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Thomas Brinkhoff: Network-based Generator of Moving Objects

Frequently Asked Questions

What do the output columns mean?

The reporting depends on the Reporter class that is used and the type of the output file. The DefaultDataGenerator uses the class PositionReporter (the source code of both classes and of other Reporter classes are included in the source code download). The type of output file is determined by the contructor of the Reporter class considering the file extension. The two print methods determine the reported parameters. For details, take a look into the source code of the relevant Reporter class.

How can I specify external objects that never disappear?

This is possible by modifying the values of the attribute lifetime in the class ExternalObjectClasses (its source code is included in the source code download). The values of this array are set by the constructor. In the default implementation they are set to 10. Use Integer.MAX_VALUE instead.

Does your implementation guarantee a constant number of moving objects?

There are several versions of the generator. If you use the version ConstantDataGenerator instead of the DefaultDataGenerator, the class ConstantObjectGenerator controls the number of moving objects (for details see its source code which is included in the source code download). The batch file starting the generator must be modified accordingly.

How are the properties (e.g., speed) of the classes of objects is specified?

This is controlled by the class ObjectClasses (its source code is included in the source code download). The speed is defined by the attribute speed and set by the constructor.

What do the output coordinates mean?

In case of the "Oldenburg" and the "San Joaquin" file, they have no meaning.

If you use the ShapefileNetworkFileManager for generating the network files, the data space of the coordinates will be transformed into a rectangle (0,0) x (resolution, resolution). You'll get the original coordinates by performing the inverse transformation.

If you use the TigerManager for generating the network files (or the "San Francisco" file):

  • longitude = (outputX/1000000) - 180
  • latitude = 90 - (outputY/1000000)

The TigerManager crashed when I read a Tiger file. What is the reason?

Depending on the tiger file version (or if the text input files have become Unix/Linux text files), the record size or/and the record format of the file may differ. To solve this problem, you have to adapt the methods getRecordSize and read in the class ChainBasicData.

Last update: 2006-03-09


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