:
3D Topographical Survey and 3D Utility Survey drawings
3D topographical survey and 3D utility survey deliverables contain the raw data collected during the survey which has been exported and presented as 3D ‘points' and live work.
Above left: 3D topographic survey deliverable from a birds-eye view. Above right: 3D topographic survey deliverable from a 3D perspective view.
The image above left shows a 3D topographic survey from a birds-eye view. The picture above right is a snapshot taken from a '3D' perspective view. The lines at the lower level of the perspective view present in this way because these points were taken using a reflectorless (laser) method of measurement (as the surveyors could not collect a true measure of the Z-axis, possibly due to access restrictions). Because these points had no Z-axis value when captured by the surveyor on-site, they automatically present with a 0.00 level when exported into the AutoCAD software. Therefore they look 'lower' when in a perspective view. The other data points were captured using what we call 'true values' or 'true measurements'. This is where the surveyor has directly measured the points. Thus, the data points present themselves correctly on the Z-axis when exported and shown in a 3D perspective view.
What does this mean for clients in practice?
When commissioning 3D topographic surveys, our clients must consider areas which cannot be accessed by foot or have restricted access. This is because areas where a true measurement of the Z-axis can't be determined, will not present correctly within the 3D file. SUMO will always work with clients to ensure that restricted access areas are clear and ready for the surveyor to capture.
3D AutoCAD (wire-frame) Models
3D AutoCAD models are commissioned more infrequently. This is because (as in the images shown below) the survey deliverable is presented as a wire-frame model (left image). These deliverables are produced using X, Y, Z data coordinates and additional information, such as extra Z-axis values. SUMO's 2D survey drawings contain the same measurement information as 3D models. But they are presented in a 2D format to meet the client's requirements. Therefore, the 2D drawings should contain all the information a surveyor needs to produce a 3D wire-frame model.
Above: 3D AutoCAD (wire-frame) Model
The example images below show a basic wire-frame model. Each area of the building surveyed contains the shape of the room and the floor levels. This gives us our base X, Y, Z shape. SUMO also includes the height of the room on our drawings (additional Z-axis value) which allows us to create a 3D box as laid out in the images below.
3D SketchUp Models
Between a 3D AutoCAD wire-frame model and a full Revit model, we have SketchUp. SketchUp models are produced using laser scan pointcloud data or from traditional measurements. SketchUp models are an excellent method of visualisation and can be presented as 3D images as well as 2D files and as animations. They provide a fast and cost-effective way to work in and view buildings in a 3D format.
3D Revit (BIM)
Revit Toposurface:
A toposurface is the 3D Topographical survey taken into Revit and modeled. This is shown in the image below. The toposurface is the basic lay of the land, but while being a 3D deliverable, it does not present as a 'model'.
Above: Example of Revit Toposurface.
Basic external Revit Model:
A basic, external Revit model includes the toposurface (discussed above) with surrounding buildings shown as mass objects (see the example below).
Above: Example of an external, basic Revit Model.
Detailed external Revit Model:
Depending on the level of detail required, a detailed Revit model may include all the kerbs, footpaths, raised areas shown with full geometry, lampposts, bins and trees shown as objects. The building details may consist of the windows, doors, roof, chimneys and more.
The range of options for Revit As-Built survey models is wide and varied and customisable to suit your project needs. To also simplify the specification, SUMO has three typical levels of model that are suitable for most situations. We have created the SUMO BIM Model Specifier which outlines these three typical levels of model. You can view the BIM Model Specifier below:
And finally, 3D deliverables can also be used for underground models: -
Revit Utility Model
As shown in the image below, a Revit utility model is a 3D representation of the underground infrastructure. Unlike the 3D AutoCAD wire-frame models (discussed above), which present a series of ‘lines’ to make up the wire-frame, the Revit utility model shows the underground infrastructure. This includes pipes and cables in relationship to the chambers accessed from above ground.
