Flying a roof, while taking off from the ground may present challenges. The overlap values indeed depend on the height of the building. This means that despite planning a flight with an optimal overlap at ground level, the overlap may be much lower at the roof level.
The following process will help you make sure that the overlap values are correct, even at roof level.
1 - Estimate the height of the roof. For tilted roofs, note the height of the highest part
2 - Prepare your mission in GSPro, without taking the building into account.
- For the height, do not use the total height for the flight, start by introducing the height as if there was no building. For example, if you want to fly 34m above the roof, start by planning the mission at 34m above the ground.
- For the overlap, use the usual values (for example 80-80)
- Note down the estimate of the duration of the flight.
3 - Modify the mission to take the building height into account
- Add the height of the roof to the height of the flight. If the roof is 10m high, add this to the 34m to get to 44m in total.
- You will see that the duration of the flight will have gone down significantly at this stage
- You will now have to increase both overlap values (front and side), until the flight duration reaches the time calculated in point 2. Do not forget to make sure the front and side overlaps have the same value. Typically, for a roof of 10m, the overlap will have to go from 80% to approximately 86%.
You can now fly your mission with the guarantee that the overlap at the roof level will be the nominal one.