Between the Poles

Using BIM techniques to transform highway and road construction

A very interesting article by engineers from Sundt Construction, Tempe, Arizona, about applying some of the techniques used in vertical construction (tall buildings) to horizontal construction (highways, roads bridges). It's particulary interesting because it is another example of the convergence of BIM and geospatial technology.

One of the efficiencies that is gained in the construction of tall buildings is that with the exception of one or two ground level floors, the foundation and top floors, floor designs are identical.  Horizontal construction is more complex than vertical construction because of ground topography and existing infrastructure.  Because of this complexity Sundt says that horizontal construction could benefit more than buildings from building information modeling (BIM). Sundt uses the term "virtual design and construction technology (VDC)" for BIM for horizontal construction, others use "BIM for infrastructure".  Sundt has been working to transfer lessons learned in vertical BIM to highways and bridges.

A VDC project begins with a site model built on a 3D laser scan, typcially accurate to within a millimeter. Horizontal projects have to be very concerned with existing underground infrastructure.  The clash detection technology used in vertical projects to detect interferences between water, HVAC, structural and other subsystems can be used in a VDC project to avoid clashes with water, wastewater, electric power, telecommunications, and other underground infrastructure.  This highlights the importance of having an accurate 3D geospatial model of underground infrastructure, which is still lacking in many jurisdictions.

One of the ways VDC projects can achieve a degree of repeatability is through "subassemblies" which are used to parametrically model features, road surfaces, retaining walls, typical road details, bridges, grading standards, rail tracks, and utilities. With a digital terrain model (DTM) a VDC model can be used to calculate every foot of trench from exact existing elevations and exact trench depths and apply a slope formula to figure out the exact amount of excavation required.  And VDC models can be provided directtly to construction subcontractors enabling them to more easily add schedules (4D); and budget (5D) to the 3D model.

Sundt says that VDC is an improved process for collaboration between all players in the construction process including owners, surveyors, designers and engineers, and construction contractors.  In the future Sundt plans to create construction-ready VDC models for horizontal projects because they have the potential to transform the construction process, from surveying to paving to recording as-built information.

CE NEWS in the August print edition will be also be publishing an article that will include some of Sundt's BIM for infrastructure projects in the U.S.

BIM for Infrastructure: Infrastructure Modeler available in more languages

Earlier this year, Autodesk announced new software for conceptual design as part of its BIM for Infrastructure portfolio. Infrastructure Modeler represents the convergence of design, GIS and 3D visualization and is intended to help users create models that represent the existing natural and built environment using GIS, digital terrain models, CAD, BIM, and a variety of imagery data; sketch and evaluate multiple alternative conceptual designs for projects; and use 3D visualization technology to communicate what these design alternatives will look like to stakeholders.

Infrastructure Modeler 2012 is now available in French, German, and Simplified Chinese versions. Portuguese, Russian, and Japanese versions are expected soon.

New ASTER global digital elevation model

In 2009 NASA and the Japanese Ministry of Economy, Trade, and Industry (METI) released the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) global digital elevation model (DEM), which covers about 99% of the Earth's surface. The global DEM was built from 1.5 million individual scene-based ASTER DEMs. The global DEM is in GeoTIFF format with lat/long coordinates and a 1 arc-second (30 m) grid.  It is referenced to the WGS84/EGM96 geoid. Accuracy is estimated to be 20 meters for elevations and 30 meters for horizontal data.  

Based on measurements from NASA’s Terra spacecraft, a new 3D topographic map has been released, again as a joint effort by NASA and Japan.  An additional 260,000 additional stereo-pair images were added to enhance the latest version of the DEM.

The ASTER global DEM V2 is available at no charge to users from the Earth Remote Sensing Data Analysis Center (ERSDAC) of Japan and from LP DAAC.

Map Malaysia: Sea level rise and flood management is a top priority in Sabah

I'm in Malaysia this week and yesterday I had the opportunity to give a presentation in the plenary session at Map Malaysia in Kota Kinabaru, Sabah on Borneo, the world's third largest island as we were informed by one of the speakers.

The opening address was given by Sabah Deputy Chief Minister Dr Yee Moh Chai on behalf of the Chief Minister Seri Musa Haji Aman.  The Chief Minister said that the government is committed to the development of geospatial infomation in Sabah.  He said that he wants to expand the use of  geographic information in Sabah beyond traditional applications such as mapping, disaster management, water and natural resources management  to business, design and engineering, social networking, energy, GHG emissions, and climate change.

A plenary speaker, Haji Safar bin Utong, Deputy Director of the Lands and Survey Department Sabah, reiterated the government's committment to the expansion of geographic information but identified some issues that he feels very strongly need to be addressed.  In addition to limited funds for data acquisition from companies like Intermap, who have mapped a terrain model of all of Malaysia at about one meter vertical resolution, he also identified the issue of data sharing within the government.  Sabah has a geospatial data portal, MyGeoportal, but only 16 of 200 government agencies use it and even among those 16 agencies, there is limited sharing of geospatial data.  I think it is fair to say this is a very real problem with most governments.

Water

Water is a major concern in Malaysia.  In the last few days there has been major flooding in Perlis, which has displaced thousands.  And there is the issue of rising sea level. According to global climate statistics published by NASA, global sea level rose 17 cm in the last century. The annual rate for 2000-2010 is double the annual rate for the last century.  According to some projections the rate of sea level rise is expected to accelerate in the coming decades.  According to the Director of  the Sabah Lands and Surveys Department, his department is in the process of establishing a 3D simulation system for flood management.  Digital terrain elevation data is being acquired (from Intermap), beginning with coastal areas. Based on preliminary results, for example, a rise in one meter of sea level will affect parts of Kota Kinabalu, but a rise of 3 meters would result in 90% of Kota Kinabalu being covered by water.  According to NASA, south east asia is one of the areas where sea level rise has been the highest.

The east coast of Sabah is an area that has been identified as a risk area for tsunamis.  One of the presentations described a project to produce tsunami risk maps for the east coast of Sabah that used digital terrain models and overland flow modelling to prroduce tsunami hazard maps.

Open Data and Project Galileo at the City of Moose Jaw

There are several Moose motivated cities and towns in Canada, Moosonee, Moose Factory, and so on.

But the largest is Moose Jaw, Saskatchewan.  Bret Rowlinson, GIS Supervisor, at the City of Moose Jaw has prepared a very cool video showing how he created a 3D model of the city with the Autodesk Labs Project Galileo using freely available datasets including a terrain model, water bodies, road network, and parcel files and used it to assess a proposed development project.

GIS for Architects

I've blogged about an Autodesk Labs project called Galileo. Galileo is a technology preview for 3D city modeling for planners, architects, and designers, who need to view future designs of structures in the context of their intended urban environment. 

The product manager for Galileo, Chris Andrews, has posted some tips for architects and non-GIS folks who want to use geospatial data, but may not be familiar with geospatial data sources and how to use them.

The questions he answers are

Q: What is a shapefile and where do I get one?

Q: Where would a database file come from and how would it be used?

Q: How does a terrain surface file work with an image file and where would I find it?

Q: How would a terrain texture file be used?

Q: Which is the most efficient file format to import from for an Architect? (FBX, OBJ…) 

Q: What is LandXML data and where does it come from?

Q: What are coordinate systems and which should be used?

FOSS4G Frank Warmerdam on Vertical Datums

There is a lot more interest in three dimensional surfaces these days and this is also reflected in the open source geospatial world. This afternoon at FOSS4G in Barcelona, Frank Warmerdam gave a talk on the subject of Vertical Datums: Introduction and Software Review to a standing room only audience.

He summarized the different models for elevation measurement including the traditional elipsoidal, tidal and orthometric.  (The image shows the divergence between the geoid (EGM 96) and elipsoidal (WGS 84) models for representing the Earth.) He described some of the challenges in working with vertical coordinate systems, such as the difficulty in relating EPSG to OGC vertical coordinate systems.

The good news for the open source geospatial community is that Frank is working on extending several open source libraries to support vertical datums including

    * Liblas
    * Libgeotiff
    * GDAL
    * PROJ.4

He mentioned that CS-MAP already supports vertical datums and in particular provides extensive transformation grid files (gtx) for transforming between different models.  Proj.4 and CS-MAP are both part of the OSGeo MetaCRS project that Frank chairs.

New German Radar Satellite TanDEM-X

The new German radar satellite, TanDEM-X,  which was launched from Kazakhstan earlier this week has returned its first images. Together with the TerraSAR-X satellite launched in 2007 it will be able to produce digital elevation models to a precision of better than two meters.

The Canadian RADARSAT II was launched at the end of 2007 and provides digital elevation models with a highest resolution of 3 meters, but typically less.