Make sure you have updated ArcGIS to 2.8 or higher.
Make sure you have updated ArcGIS to 2.7.
## 3. Download source codes:
[Download](https://gitlab.itek.norut.no/jakob/vpi-toolbox#releases) the VPI toolbox and unzip it to a path of your choice, from now on referenced to as `C:\path-to-vpi-codes\`.