Recomputing footprints to remove unwanted pixel data

The Recompute Footprint By Radiometry option redefines the shape of the footprint based on a pixel value range. This option is generally used to redefine footprints so that they exclude border areas, which do not define valid data. Such border areas that are mostly in black or white occur on rotated raster datasets or scenes that were rectified, but not mosaicked. The footprint is redefined based on the radiometry of the border pixel value. This computation is performed at the image service definition level. You can use the Recompute Footprint By Radiometry option to remove unwanted pixels, which is much more efficient than using transparency. For NoData areas with different colors other than black and white, you will have to apply a Classify Pixel process, then use the Recompute Footprint By Radiometry option to remove the NoData areas. See About using transparency in an image service definition on how to remove such NoData areas.

The Recompute Footprint By Radiometry dialog box has two tabs: General and Advanced. The values set on the General tab will redefine the advanced parameters that are used by this process. The following Image type and Image compression options are provided on the General tab.

The image type options define various types of datasets that sometimes have NoData borders. The Image type options are as follows:

The image compression options are as follows:

The values you set in the General tab will automatically update the appropriate values in the Advanced tab. You can also review and redefine the values to improve the results. The following parameters can be set using the Advanced tab:

步骤:
  1. Open an existing image service definition or use one that is already open in ArcMap.
  2. Optionally, select the raster to be processed.
  3. Right-click the Footprint layer in the table of contents and click Recompute Footprint > By Radiometry.

    The Recompute Footprint By Radiometry dialog box is displayed with default values for each of the parameters.

  4. Click the Image type drop-down arrow and click an option.
  5. Click the Image compression drop-down arrow and click to select Noncompressed imagery or Lossy compressed imagery.
  6. Optionally, click the Advanced tab and make changes to the parameters.
  7. Click OK.
注注:

This operation is performed on the data at the image service definition level. You can also recompute the footprint of an image service after applying processes. For example, If the NoData value does not conform to black or white, you may need to apply the Classify Pixel process on an image service before recomputing the footprints, which can be removed later.

注注:

For images with alpha channel bands, you can use the Recompute Footprint By Radiometry option to display alpha channel bands as NoData.

提示提示:

The Shrink Footprint feature can be used to reduce the footprints to a greater extent.


7/10/2012