Open GIS is a solid foundation for BIM. Part 1

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Note: This article is written and published in Ukrainian and is a translated version of the original published here.

The development of the University Hospital of Zurich (Universitätsspital Zürich, USZ) is planned until 2049, so it was important to create a conceptual and functional model of all existing and planned buildings with a division into functional zoning in order to optimize it. Because the hospital is open to everyone every day, offers basic care and advanced treatments, it was important to develop and calculate different planning options to minimize the impact on existing treatment, education, and research processes.

Our work consisted in technical support of design processes, namely in the creation of BIM (Building Information Modeling) of building models (LOD100) based on various input data – measurement and archival drawings, point clouds, etc. Also, one of the important tasks was to model the relief of a large part of the city of Zurich with buildings based on geographic information data (GIS) and the results of ground-based laser scanning. This was necessary for a visual assessment of the planned development, so that the new buildings would not overlap or spoil the view of the picturesque lake from the hills – this is where we start.

View and access location data - City of Zurich

GIS (Geographic Information System) of municipal or state importance plays a great role in the implementation of BIM, because in the presence of these open and up-to-date data, it is possible to solve many applied problems in a very short time. We used data from the official resource of the city of Zurich -Geodaten betrachten und beziehen - Stadt Zürich, which contains more than half a thousand different geodata records. For example:

Relief contours (SHP).

Section and Road Contours (SHP).

Models of houses and structures (DXF).

Orthophotography andschematic maps (TIF).

Classified Lidar Scan (LAZ).

LoD2 3D Roof Model, Status 2015 (3D)

The most important thing is that all this data is placed in different formats, in a single coordinate system and can be imported or connected to Autodesk InfraWorks and Civil 3D. First of all, we connected all this data to Civil 3D and made sure that they are all combined and integral. Geometry from the SHP format is imported through a separate command MAPIMPORT, which also allows you to attach data attributes that may contain useful information, in particular on terrain areas. Dot clouds from lidar scanning (LAZ) in Civil 3D are attached only in the Autodesk Recap format, so we pre-processed them in it and reduced the density of dots for better performance.

For each individual dataset, we created a separate Civil 3D file and combined them with external links for the possibility of further joining in Autodesk InfraWorks and Revit. We received floor plans of buildings without reference by coordinates, so we had to combine them manually along the contours of buildings from the geoportal.

Next, we created a primary model of a part of the city in InfraWorks based on OSM data that is automatically generated by the Model Builder application. Unfortunately, the generated model has a very simplified relief, satellite imagery, the shapes of buildings and incorrect widths of roads, and especially their intersections. We need it only at the beginning to make sure that the size of the area is sufficient. Next, we sequentially create options in which we delete unnecessary data elements and attach new ones:

We remove houses, roads, plots.

We attach new relief contours.

Delete the Bing Map satellite imagery and attach a schematic map.

We attach the buildings and the contours of the plots.

Attach a dot cloud to hide extra classes.

Then we will connect building models of different development options with Revit and be able to visually evaluate it from different angles. We exported the InfraWorks terrain model to Civil 3D via IMX format, and the topographic surface obtained in it was transferred to ACC (Autodesk Construction Cloud) and attached to Revit along with existing houses in DWG format. Next, we performed ground-based laser scanning and created building shapes based on premises with tricky export-import through IFC, which we will talk about in the next post.