Question

How to aggregate OD pairs and display them as Desire lines?

Answer

1) Define Main Zones

The first step in aggregating OD pairs is to define Main zones. Multiple Zones can be related to a Main zone.

2) Create a Main Zone Matrix

Once the Main zones are defined, create a Main zone matrix from an existing OD matrix. To do this, follow these steps:

2.1 Add a new matrix and select the option "Matrices with Main zone dimension"

2.2 In the procedure sequence, under the "Matrices" section, choose the "Matrix Aggregation" procedure.

2.3 Set the Reference Object to the empty Main zone matrix.

2.4 In the procedure parameters, select the demand matrix that you want to aggregate.

3) Display Aggregated OD Pairs

After creating the Main zone matrix, configure the graphic parameters to display the aggregated OD pairs:

3.1 Go to the graphic parameters for Main OD pairs (Desire lines main zones → Display).

3.2 Set the ScaleAttrID to "Matrix Value" and select the aggregated matrix.

3.3 This will display the aggregated OD pairs as bars or lines between the Main zones

Alternative Method

Alternatively, for smaller projects, you can skip the matrix aggregation procedure and directly display the aggregated values:

1. In the graphic parameters for Main OD pairs, select an indirect attribute of the Main zones.

2. Choose "OD Pairs → SUM (...) → Matrix Value" for the ScaleAttrID.

While this method works well for smaller projects, it is not recommended for larger projects due to performance limitations.