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.TH "GDAL-RASTER-OVERVIEW-REFRESH" "1" "Aug 18, 2026" "" "GDAL"
.SH NAME
gdal-raster-overview-refresh \- Refresh overviews
.sp
Added in version 3.12.

.SH SYNOPSIS
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.EX
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]
.EE
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.SH DESCRIPTION
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\fBgdal raster overview refresh\fP 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.
.SH PROGRAM-SPECIFIC OPTIONS
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.B \-\-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.
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\(aqx\(aq is longitude values for geographic CRS and easting for projected CRS.
\(aqy\(aq is latitude values for geographic CRS and northing for projected CRS.
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.B \-\-dataset <DATASET>
Dataset name, to be updated in\-place by default (unless \fI\%\-\-external\fP is specified). Required.
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.B \-\-external
Refresh external \fB\&.ovr\fP overviews.
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.B \-\-levels <level1,level2,...>
A list of overview levels to build. Each overview level must be an integer
value greater or equal to 2.
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If not specified all existing overviews are refreshed.
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.B \-\-like <filename1>[,<filenameN>]...
This option performs a partial refresh of existing overviews, in the region
of interest specified by one or several filenames (names separated by comma).
Note that the filenames are only used to determine 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 \fI\%Example 2\fP\&.
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.B \-r, \-\-resampling {nearest|average|cubic|cubicspline|lanczos|bilinear|gauss|average_magphase|rms|mode}
Select a resampling algorithm. The default is \fBnearest\fP, which is generally not
appropriate if sub\-pixel accuracy is desired.
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When refreshing existing TIFF overviews, the previously
used method, as noted in the RESAMPLING metadata item of the overview, will
be used if \fI\%\-r\fP is not specified.
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The available methods are:
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\fBnearest\fP applies a nearest neighbour (simple sampling) resampler.
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\fBaverage\fP 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.
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\fBbilinear\fP applies a bilinear convolution kernel.
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\fBcubic\fP applies a cubic convolution kernel.
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\fBcubicspline\fP applies a B\-Spline convolution kernel.
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\fBlanczos\fP applies a Lanczos windowed sinc convolution kernel.
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\fBgauss\fP 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.
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\fBaverage_magphase\fP averages complex data in mag/phase space.
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\fBrms\fP computes the root mean squared / quadratic mean of all non\-NODATA contributing pixels
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\fBmode\fP selects the value which appears most often of all the sampled points.
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.B \-\-use\-source\-timestamp
This option performs a partial refresh of existing overviews of a
\fI\%VRT \-\- GDAL Virtual Format\fP or \fI\%GTI \-\- GDAL Raster Tile Index\fP 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 external overview of the VRT.
By default all existing overview levels will be refreshed, unless explicit
levels are specified. See \fI\%Example 1\fP\&.
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.SH STANDARD OPTIONS
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.B \-\-oo, \-\-open\-option <NAME>=<VALUE>
Dataset open option (format specific).
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May be repeated.
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.SH RETURN STATUS CODE
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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 successful
execution).
.SH EXAMPLES
.SS Example 1: Refresh external overviews of a VRT file using timestamp of source files
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This is needed when for sources have been modified after the .vrt.ovr generation:
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.EX
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 \e
                          \-\-use\-source\-timestamp my.vrt     # refresh overviews
.EE
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.SS Example 2: Refresh (internal) overviews of a TIFF file
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.EX
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
.EE
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.SH AUTHOR
Even Rouault <even.rouault@spatialys.com>
.SH COPYRIGHT
1998-2026
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