Using Revit Architecture 2010 with a sloping ground (created using toposurface) it does not export in the GBXML format for Ecotect.

Ecotect is a new program we have to teach in our education facility but with no users it is being learnt on the hop. For shading analysis we have buildings on different levels, how does ecotect calculate shadows allowing for sloping sites if it does not import the ground surface?

Is it something you create in ecotect and if so what tool do you use?

We modelled the shell of the surrounding buildings easy enough and imported our complex model for the proposed building in Revit and exported via GBXML but need a site to be relevant/accurate.

Thanks for any help.