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How to use the Clip tool for Raster images in MapInfo Pro

Products affected: MapInfo Pro™
Clipping of a raster grid is a process of creating a spatial subset of the input raster dataset. Using the clip tool, you can extract a portion of the input data based on user defined extent(s). The output will consist of cells that intersect the extent(s).

To access Raster Clipping functionality, go to Raster > Operations > Raster Operations > Clip.
This will load the Clip dialog referenced in the examples below.

The area to be clipped can be specified by one of the following:
  1. Rectangle - Define the extents (Min X, Min Y, Max X, and Max Y) on the input grid to clip a rectangular region inside or outside the clip extents.
  2. Region(Polygon) - Import a tab file of region(s) and clip the grid against the regions defined in the tab file.
  3. Map Extent - Retain the portion of the area which is visible in the map window.
  4. Raster - Clip a raster using another raster as the clip mask. The overlapping area of the raster defines the clip region.


The extent coordinates must be in the same projection system as the input grid coordinates.



Clip using Rectangle
In this clip method, the rectangular bounds define the clip area. You can either clip to the clip region or clip outside the extent. An example of this is illustrated below.

The following denotes an input raster with the clip area defined in red.

User-added image



User-added image


User-added image



In this clip method, a TAB file containing shape(s) define the clip region(s) of the input grid. The shapes can be a polygon, an ellipse, or a rounded rectangle.

Using the same input raster as above as example, the TAB file will clip the raster according to the defined shapes. An example of a TAB file containing shapes is shown below:

User-added image
The following table shows the clip results after clipping inside and outside the extent region.

Retain Inside

User-added image
Retain Outside

User-added image
Clip using Map Extent
In this clip method, the map extent of the input grid file defines the clip region of the input grid. The portion of the main grid which lies outside the viewing region of the region to be clipped is removed, as defined by the clip action.

 

Exploring the Clip Dialog Box

The Clip dialog box enables users to clip out a part of an image or raster grid. One way is to clip using a rectangular shape according to the extents defined. The second way is to clip the raster to the shape of a single or multiple input polygons.

Input File

Select an input raster you want to clip from the drop-down list.

Select Fields, Bands

If the input raster has multiple fields and bands, the Select Fields, Bands option allows users to choose either All Fields All Bands or a particular field for the processing.

Select a specific field from the drop-down list, users can then choose the desired bands from that field. One can not select bands from different fields, because only one field can be selected at a time. Click the radio button against the field or check-box against the band that one wants to select.
By default All Fields All Bands option is selected for you.

Clip Options

The Clip Options sections consists of the following, as shown in the image below:

  • Action - The clipping action removes a portion of the main grid that lies outside or inside of a clipping region. There are two clipping actions:
    1. Retain Inside Region - The imagery inside the extent will be retained.
    2. Retain Outside Region - The imagery outside the extent will be retained.
  • Clip Region - There are four clipping options:
    1. Rectangle - Define the extents (Min X, Min Y, Max X, and Max Y) on the input grid to clip a rectangular region inside or outside the clip extents.
    2. Region(Polygon) - Import a tab file of region(s) and clip the grid against the regions defined in the tab file.
    3. Map Extent - Retain the portion of the area which is visible in the map window.
    4. Raster - Clip a raster using another raster as the clip mask. The overlapping area of the raster defines the clip region.


Output File

In the Output File box enter the desired name for the output file. Click  to browse to the location in your computer to save the output file and select the required output file format.

Click Output Settings to specify the following. The values in Output Settings are controlled by the Raster Preferences dialog; however, users can override those settings here.

  • Display Output File - Select the check-box, if one wants to open the output file in the Map window on completion of the operation. Users can configure to make this the default behavior from the Raster Preferences dialog.
  • Compression Settings - If the output file format is MRR or TIFF, the Compression Settings drop-down will appear. The available options are listed below.

    The Data Balanced allows users to achieve a balance between speed of operation and file size. The system selects the best combination of speed and space automatically. With the other two options Data Speed and Data Space, users can choose between speed and space. Choose Advanced option to set the advanced compression options such as compression method, level, and encoding type. For details, on Advanced option, see Compression Settings.

    • Data Balanced
    • Data Speed
    • Data Space
    • Advanced
  • Compression- Select a suitable compression method and level for the data. For more information on compression, see Compression methods.
  • Encoding Type - Select a suitable Encoding Type for the data from the list. It enables one to compress the data when saving a raster to MRR format. Encoding Type is enabled only when the raster field type is Continuous and the compression method is lossless such as ZIP, LZMA or LZ4. The drop-down list contains the following:
    • None - No encoding.
    • Previous Column Linear - Performs linear estimation of the value from previous two columns.
    • Previous Column Value - Predicts the value from previous column.
 
UPDATED:  October 15, 2018