4.1.1 Opening a Pleiades image in Monteverdi

Opening a Pleiades image in Monteverdi is not different from opening other kind of dataset: use the Open Dataset item from the File menu, and select the JP2 file corresponding to you image using the file browser.


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Figure 4.1: Dialog window when opening a Pleiades image in Monteverdi



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Figure 4.2: Pleiades images in the main Monteverdi window


Figure 4.1, page 165 shows the dialog box when opening a Pleiades image in Monteverdi. One can see some changes with respect to the classical dialog box for images opening.

The first novelty is a combo box allowing to choose the resolution of the Jpeg2000 file one wants to decode. As said in the introduction of this section, Orfeo ToolBox can take advantage of Jpeg2000 capability to access coarser resolution ver efficiently. If you select for instance the Resolution: 1 item, you will end with an image half the size of the original image with pixels twice as big. For instance, on a Pleiades panchromatic or pansharpened product, the Resolution: 0 image has a ground samping distance of 0.5 meters while the Resolution: 1 image has a ground samping distance of one meter. For a multispectral product, the Resolution: 0 image has a ground samping distance of 2 meters while the Resolution: 1 image has a ground samping distance of 4 meters.

The second novelty is a check-box called Save quicklook for future re-use. This option allows to speed-up the loading of a Pleiades image within Monteverdi. In fact, when loading a Pleiades image, Monteverdi generates a quicklook of this image to be used as a minimap in the Viewer Module as well as in the Uncompress Jpeg2000 image module. This quicklook is the coarser level of resolution from the Jpeg2000 file: it should decode easily, but can still take a while. This is why if the check-box is checked, Monteverdi will write this quicklook in uncompressed Tiff format next to the Jpeg2000 file. For instance, if the file name is:

IMG_PHR1A_MS_201204011017343_SEN_IPU_20120529_1596-002_R1C1.JP2

Monteverdi will write, if it can, the following files in the same directory:

IMG_PHR1A_MS_201204011017343_SEN_IPU_20120529_1596-002_R1C1.JP2_ql_by_otb.tif  
IMG_PHR1A_MS_201204011017343_SEN_IPU_20120529_1596-002_R1C1.JP2_ql_by_otb.geom

Next time one will try to open this image in Monteverdi, the application will find these files and load directly the quicklook from them, instead of decoding it from the Jpeg2000 file, resulting in an instant loading of the image in Monteverdi. Since the wheight of these extra files is ususally of a few megaoctets, it is recommended to keep this option checked unless one has a very good reason not to. Now that the Pleiades image is loaded in Monteverdi, it appears in the main Monteverdi window, as shown in figure 4.2, page 168.