This is because they no longer exist as separate classes. One of the first things to notice is that if you change to color to red (or any other color) for the two classes that you merged together, that they are now "No Data" and the red color does not appear on the image. Open a raster attribute table for each viewer by going to Raster > Attributes from the menu of each. In one Viewer open the image Unsupervised Classification image and in the other viewer open the Supervised Classification image. Hit OK when the classification is finished.ĥ. Hit OK and wait for the image to be classified. Don't worry about what they mean for right now. Fill in the Decision Rules section as shown above. When you are entering the "Input Signature File" by sure that you enter the edited Signature file, not the original signature file from the Unsupervised Classification. Remember, the "Classified File" will be the output file for the Supervised Classification and you can name it whatever you want. The following will appear.Įnter fields as they are in the above example table. Click on the Classify button again and select Supervised Classification.
HOW TO OPEN SIG FILE IN ERDAS HOW TO
You will now learn how to perform a Supervised Classification using the edited Signature File. Save the new Signature File and close the Signature Editor table.Ĥ.
With the two merged classes still selected, go to Edit > Delete to get rid them. Notice that a new class containing the data that you merged has been added to the last row in your table. In this example we will be merging classes 2 and 3 that were generated from an unsupervised classification into nine total classes. Hold down the shift key and then click on the other class(es) being merged.
To do this, click on the row of one of the Class #'s that you want to merge. To merge two classes, you first need to select them from the table. You may want to do this after you go into the field and decide that two of the classes that were separately grouped during the unsupervised classification are really the same thing (i.e. This part of the exercise will show you how to merge two classes. sig file is open, you may begin to edit it. The classes that you see here are those that were generated by the unsupervised classification and are based on spectral properties.ģ. You should now get values in your Signature Editor table. sig file that you named in your unsupervised classification. Go to the File menu in the Signature Editor window and open the.
Select Signature Editor from the menu and a Signature Editor table will appear. Begin by opening ERDAS from your Start Menu: Start > Programs > ERDAS IMAGINE Click on the Classifer button located in the main menu bar. This exercise will show you how to edit the signature file created from an Unsupervised Classification, perform a Supervised Classification, and check your data for accuracy by using Accuracy Assessment in ERDAS.Ģ.
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