A Comparison of Image Aligning and Correcting Software with an Unmanned Aerial System Kangsan Lee, Jinwoo Park, Jinmu Choi 1

Contents Introduction Data Acquisition – Image Gathering – Correcting Lens Distortion Image Alignment – Image Alignment Software – Comparing Image Stitching Software – Results Conclusion Spatial Analysis & GIS Lab2

Introduction Why Unmanned Aerial System: Drone  Aircrafts & Satellites: Major role in Remote Sensing  Structural problems: Time, Cost and Weather condition  UAS, Drone...? Purpose of study: Comparing image stitching softwares  Variety of softwares in the market  Each software was developed ‘On their own needs’ Spatial Analysis & GIS Lab3 Q. What is the suitable program for small UAS system?

Data Acquisition Image Gathering – Hardware: 3DR Robotics IRIS+(Drone) and GoPro(Camera) are used – Area of interest: Baramarae beach - west coast of South Korea – App. 200 images are collected and used (Flight date: Jan, 2015) Spatial Analysis & GIS Lab4 Figure 1. IRIS+ and GoPro (Right), Mission Planner for autonomous flight (Left)

Data Acquisition Correcting Lens Distortion – GoPro(small digital camera) has a lens distortion (Tauro et al., 2014) – Adobe Lightroom is selected to remove lens distortion Spatial Analysis & GIS Lab5 Figure 2. Lens distortion correction (before – later)

Image Alignment Experimental Design Spatial Analysis & GIS Lab6 ComponentSpecification CPUIntel Xeon CPU E GHz RAM16GB (DDR3, Dual Channel) GPUGeForce GTX 750Ti Cuda Core640 StorageSSD, 256GB Table 1. Specification of the testing environment Computing Environment Processing Time Total Image Volume Image Quality

Image Alignment Image Alignment Software – Five major software are selected to test about stitching performance – Open-Source software(GPL); Hugin – Commercial software; Photoscan, Photoshop, MS ICE, Pix4D Spatial Analysis & GIS Lab7 NameDeveloperLicenseNotes PhotoscanAgisoftProprietaryUsing photometry method PhotoshopAdobeProprietaryUser-friendly interface Image Composite Editor MicrosoftProprietary (Free for non-commercial use) Variety of pre-defined projection HuginPablo d'Angelo et al.GPLBased on panorama tools Pix4DmapperPix4D SAProprietaryOptimized for UAS Table 2. Software information

Image Alignment Comparing image stitching software – The amount of input data has been changed; range from 50 to 200 Spatial Analysis & GIS Lab8 Figure 3. Concept of software comparing experiment

Image Alignment Results Spatial Analysis & GIS Lab9 1) Processing Time Gradually increased MS ICE → Fastest Hugin → X working: Software limitation Photoshop → X working 150↑: Hardware limitation

Image Alignment 2) Image Volume Image volume gradually increased according to numbers of images MS ICE exports the lowest volume Photoscan shows the highest rate of increase Spatial Analysis & GIS Lab10

Image Alignment 3) Image Quality Photoscan shows the best quality without any problem MS ICE and Photoshop have some distorted Pix4D cannot calibrate colour and image matching Spatial Analysis & GIS Lab11

Conclusion Limitation – Researchers can easily find alternative Open-Source software – But the performance of open-source software does not reach to commercial one Potential – The potential of open-source software is sufficient – E.g. Visual SFM became the best 3D image reconstruction open-source software Future Market – The sales market of UAS(Drone) have been increased – Needs of image stitching will be increased in the near future Spatial Analysis & GIS Lab12

Thank you