Point cloud file formats vary in terms of data structure and complexity with different software platforms. It is critical to set the scope and expectations clearly when initially engaging your surveyor ensuring that all parties are aligned and minimising risks of compatibility issues or potential reworks.

We strongly suggest communicating the below factors.

Extent
Defining the areas to be scanned helps avoid unnecessary data collection, reduces processing time, and ensures that only relevant information is captured. This also ensures that the surveyor is aware of the scan’s intended purpose. This could include:

• Typical survey Including site boundary and visible neighbouring properties.

• Targeted survey limited to specific areas i.e. heritage facades, critical vegetation.

Format
Pointcloud files come in a number of varying formats (such as LAZ, E57, PLY, XYZ, PTX) which serve their own individual purposes. ArchiCAD is best designed to handle E57 and XYZ formats offering their own integrated workflows. It is best to communicate this format preference to the surveyor so that your expectations are aligned.

That being said, ArchiCAD is generally not suited to processing point cloud files and will struggle with files larger than 100mb (3 million points). To ensure a smooth working experience, we recommend limiting the file to 50mb (1.5 million points).

Further to this, point cloud files, whilst impressive in its level of detail, is generally impractical for architects, requiring a level of tracing/modelling to make use of the data. This comes with a level of risk which is best avoided. Like traditional building surveys, pointcloud files should only be supplementary to a set of CAD drawings with relevant annotations such as levels and dimensions.

Note > The maximum point cloud file size ArchiCAD allows to process is 4GB. 

Complexity
Pointcloud files and 3D scanning processes are able to capture substantial amounts of data. We found that more often than not, this resulted in an excessive number of points. This can lead to additional processing time required to trim unnecessary data from the file.

To avoid this as much as possible, it is best to communicate the need for various sampling rates to suit its intended use. This should be discussed prior to start of works.

Fine Detail
Detailed areas such as, complex facades, ornamental elements (filigree balustrades, detailed masonry etc) should be sampled at a higher rate to capture key details.We suggest a 10-50mm point spread.

This allows the surveyor some flexibility to adjust the spread to capture critical/complex geometries as necessary. Generally, a 50mm point spread is appropriate for most applications.

Moderate Detail
Larger areas such as civil works or basic massing can be sampled at a lower density. A 100-200mm point spread will capture a lot of details whilst keeping the file size light.

However, it is still crucial to consider key details such as kerbs, drains and other elements which may not be captured corrected with a higher point spread.

 

Low Detail
Large terrain and topographic works to be sampled at 500 – 1000mm point spread. Specific areas of interest such as exposed services might require higher density scanning.Example: Point spacing difference between detailed facades and roads. Sample images of bothEarly communication of your survey requirements will assist in avoiding unruly files and future reworks.