2.4.2 Geometric process

In the frame of remote sensing process, one common operation is to be able to superpose and manipulate data which come from different sources. This section gives access to a large set of geometric operations. It performs re-projection and orthorectification operations on Optical or SAR dataset using the available sensor models (image informations available in the meta-data are automatically read by the application).

Reprojection module

The application is derived from the otbOrthorectificationApplication in the OTB Applications package and allow to produce orthorectified imagery from level 1 product. The application is able to parse metadata informations and set default parameters. The application contains 4 tabs:


PIC

Figure 2.11: Reprojection module. Quick Look tab.


Estimating sensor model based on ground control points

This module allows to take ground control points on a raster image where no geographic informations are available. This GCPs list is making correspondence between pixel coordinate in the input image and physical coordinates. The list allows to derive a general function which convert any pixel coordinates in physical positions. This function is based on a RPC transformation (Rational Polynomial Coefficients). As a consequence, the module enriches the output image with metadata informations defining a RPC sensor model associated with the input raster. There are several ways to generate the GCPs:

It is also possible to import/export the list of Ground Control points from/to an XML file.

Moreover, if the input image has GCPs in its metadata, the module allows to add or remove points from the existing list, which is automatically loaded.