The Virtual Iowa City project was begun as a development initiative at the National Advanced Driving Simulator. The project is intended to demonstrate capabilities and uses of the NADS MiniSIM, a low-cost portable simulator that uses the same core technology as the larger NADS-1 and NADS-2 simulators.
Real-time: The Virtual Iowa City project is designed as an interactive, real-time environment. This is different from animation, which uses a pre-rendered series of images to convey motion. In a real-time environment, the scene is being rendered up to 60 times each second, and the view is updated dynamically as the viewer eyepoint traverses the environment.
We would like to acknowledge the City of Iowa City Engineers Office for providing access to the data which has been used as reference and a basis to construct this virtual environment. CAD and LIDAR source data was used in conjunction with satellite imagery to identify landmarks and as a basis for 3D model construction.
This shows satellite imagery from BING overlaid on vector data and aligned to match significant landmarks. In cases where imagery does not align with the vector data, the vector data takes precedence over the imagery.
The green patch in the center of the image shows a non-ordered polygon patch created from LIDAR data.
This shows source vector data digitized from LIDAR or satellite imagery. The data was provided in digitized form. This data was used as the baseline starting point for development, since all major features have been identified. In cases where imagery does not align with the vector data, the vector data takes precedence over the imagery.
The road network is constructed using the topographical isolines as major guidelines for road elevation. Some of the roads and intersections have been created.
The road network is constructed from a combination of sources. The road centerline vectors do not contain enough resolution to create smooth splines for use in the simulator, so they are being replaced by creating high resolution roads and intersection objects. There are also some simulator conventions which must be followed on the road network.
These conventions are visible as discrete intersection elements with defined corridors for simulator vehicles to traverse the environment properly.
The process of creating a high resolution 3D intersection begins with LIDAR data. The LIDAR data contains coordinates and a surface code, which was used to determine a bare earth return. The LIDAR area of the intersection was partitioned from the surrounding data and exported to a unique file. These coordinates were then imported into the modeling environment as an non-ordered point mesh. A normalized polygon mesh as shown here is created by slicing the non-ordered point object and removing points that do not align on the grid.
Virtual Iowa City photographic surveys were conducted over a period of days during 2009. Photographs were taken during cloudy days to maximize the ability to use the images for texture map source. A large number of photographs were used for close-in situational awareness in addition to texture source.