5.3. Images and processing routines

This section provides an overview of important steps in processing UAV images prior to information retrieval. The primary output of the processing steps is normally an orthophoto (i.e., a seamless image obtained from multiple raw images, that has been corrected for terrain distortions). From it, several other information products can be derived. Good practices are shared below.

UAV platforms normally come with one or more associated software packages for processing the images. Pix4D and AgiSoft are  two applications that are commonly used. Other used software packages included CAN-EYE and Microsoft ICE. The purpose of this knowledge portal is not to reproduce the respective manuals of these applications, but to share with the reader experience gained in those processing steps that could be tricky.

Irrespective of the software used, there are generally four steps to follow. These are:

  1. loading and stitching images,
  2. generating and editing the derived point cloud,
  3. digital surface model generation, and
  4. constructing the orthophotos.