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Sentinel-1 Orthorectification

PCI Geomatics -

Introduction

Sentinel-1 is a synthetic aperture radar satellite which provides continuous imagery day or night and through all weather conditions. The following is a brief tutorial showing a step by step procedure for generating an orthorectified image from Sentinel-1 data. Please note that you can only orthorectify Sentinel-1 Ground Range Stripmap mode data. There is currently no way to orthorectify GRD IW or EW data in OrthoEngine other than using a 2D polynomial math model, thin plate spline math model or the rational function model (compute from GCPs) because the data is delivered in different sub sets and does not contain the required orbit information. Sentinel-1 data is freely available and can be downloaded from The Sentinels Scientific Data Hub.

For more workflows using Sentinel-1 data please see PCI TV.

 

Project Setup

  1. Open OrthoEngine from the Geomatica toolbar.

  1. From the OrthoEngine toolbar click on File > New

 

  1. The project Information window opens.
    • Enter a Filename for the project. Browse to your destination folder with the Browse Name the project and enter a description.
    • In this window, under Math Modeling Method, choose Radar Satellite Modelling.
    • Under Options select Toutin’s Model.
    • Click OK

  1. The Set Projection window will open up. Click Cancel to close this window. The projection information will automatically be set once you add your first image.

 

 

Open Image Files in OrthoEngine

  1. On the OrthoEngine toolbar select Data Input from the Processing Step drop down menu.
  2. Select Read PCIDISK file

  1. In the Open Image Window click Add Image.

Note: Sentinel-1 data is directly supported in our generic database library. To add a Sentinel-1 image to the project simply select the manifest.safe file.

 

  1. Navigate to the folder location and type *.* in the file name box and hit return to display the manifest.safe file

 

  1. Choose the calibration type.

 

  1. Click Yes to impot the data file to a PIX and Yes to create overviews.

  1. The file is now loaded into the project as a PIX file for further processing.

 

GCP and TP Collection (Optional)

  1. On the OrthoEngine toolbar change the processing step to GCP/TP Collection. Choose Collect GCPs Manually or Collect GCP Points Automatically.
  2. You should collect 6-8 GCPs to produce the most accurate model.

  1. If there are multiple overlapping images in your project you can also collect tie points to improve the model.
  2. From the OrthoEngine toolbar choose Collect Tie Points or Automatically Collect Tie Points.

 

Compute Model

  1. On the OrthoEngine toolbar change the processing step to Model Calculations. Choose Compute Model.

 

 

Ortho Generation

  1. On the OrthoEngine toolbar change the processing step to Ortho Generation. Choose Schedule Ortho Generation.
  2. The Ortho Image Production window opens.
  3. Move the image from the Available images window on the left to the Images to process window on the right.
  4. Select an output folder location for the output.
  5. Select a DEM For this tutorial gmted2010.pix was selected. This file can be found in the etc folder - C:\PCI Geomatics\Geomatica 2016\etc
  6. Modify any of the other parameters based on your data requirements.
  7. Select Generate Orthos.

  1. The final orthorectified image can be viewed in Focus.

  1. If you have Google Earth installed you can export the orthorectified image to a .kml file to check the accuracy.
  2. In Focus click on File > Export to Google Earth…

  1. Browse… to an output file name and location.
  2. Checkmark Display results in Google Earth.
  3. Click Export

  1. Your orthorectified image should overlay nicely.

 

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