From time to time users may encounter situations where high resolution GIS is not ubiquitous around a site. It is important to understand the behavior of cnHeat to create the most accurate predictions possible.
Depending on the terrain, jumping over these voids may be completely acceptable and may not affect the accuracy of the prediction. However please keep in mind that these voids represent areas of unknown. Any obstructions in these areas are not being accounted for in the predictions. They could be adversely affecting predictions and showing coverage that is more optimistic than actual.
Here is an example.
If a user is ever in doubt about planning a site in this way we recommend opening a ticket with support to have our cnHeat team investigate.