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Automated Airphoto Orthorectification and Mosaicking in Modeler

PCI Geomatics -

In Geomatica, you can use the integration capabilities between Focus and Modeler to create custom models and combine tasks using batch processing.

This tutorial shows you how to create a model to import, orthorectify and mosaic standard aerial photography. A sample dataset required to run this AirPhoto Model is available at:

Note: The dataset should be extracted to your C:\ drive where a new “AirPhoto_Modelling” directory will be created. You can also extract the data to any other location and modify the paths of input and output files in the model.

1. Open the Modeler application from the Geomatica toolbar.


2. From the Modeler menu bar, select File > Open Model and select the downloaded AirPhoto_Ortho.mod file. The following model will load in Modeler:


3. To process the mosaic, on the toolbar, click Run Batch 


  • The two IMPORT modules are used to import the four provided air photos in batch mode, and the provided digital elevation model (DEM) to be used for orthorectification.



  • The GCPREAD module is used to read four ground control point (GCP) text files in batch mode, which are to be used with the imported air photos.
  • The GCPs were collected using the projection UTM 17T E012, and contain elevation values (They are 3D GCPs).



  • The ACCUMULATE module is used when more than one image or segment must be passed at once to the next module. The CRPROJ module requires that all input images and GCPs must be added at once.
  • The ACCUMULATE module is also used before AUTOMOS, where all ortho images are required to be passed at once.



  • The CRPROJ module is used to create an OrthoEngine project which contains the previously imported air photos and GCP text files.
  • Since we are working with standard aerial photography, the Model Type should be set to
  • The Output Projection we will use is UTM 17T E012.



  • The CAMIMPORT module accepts a Camera Calibration File, which contains important information regarding the sensor used to acquire the air photos. The file xml has been provided for this demo.



  • The AUTOFID module performs the automatic collection of fiducial marks.   A Fiducial Chip Database has been provided which contains the fiducial marks for the four imported air photos.



  • The AUTOTIE2 module performs tie point collection on the set of aerial photos in an OrthoEngine project.



  • The APMODEL module performs a bundle adjustment on a set of aerial photos with ground control points (GCPs) and/or tie points (TPs) in an OrthoEngine project.



  • The RELEASE module will take multiple images or segments and break them up into a single image or segment per iteration. This is required for the ORTHO2 module, as the output from APMODEL contains the models for all air photos, where ORTHO2 only accepts one air photo and model at a time.


ORTHO2 Module

  • The ORTHO2 module performs orthorectification on the air photo project. The DEM previously imported also is used for this process.
  • It is important to set the Background Elevation Value in this module, or the orthorectification step will assume elevation values of -150 are valid.



  • The AUTOMOS module composes a set of georeferenced air photo images (created in ORTHO2) into an image mosaic, or into a series of mosaic tiles.



  • The EXPORT module writes all input port data to an output file.
  • For this tutorial the mosaic, vector cutlines, and look up tables (LUTs) are exported to a single PIX file.


Output Mosaic

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