To Execute the Training

This page describes the procedures of the "Training" window used to edit (create, change, remove) the samples from a classified image either by "pixel" or by region ( make the segmentation previously).


Executing the Training:

  • after clicking on Training... in the "Classification" window, the user has access to the window to edit the classified samples;
  • The themes can be created directly in the Training window or can be imported from a Thematic Information Layer, the procedures for getting the themes are described below;
  • After getting the themes it is possible to edit the samples;
  • select the sample Type: Acquisition or Test. The "Training" interface allows two types of samples acquisition: Acquisition or Test.
  • The samples obtained in the Acquisition mode are used in the classification process and, the samples obtained by the Test mode are used only for studying. Generally the test samples are imperfect acquisitions that are stored for possible future use. The Acquisition mode is the "default"; if the user wants to use some of these samples as Test, select them before the acquisition process or change them later;
  • the samples can be obtained editing the contours (Polygon or Rectangle modes), or use the contours in a segmented image, see the procedures below.

Creating Themes:

  • in the "Training" window, give the theme's Name (for instance, Forest, Water etc);
  • click on Color... and select a color for the theme being created;
  • click on Create. Notice that the theme is presented in the Themes list.

Importing Themes:

  • in the "Training" window, click on “Import...”;
  • in the "Categories and Infolayers" window select the category and the IL that has the polygons to be imported;
  • click on “Apply”, in the “Categories and Infolayers” window;
  • The polygons from the selected IL are imported as samples and the classes that the polygons belong to are imported as themes;
  • click on Save to store the imported samples and themes.

Exporting Themes:

Option to export the themes to a thematic IL.

  • Select the thematic category created previously;
  • type in the output IL name;
  • select the sample type that will be exported (test, acquisition or both);
  • click on Export.

Note: Each theme is created as a thematic class, and the samples become polygons of this class. In case there is a class previously created with the same name, the samples will be associated to the previously created class, and the class is not "recreated".


Getting samples in the rectangle mode:

  • click on Rectangle and activate the Zoom Cursor ( ) in the main menu;
  • click over an image to define the sample upper left corner, drag diagonally and click again to define the sample lower right corner;
  • click on Get. Notice that the sample appears in the list with a number and its type (Acquisition or Test);
  • repeat the steps above to create other themes and other samples. Try to include inside each sample just the pixels corresponding to the same theme. Get the maximum number of samples possible for the same theme, the larger the number of samples, well selected, the better the precision for the theme classification;
  • click on Save to store the samples and themes defined.


Acquiring samples in the polygon mode:

  • click on Polygon and disable the Area Cursor in case it is active. Notice that the Polygon Editing buttons become active, and, by default the Closed Line option (Create CL) is active;
  • click over the image to initiate a polygon. Each mouse click defines a polygon vertex;
  • click the mouse right button (RB) to close the polygon (for more details see Create Closed Lines in the editing options);
  • click on Get. Notice that the sample appears in the list with its number and its type (Acquisition or Test);
  • repeat the step above to create other themes or other samples. Try to include inside the samples just the pixels corresponding to the same theme. Get the maximum number of samples possible for the same theme, the larger the number of samples, well selected, the better the precision for the theme classification;
  • click on Save to store the samples and themes defined.

NOTE: Before acquiring the polygon sample the user can make small adjustments in the polygon contour. Use the Add point, Move point and Remove point tools (see more at vector editing details). Once a sample is acquired it is not possible to edit it, the only option is to remove it, if desired.


Acquiring samples from a segmented image:

  • after having executed the segmentation, having defined the context file (by regions) and having executed the Regions Extraction, the user can use the segmented image as a sample contour. Notice that in this case, besides the Polygon and Rectangle buttons, also the Region button is enabled;
  • select the segmented image (also called labeled image in the "Control Panel") an show it in the active window. It is suggested to use the original images (monochromatic or colored composition) as a background for the segmented image;
  • click over a region in the window;
  • click on Get. Notice that the sample appears in the list with its number and its type (Acquisition or Test);
  • repeat the steps above to create other themes or samples;
  • click on Save to store the samples and themes defined.


NOTES:

1- To change the theme color or name click  on the list, change the color and/or name and click on Change so the changes will take effect.

2- To remove a theme or sample from the list, select a theme or sample and click on Delete to remove it. Be careful when deleting themes, because all samples associated to it will also be removed;

3- Click on View to draw in the active window the contour of all samples of the selected theme, or just the selected sample. The sample contour will be displayed using the color selected for the theme.

4- To change the sample type (Acquisition or Test), click   on the list, change the type and click on Change so the changes will take effect;

5- Use the Zoom tool (Zoom Cursor ) to define the samples with higher precision.

6- After getting the samples, it is recommended to analyze them, because in this way it is possible to change its type (from Acquisition to Test) or even remove it, if it is not representative of the process.

7- After importing themes and samples, it is possible to edit them normally as if they had been defined in the interface.

8- If desired Save the training file to use it in the Neural Networks Training, click on the Exporting a Neural Networks File (SNNS) option. In this way the file will be saved in two ways: with a ".pat" extension and normal. Read more about NEURAL NETWORKS TRAINING

If no more samples will be obtained, then the user can close the "Training" window. Do not forget to Save before closing it.



Image Classification