Reconstruct from a video

Introduction

It is possible to build a reconstruction using a video file instead of still images. The technique for reconstructing the camera trajectory from a video is called Simultaneous Localization And Mapping (SLAM). OpenDroneMap uses the opensource ORB_SLAM2 library for this task.

We will explain here how to use it. We will need to build the SLAM module, calibrate the camera and finally run the reconstruction from a video.

Building with SLAM support

By default, OpenDroneMap does not build the SLAM module. To build it we need to do the following two steps

Build SLAM dependencies

cd SuperBuild/build
cmake -DODM_BULID_SLAM=ON .
make
cd ../..

Build the SLAM module

cd build
cmake -DODM_BULID_SLAM=ON .
make
cd ..

Calibrating the camera

The SLAM algorithm requires the camera to be calibrated. It is difficult to extract calibration parameters from the video's metadata as we do when using still images. Thus, it is required to run a calibration procedure that will compute the calibration from a video of a checkerboard.

Running OpenDroneMap from a video