Since we presented about the showcase to the CityGML Standard Working Group, we’ve divided the 2.4GB data archive provided to us by the SITG and prepared individual archives for each domain. These are now hosted on the Showcase portal. After agreeing to the terms of use, each developer must download and examine the files locally and separately.
Determining which data set to use and how to merge (mash up) data sets is time consuming and requires analytical skills that most application developers do not have. The Showcase offers an opportunity to explore different strategies to overcome this obstacle. We have been discussing the options with CityGML SWG co-chairs Steve Smyth, Carsten Rönsdorf and others.
One question is why the data sets exist as separated files. In the city of Geneva, as in almost all city GIS departments, creation and maintenance of different data sets are the responsibilities of different agencies or departments with expertise in each domain. The data's maintenance is a cost center that needs to be attributable to specific budgets and uses drive the selection of formats in which the data are provided. That said, independent data sets have to be coerced into working happily and seamlessly together when developing a multi-disciplinary application.
Wouldn’t it be valuable for the datasets could be viewed/accessed right from a server in a continuous model and to see where and how they overlap? We had a discussion about the use of CityGML for this purpose. "Determining fitness for purpose and the type and amount of work needed to fit them together is really hard without using actual samples" notes Carsten Rosendorf.
Carsten suggests that if the data could be conflated into one CityGML model for everybody to use, it would be a great start. It might be possible that the developers would be able or would need to do this (conflate data, not necessarily into a CityGML model) prior to developing their applications.
The 3DGVA can help the developer and data publisher communities better understand these issues. Now all that is needed is the team to conflate these data sets into a CityGML model of Geneva. Is that your calling? If so, please raise your hand!