Hi,
I use images from a fixed wing drone, we use Microsoft ice for mosaic and agisoft for 3d model. In agisof you can do camera calibration and do ortophoto, work very good. Try to find this book! will answer all your questions.
James S. Aber, Irene Marzolff, Johannes Ries, "Small-Format Aerial Photography: Principles, techniques and geoscience applications