Using gvSIG's Geographic Transformation on a raster file

gvSIG has a Photoshop-like tool that can be used to perform geometric transformations on raster files. Transformations such as translation, rotation, scaling, and skewing can be applied interactively to a raster file. The example below illustrates the Geographic Transformation command.

Start the Transformation command

1. Run gvSIG OADE 2010. Load and display a raster file.
   
   
   
   
2. In the toolbar, locate the Geographic transformation icon as shown below.
   
   
   
   
3. Then locate and click the Transformation icon as shown below.
   
    
   
   The Transformation dialog box appears.
   
   
   Note: the raster layer can be transformed either by changing the values in the Transformation dialog box or by graphically adjusting the image in the map view.
   
4. In the Transformation dialog box, click the Center raster layer in view icon.
   
   The raster layer is scaled, moved and centered in the map view.
   
   
   Moving the raster image

1. In the map view. move the cursor to the middle of the raster image.
   
   The cursor becomes a hand.
   
2. Press down the mouse left button and drag the image.
   
   The raster image is moved to another location.
   
   

Skew the image in the Y-axis direction

1. Move the cursor to the vertical sides of the raster image.
   
   The cursor changes to an arrow with a Y label.
   
2. Press down the left mouse button and drag the image along the Y axis.
   
   The image is skewed in the Y-axis direction.
   
   

Skew the raster image in the X-axis direction

1. Move the cursor to the horizontal sides of the raster image.
   
   The cursor changes to an arrow with the label X.
   
2. Press down the left mouse button and drag the image in the X-axis direction.
   
   The raster image becomes skewed in the X-axis direction.
   

Rotate the raster image

1. Move the cursor to any corners of the raster image.
   
   The cursor changes to a rounded arrow.
   
2. Press down the left mouse button and drag the image around the corner.
   
   The raster image is rotated.
   

Resize the raster image

1. Move the cursor along the sides and corners of the raster image.
   
   The cursor changes to a two-headed arrow.
   
2. Press down the left mouse button and drag the image inwards or outwards.
   
   The raster image is resized.
   

Save the transformation

1. In the Transformation dialog box, click the Save transformation icon.
   
   The message appears.
   
   
   
2. Click Yes.
   
   The adjustments are saved.