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GDAL-RASTER-OVERVIEW-REFRESH(1)       GDAL	 GDAL-RASTER-OVERVIEW-REFRESH(1)

NAME
     gdal-raster-overview-refresh - Refresh overviews

     Added in version 3.12.

SYNOPSIS
	Usage: gdal raster overview refresh [OPTIONS] <INPUT>

	Refresh overviews.

	Positional arguments:
	  -i, --dataset, --input <INPUT>     Dataset (to be updated in-place, unless --external) [required]

	Common Options:
	  -h, --help			     Display help message and exit
	  --json-usage			     Display usage as JSON document and exit
	  --config <KEY>=<VALUE>	     Configuration option [may be repeated]
	  -q, --quiet			     Quiet mode (no progress bar or warning message) [not available in pipelines]

	Options:
	  --external			     Refresh external overviews
	  -r, --resampling <RESAMPLING>      Resampling method. RESAMPLING=nearest|average|cubic|cubicspline|lanczos|bilinear|gauss|average_magphase|rms|mode
	  --levels <LEVELS>		     Levels / decimation factors [may be repeated]
	  --bbox <BBOX> 		     Bounding box to refresh
					     Mutually exclusive with --like, --use-source-timestamp
	  --like <LIKE> 		     Use extent of dataset(s) [may be repeated]
					     Mutually exclusive with --bbox, --use-source-timestamp
	  --use-source-timestamp	     Use timestamp of VRT or GTI sources as refresh criterion
					     Mutually exclusive with --bbox, --like

	Advanced Options:
	  --oo, --open-option <KEY>=<VALUE>  Open options [may be repeated]

DESCRIPTION
     gdal raster overview refresh can be used to refresh existing overviews of a
     dataset.	By  default all overviews are refreshed, but it is also possible
     to restrict the refreshed overviews by level and/or extent.

PROGRAM-SPECIFIC OPTIONS
     --bbox <xmin>,<ymin>,<xmax>,ymax>
	    This option performs a partial refresh of existing overviews, in the
	    region of interest specified by georeferenced  coordinates,  in  CRS
	    units.

	    'x' is longitude values for geographic CRS and easting for projected
	    CRS.   'y'	is  latitude  values for geographic CRS and northing for
	    projected CRS.

     --dataset <DATASET>
	    Dataset name, to be updated in-place by default  (unless  --external
	    is specified). Required.

     --external
	    Refresh external .ovr overviews.

     --levels <level1,level2,...>
	    A  list  of overview levels to build. Each overview level must be an
	    integer value greater or equal to 2.

	    If not specified all existing overviews are refreshed.

     --like <filename1>[,<filenameN>]...
	    This option performs a partial refresh of existing overviews, in the
	    region of interest specified by one or several filenames (names sep-
	    arated by comma).  Note that the filenames are only used  to  deter-
	    mine the regions of interest to refresh. The reference source pixels
	    are  the  one of the main dataset.	By default all existing overview
	    levels will be refreshed, unless explicit levels are specified.  See
	    Example 2.

     -r, --resampling {nearest|average|cubic|cubicspline|lanczos|bilin-
     ear|gauss|average_magphase|rms|mode}
	    Select a resampling algorithm. The default is nearest, which is gen-
	    erally not appropriate if sub-pixel accuracy is desired.

	    When refreshing existing TIFF overviews, the previously used method,
	    as	noted  in  the RESAMPLING metadata item of the overview, will be
	    used if -r is not specified.

	    The available methods are:

	    nearest applies a nearest neighbour (simple sampling) resampler.

	    average computes the average of all non-NODATA contributing  pixels.
	    This  is  a weighted average taking into account properly the weight
	    of source pixels not contributing fully to the target pixel.

	    bilinear applies a bilinear convolution kernel.

	    cubic applies a cubic convolution kernel.

	    cubicspline applies a B-Spline convolution kernel.

	    lanczos applies a Lanczos windowed sinc convolution kernel.

	    gauss applies a Gaussian kernel before computing the overview, which
	    can lead to better results than simple  averaging  in  e.g	case  of
	    sharp  edges with high contrast or noisy patterns. The advised level
	    values should be 2, 4, 8, ...  so that  a  3x3  resampling	Gaussian
	    kernel is selected.

	    average_magphase averages complex data in mag/phase space.

	    rms  computes  the root mean squared / quadratic mean of all non-NO-
	    DATA contributing pixels

	    mode selects the value which appears most often of all  the  sampled
	    points.

     --use-source-timestamp
	    This  option  performs  a partial refresh of existing overviews of a
	    VRT -- GDAL Virtual Format or GTI -- GDAL  Raster  Tile  Index  file
	    with  an external overview.  It checks the modification timestamp of
	    all the sources of the VRT and regenerate  the  overview  for  areas
	    corresponding to sources whose timestamp is more recent than the ex-
	    ternal overview of the VRT.  By default all existing overview levels
	    will be refreshed, unless explicit levels are specified. See Example
	    1.

STANDARD OPTIONS
     --oo, --open-option <NAME>=<VALUE>
	    Dataset open option (format specific).

	    May be repeated.

RETURN STATUS CODE
     The  program returns status code 0 in case of success, and non-zero in case
     of error (non-blocking errors emitted as warnings are considered as a  suc-
     cessful execution).

EXAMPLES
   Example 1: Refresh external overviews of a VRT file using timestamp of source
     files
     This  is needed when for sources have been modified after the .vrt.ovr gen-
     eration:

	gdal raster mosaic tile1.tif tile2.tif my.vrt		    # create VRT
	gdal raster overview add --external -r cubic my.vrt	    # initial overview generation
	touch tile1.tif 					    # simulate update of one of the source tiles
	gdal raster overview refresh --external -r cubic \
				  --use-source-timestamp my.vrt     # refresh overviews

   Example 2: Refresh (internal) overviews of a TIFF file
	gdal raster mosaic tile1.tif tile2.tif mosaic.tif	# create mosaic
	gdal raster overview add -r cubic mosaic.tif		# initial overview generation
	gdalwarp tile1_modif.tif mosaic.tif			# update mosaic
	gdal raster overview refresh --like=tile1.tif my.tif	# refresh overviews

AUTHOR
     Even Rouault <even.rouault@spatialys.com>

COPYRIGHT
     1998-2026

				  Jun 05, 2026	 GDAL-RASTER-OVERVIEW-REFRESH(1)

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