Altitude and Reference Levels for Singapore BIM Submission

[Vimal Kumar]

Note: This article was originally published on AsiaBIM and was written for Archicad 19 mainly for architects working on the Singaporean market.

Setting up the Project Altitude properly and displaying its values for BIM Submission in Singapore requires a bit of insight of the Reference Levels function of Archicad which the local practice might not be fully aware of.

As a default, the location settings have 15.00 metres set for the altitude in the architectural BIM Submission Template of Singapore. Yet, when opening a Section or Elevation, it shows 115.000 – as required for submissions.

Upon checking the settings of those said viewpoints, the Reference Level option under the Story Levels panel shows False Datum (Survey), which ensures the conversion of 15 metres to 115 metres.

When changing the Altitude under Options/Project Preferences/Project Location to
i.e. 18.50 (metres), the Sections/Elevations will not update until we update the Reference Levels as well.

1.,  Go to Options/Project Preferences/Reference Levels.

By default the marker symbol under Relative to is next to Project Zero. This marker is only valid in this setting dialog and is only relativizing the definition of the values to each other.

2., Since the False Datum (Survey) should always be below the Sea Level by 100 metres, first we need place the marker next to Sea Level (1.), then change the Elevation value to -100000 mm (2.) (as per the modeling units).

Now all settings where the False Datum (Survey) is set as a to-be-displayed value will be updated.

Everytime, the Altitude values change, the Reference Levels need to be checked also.
The reason of simply not setting the Altitude to 115.000 and 118.500 metres respectively in the example above is to separate the ‘real’ elevation above sea level and the theoretical False Datum, which is represented in the displayed value of the elevation of spot levels of the Singaporean land surveys.
If there is no model exchange with overseas consultants then the Altitude can include the additional 100 metres directly and the False Datum (Survey) as a Reference Level needs to be changed to Sea Level.