The altitude of your flight will depend on the type of aircraft you select, and the sensor quality it possesses. In general, for aerial imagery, we recommend a flight altitude of 150 ft along with a 20-megapixel camera resolution and 0.5-inch ground sampling distance (GSD). For aerial LiDAR, it is dependent on the number of returns and beam divergence. If your sensor has multiple returns and low beam divergence, you can fly around 250-300′ and collect a point cloud with low noise/distortion and a high level of detail; as you have fewer returns or more beam divergence over a shorter distance, you need to reduce flight altitude to be closer to 150′.
That being said, your flight altitude can be higher or lower depending on the accuracy requirements of your specific project. Accuracy is also dependent on the number and distribution of ground control points, the control collection methods, and processing techniques.