Led by Professor Marcus White, this project saw the Urban Design Architecture team undertake solar preservation modelling for the entire City of Melbourne in order to identify public open spaces in need of protection from overshadowing.  

Aggregate shadow maps were created to simultaneously render the multiple shadow positions cast by buildings depending on location and time of day.

Using cutting-edge technology to protect public spaces from overshadowing

Rapid population increase has placed significant pressure on open public space use in Melbourne. Hyperdense, high-rise residential environments heavily rely on nearby public space for recreation and outdoor sunlight due to limited private open space amenity. Adequate sun exposure is not only crucial to population health but also essential to a healthy, sustainable, biodiverse, high-density city. 

In a world-first, we produced a new urban building envelope control assessment and decision support system using Prof Marcus White’s scripted multi-shadow casting technology applied to detailed 3D geospatial data over the whole City of Melbourne municipality: 

  • The multi-sun composite shadows are clearly expressing the amount of daylight hitting each surface over the day for different days of the year, allowing identification of open spaces in need of protection. 
  • The aggregate shadow maps we produced using powerful multi-sun solar analysis technique were developed with simple scripting to set up multiple sun positions with linked parameters for location and day of year, which renders multiple shadow positions simultaneously.  
  • The cutting-edge GPU rendering implemented on this highly detailed interactive Para-Shadow model is significantly faster than traditional CPU rendering offering the opportunity for a single urban designer to receive rapid 3D visual feedback on different urban proposals. 

These multi-sun shadows maps can be rendered as black shadow fans or can be combined with post-processing exposure control render setting, to set a colour spectrum range to clearly express the amount of daylight hitting each surface over the course of a full day and over different days of the year to help access overshadowing of existing public open spaces. 

Additionally, the solar carving analysis was driven by the sun-carving modelling technique ‘the Subtracto-Sun’ created by White, which uses parametric solar systems and realtime parametric Boolean operations. The tool creates a permissible building envelope by subtracting a solid negative ‘shadow’ object derived from angles of the sun during the given period. This results in the development envelope within which any building can be built without casting a shadow onto the public open space (e.g. plaza or park) within the designated times. 

This colour spectrum range expresses the amount of daylight hitting each surface over the course of a full day (and over different days of the year).

The outcome: a world-first urban building envelope control assessment and decision support system 

The research identified the key public open spaces in need of protection, developed maximum heights restriction to protect sunlight access to parks. The City of Melbourne has adopted the research outcome and prepared the Amendment C278 Sunlight to Public Parks to the Melbourne Planning Scheme. This amendment is the only review of the Sunlight to Public Space Local Policy since 1999.  

This is the first time in Australia (and the world to our knowledge), that this scale of solar modelling has been undertaken to inform planning policy.  

The approach and process of this research is widely applicable in other cities to evaluate the existing conditions and planning schemes, offer practical suggestions with comprehensive and intuitive research data to public and councils, give policymakers and planners a more accurate understanding of development opportunities and restrictions. 

For more detail please refer to the City of Melbourne Website.

You can also try the interactive shadow map

Project timeframe 


Research team 

Shadows by time of day were mapped across the entire City of Melbourne.

See more projects from the Urban Design Architecture program

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