# Processing UAV images in OrthoEngine

PCI Geomatics -

Introduction

This tutorial outlines the steps taken when processing UAV images in Geomatica OrthoEngine. The following project was created using 59 images acquired with a DJI Inspire 1 drone and PIX4D software.

OrthoEngine

1. From the Geomatica toolbar click on the OrthoEngine application.

1. The OrthoEngine toolbar opens. Click on File > New
2. The Project Information window opens. Enter a filename and location for your project file.
3. Enter a name and description
4. Select Aerial Photography as the Math Modelling Method
5. Select Digital/Video as the Camera type
6. Select User input as the Exterior orientation
7. Click OK

1. On the OrthoEngine toolbar select the Set Projection icon

1. Enter an output projection and pixel spacing

1. On the OrthoEngine toolbar select the Set Camera Calibration icon

1. Enter the focal length, chip size and any distortion information you have available. This information is specific to the camera you are using. Note that focal length and chip size are required parameters.

Below is a sample Pix4D camera report. These values need to be modified using the following equations to create an output in PCI Geomatics Software.

CanonIXUS127HS_4.3_4608x3456

#Focal Length mm assuming a sensor width of 6.1700014080000001x4.6275010559999998mm

F 4.3931935121825934

#Principal Point mm

Px 3.2122823277299526

Py 2.4413916780297322

#Sensesor size mm

Sw 6.1700014080000001

Sh 4.6275010559999998

#Symmetrical Lens Distortion Coeffs

K1 -0.047897940118842249

K2 0.041337213391237804

K3 -0.014500837979654166

#Tangential Lens Distortion Coeffs

T1 0.0064328935211232395

T2 0.0062981163596038192

Calculate the principal point offset (PPO) using the formulas below then enter the values into the corresponding text field in the Digital/Video Camera Calibration Information window.

X= Px – (Sensor width/2 )
Y =(Sensor height/2) -Py

Calculate the distortion values using the formulas below then enter the values into the corresponding text field in the Digital/Video Camera Calibration Information window.

R3 = -K1/ F ²

R5 = -K2 / F ⁴

R7 = -K3 / F ⁶

P1 = -T2 / F ²

P2 = -T1 / F ⁴

1. Click OK

1. On the OrthoEngine toolbar select the Data Input Processing step

1. Select Open a new or existing image
3. Click Close
4. On the OrthoEngine toolbar select Import exterior orientation data from text file

1. The import exterior orientation data from text file window opens
2. Change the Input projection accordingly. If this information is entered incorrectly, your output mosaic will not be accurate.
3. Click on Browse to the right of Text file and navigate to the exterior orientation file for the project
4. If you know that some of your images need to be rotated, do this now by rotating the kappa values for each image.
5. When done, click Import

1. Now is a good time to save your project. On the OrthoEngine toolbar click on File > Save
2. On the OrthoEngine toolbar select the GCP/TP Collection Processing step
3. Click on the Display Project Overview This window allows you to quickly see all of the images in your project and their relation to each other. Any inaccuracies with projection, distortion, scale or exterior orientation will be visible here by simply looking at the frame and position of the images.

1. On the OrthoEngine toolbar select the Model Calculations Processing step
2. Select Compute Model

1. On the OrthoEngine toolbar select the Ortho Generation Processing step
2. Select Schedule ortho generation

1. Move the available images to the Images to process window
2. Select an output location for the orthoed images
3. Select a DEM file
4. Click Generate Orthos

1. On the OrthoEngine toolbar select the Mosaic Processing step
2. Select Define mosaic area

1. Select an output file name and location for your mosaic file.
2. Using the select images to be mosaicked tool draw a box around all of the images in the display.
3. Click OK

1. On the OrthoEngine toolbar select Automatic mosaicking

1. The Automatic Mosaicking window opens.
2. Modify the settings accordingly.
3. Select Generate Preview to view your output.
4. Once you are content with your changes, click on Generate Mosaic.

1. Your project is now complete. To view your mosaic, load the file into Focus. Some inaccuracies are seen in the mosaic below. This is due to the accuracy of the DEM. Changes can be further made to the mosaic using the Live DEM Editing Tool in Focus.