In some cases, you can use in the "Tools Palette" and it can be recognized during the creation of the dimensions. It is always possible to add these points manually and after using them, create the dimensions. The blue lines and the intersection points are not visible when the document is outside CATIA (printed or in CDD).

If you want to understand more details and how to represent the prolongation lines to the intersection point, please open the following document.

 Intersection Point in a Drawing