3D City Models

1. This could be the most important market opportunity for 3D laser scanning.
2. The OGC and ISO have developed important database standards.
3. Berlin, Germany and Glasgow, Scotland are excellent examples.

I have a variety of thoughts on this subject – probably more than one post, but let’s see where it goes. There is a lot of R&D, excitement and in some cases, hype, going into 3D city modeling, in the US and around the world.

From a standards point of view , the good news is the OGC – Open GIS Consortium has created CityGML – City Geographic Markup Language as an open standard for the representation, storage and exchange of virtual 3D city and landscape models. There is also a related ISO standard. A separate CityGML organization has also been formed to promote the cause. These references are important foundation elements to becoming a player in this space.

It is also important to recognize from the start that laser scanning does not have a monopoly on building “geovirtual” 3D city environments, in fact it may not even be the preferred, i.e. most cost effective methodology, depending on the intended use of the model.  Aerial photography, particularly oblique can offer real value when it comes to automating the development of a simplified database.

Perhaps one of the most advanced models is at the City of Berlin, Germany. Work began on this project in 2003. As mentioned in a previous post the City of Glasgow, Scotland model was developed using static laser scanning in combination with photography and a significant 3D modeling effort led by Doug Pritchard. This model was justified in large part to preserve the historical character of the downtown.

Back to the CityGML standard, one of the key concepts to investigate and understand is the Levels of Detail (LOD). This is where it gets more interesting. At LOD0 you have essentially a 2.5 D DTM with a draped image.

At LOD3 (image on the right) and LOD 4 is where I think it gets interesting. This is where one begins to see the potential convergence/intersection of BIM (Building Information Modeling), GIS and 3D laser scanning. At these levels of detail the laser scanner becomes more of a necessity for creating the model.

There is no question about the potential value of modeling the urban environment in 3D. From historical preservation, to urban planning to environmental modeling 3D adds significant value to the application. The key is going to be in developing the business case to justify the investment. It is not unlike the early days of GIS, but look where that has gone.

Developing these higher order models is one of the largest potential markets for 3D laser scanning.