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GDALADDO(1) GDAL GDALADDO(1)

NAME
gdaladdo - Builds or rebuilds overview images.

DESCRIPTION
The gdaladdo utility can be used to build or rebuild overview images
for most supported file formats with one of several downsampling algo-
rithms.

--help Show this help message and exit

--help-general
Gives a brief usage message for the generic GDAL commandline op-
tions and exit.

-r {nearest|average|rms|gauss|bilinear|cubic|cubicspline|lanczos|aver-
age_magphase|mode}
Select a resampling algorithm. The default is nearest, which is
generally not appropriate if sub-pixel accuracy is desired.

Starting with GDAL 3.9, 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 pix-
els. Starting with GDAL 3.1, this is a weighted average taking
into account properly the weight of source pixels not contribut-
ing fully to the target pixel.

rms computes the root mean squared / quadratic mean of all
non-NODATA contributing pixels (GDAL >= 3.3)

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 re-
sampling Gaussian kernel is selected.

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.

average_magphase averages complex data in mag/phase space.

mode selects the value which appears most often of all the sam-
pled points.

-b <band>
Select an input band band for overview generation. Band number-
ing starts from 1. Multiple -b switches may be used to select a
set of input bands to generate overviews.

-ro open the dataset in read-only mode, in order to generate exter-
nal overview (for GeoTIFF especially).

-clean remove all overviews.

-oo <NAME>=<VALUE>
Dataset open option (format specific)

-minsize <val>
Maximum width or height of the smallest overview level. Only
taken into account if explicit levels are not specified. De-
faults to 256.

Added in version 2.3.

--partial-refresh-from-source-timestamp
Added in version 3.8.

This option performs a partial refresh of existing overviews,
when <filename> is a VRT 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 Example 7.

--partial-refresh-from-projwin <ulx> <uly> <lrx> <lry>
Added in version 3.8.

This option performs a partial refresh of existing overviews, in
the region of interest specified by georeference coordinates
where <ulx> is the X value of the upper left corner, <uly> is
the Y value of the upper left corner, <lrx> is the X value of
the lower right corner and <lry> is the Y value of the lower
right corner. By default all existing overview levels will be
refreshed, unless explicit levels are specified.

--partial-refresh-from-source-extent <filename1>[,<filenameN>]...
Added in version 3.8.

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 refer-
ence 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 8.

<filename>
The file to build overviews for (or whose overviews must be re-
moved).

<levels>
A list of integral overview levels to build. Ignored with -clean
option.

Added in version 2.3: Levels are no longer required to build
overviews. In which case, appropriate overview power-of-two
factors will be selected until the smallest overview is smaller
than the value of the -minsize switch.

Starting with GDAL 3.9, if there are already existing overviews,
the corresponding levels will be used to refresh them if no ex-
plicit levels are specified.

gdaladdo will honour properly NODATA_VALUES tuples (special dataset
metadata) so that only a given RGB triplet (in case of a RGB image)
will be considered as the nodata value and not each value of the
triplet independently per band.

Selecting a level value like 2 causes an overview level that is 1/2 the
resolution (in each dimension) of the base layer to be computed. If
the file has existing overview levels at a level selected, those levels
will be recomputed and rewritten in place.

For internal GeoTIFF overviews (or external overviews in GeoTIFF for-
mat), note that -clean does not shrink the file. A later run of gdal-
addo with overview levels will cause the file to be expanded, rather
than reusing the space of the previously deleted overviews. If you just
want to change the resampling method on a file that already has
overviews computed, you don't need to clean the existing overviews.

Some format drivers do not support overviews at all. Many format dri-
vers store overviews in a secondary file with the extension .ovr that
is actually in TIFF format. By default, the GeoTIFF driver stores
overviews internally to the file operated on (if it is writable), un-
less the -ro flag is specified.

Most drivers also support an alternate overview format using Erdas
Imagine format. To trigger this use the USE_RRD=YES configuration op-
tion (Example 5). This will place the overviews in an associated .aux
file suitable for direct use with Imagine or ArcGIS as well as GDAL ap-
plications. (e.g. --config USE_RRD YES)

EXTERNAL OVERVIEWS IN GEOTIFF FORMAT
External overviews created in TIFF format may be compressed using the
COMPRESS_OVERVIEW configuration option. All compression methods, sup-
ported by the GeoTIFF driver, are available here. (e.g. --config COM-
PRESS_OVERVIEW DEFLATE). The photometric interpretation can be set
with the PHOTOMETRIC_OVERVIEW =RGB/YCBCR/... configuration option, and
the interleaving with the INTERLEAVE_OVERVIEW =PIXEL/BAND configuration
option.

Since GDAL 3.6, COMPRESS_OVERVIEW and INTERLEAVE_OVERVIEW are honoured
when creating internal overviews of TIFF files.

For JPEG compressed external and internal overviews, the JPEG quality
can be set with --config JPEG_QUALITY_OVERVIEW value.

For WEBP compressed external and internal overviews, the WEBP quality
level can be set with --config WEBP_LEVEL_OVERVIEW value. If not set,
will default to 75.

For WEBP compressed external and internal overviews, the WEBP loss-
less/lossy switch can be set with --config WEBP_LOSSLESS_OVERVIEW
value. If not set, will default to NO (lossy). Added in GDAL 3.6.0

For LERC compressed external and internal overviews, the max error
threshold can be set with --config MAX_Z_ERROR_OVERVIEW value. If not
set, will default to 0 (lossless). Added in GDAL 3.4.1

For DEFLATE or LERC_DEFLATE compressed external and internal overviews,
the compression level can be set with --config ZLEVEL_OVERVIEW value.
If not set, will default to 6. Added in GDAL 3.4.1

For ZSTD or LERC_ZSTD compressed external and internal overviews, the
compression level can be set with --config ZSTD_LEVEL_OVERVIEW value.
If not set, will default to 9. Added in GDAL 3.4.1

For JPEG-XL compressed external and internal overviews, the following
settings can be set since GDAL 3.9.0:

• Whether compression should be lossless with --config JXL_LOSS-
LESS_OVERVIEW YES|NO. Default is YES

• Level of effort with --config JXL_EFFORT_OVERVIEW value, with value
between 1(fast) and 9(flow). Default is 5

• Distance level for lossy compression with --config JXL_DIS-
TANCE_OVERVIEW value, with value: 0=mathematically lossless, 1.0=vi-
sually lossless, usual range [0.5,3]. Default is 1.0. Ignored if
JXL_LOSSLESS_OVERVIEW is YES

• Distance level for lossy compression of alpha channel with --config
JXL_ALPHA_DISTANCE_OVERVIEW value, with value: 0=mathematically loss-
less, 1.0=visually lossless, usual range [0.5,3]. Default is the same
value as JXL_DISTANCE_OVERVIEW. Ignored if JXL_LOSSLESS_OVERVIEW is
YES

For LZW, ZSTD or DEFLATE compressed external overviews, the predictor
value can be set with --config PREDICTOR_OVERVIEW 1|2|3.

To produce the smallest possible JPEG-In-TIFF overviews, you should
use:

--config COMPRESS_OVERVIEW JPEG --config PHOTOMETRIC_OVERVIEW YCBCR --config INTERLEAVE_OVERVIEW PIXEL

External overviews can be created in the BigTIFF format by using the
BIGTIFF_OVERVIEW configuration option: --config BIGTIFF_OVERVIEW
{IF_NEEDED|IF_SAFER|YES|NO}.

The default value is IF_SAFER starting with GDAL 2.3.0 (previously was
IF_NEEDED). The behavior of this option is exactly the same as the
BIGTIFF creation option documented in the GeoTIFF driver documentation.

• YES forces BigTIFF.

• NO forces classic TIFF.

• IF_NEEDED will only create a BigTIFF if it is clearly needed (uncom-
pressed, and overviews larger than 4GB).

• IF_SAFER will create BigTIFF if the resulting file might exceed 4GB.

Sparse GeoTIFF overview files (that is tiles which are omitted if all
their pixels are at the nodata value, when there's one, or at 0 other-
wise) can be obtained with --config SPARSE_OK_OVERVIEW ON. Added in
GDAL 3.4.1

See the documentation of the GTiff -- GeoTIFF File Format driver for
further explanations on all those options.

SETTING BLOCKSIZE IN GEOTIFF OVERVIEWS
--config GDAL_TIFF_OVR_BLOCKSIZE <size>

Example: --config GDAL_TIFF_OVR_BLOCKSIZE 256

Default value is 128, or starting with GDAL 3.1, if creating overviews
on a tiled GeoTIFF file, the tile size of the full resolution image.
Note: without this setting, the file can have the full resolution image
with a blocksize different from overviews blocksize.(e.g. full resolu-
tion image at blocksize 256, overviews at blocksize 128)

NODATA / SOURCE VALIDITY MASK HANDLING DURING RESAMPLING
Invalid values in source pixels, either identified through a nodata
value metadata set on the source band, a mask band, an alpha band will
not be used during resampling.

orphan

The details of how it is taken into account depends on the resampling
kernel:

• for nearest resampling, for each target pixel, one of the potential
contributing source pixels is selected (in an implementation specific
way). Its value is used as it, be it valid or invalid.

• for bilinear, cubic, cubicspline and lanczos, for each target pixel,
the weights of contributing source pixels is set to zero to ignore
them when they are masked. There is an extra specificity for cubic:
given that some of the weights in the kernel are negative, such
strategy could lead to strong overshoot/undershoot when there is an
alternance of valid and invalid pixels. Consequently, if any of the
horizontal or vertical direction, if the maximum number of valid
source pixels in each dimension is less than the radius of the resam-
pling kernel, the target pixel is considered as nodata.

• for the other resampling methods, source pixels contributing to the
target pixel are ignored if masked. Only the valid ones are taken
into account. If there are none, the target pixel is considered as
nodata.

MULTITHREADING
Added in version 3.2.

The GDAL_NUM_THREADS configuration option can be set to ALL_CPUS or a
integer value to specify the number of threads to use for overview com-
putation.

C API
Functionality of this utility can be done from C with
GDALBuildOverviews().

EXAMPLES
Example 1: Create overviews, embedded in the supplied TIFF file, with auto-
matic computation of levels
gdaladdo -r average abc.tif

Example 2: Create overviews, embedded in the supplied TIFF file
gdaladdo -r average abc.tif 2 4 8 16

Example 3: Create an external compressed GeoTIFF overview file from the ER-
DAS .IMG file
gdaladdo -ro --config COMPRESS_OVERVIEW DEFLATE erdas.img 2 4 8 16

Example 4: Create an external JPEG-compressed GeoTIFF overview file from a
3-band RGB dataset
If the dataset is a writable GeoTIFF, you also need to add the -ro op-
tion to force the generation of external overview.

gdaladdo --config COMPRESS_OVERVIEW JPEG --config PHOTOMETRIC_OVERVIEW YCBCR
--config INTERLEAVE_OVERVIEW PIXEL rgb_dataset.ext 2 4 8 16

Example 5: Create Erdas Imagine format overviews for the indicated JPEG
file
gdaladdo --config USE_RRD YES airphoto.jpg 3 9 27 81

Example 6: Create overviews for a specific subdataset
For example, one of potentially many raster layers in a GeoPackage (the
"filename" parameter must be driver prefix, filename and subdataset
name, like e.g. shown by gdalinfo):

gdaladdo GPKG:file.gpkg:layer

Example 7: Refresh overviews of a VRT file
This is needed when for sources have been modified after the .vrt.ovr
generation:

gdalbuildvrt my.vrt tile1.tif tile2.tif # create VRT
gdaladdo -r cubic my.vrt # initial overview generation
touch tile1.tif # simulate update of one of the source tiles
gdaladdo --partial-refresh-from-source-timestamp -r cubic my.vrt # refresh overviews

Example 8: Refresh overviews of a TIFF file
gdalwarp -overwrite tile1.tif tile2.tif mosaic.tif # create mosaic
gdaladdo -r cubic mosaic.tif # initial overview generation
touch tile1.tif # simulate update of one of the source tiles
gdalwarp tile1.tif mosaic.tif # update mosaic
gdaladdo --partial-refresh-from-source-extent tile1.tif -r cubic mosaic.tif # refresh overviews

AUTHOR
Frank Warmerdam <warmerdam@pobox.com>, Silke Reimer <silke@inteva-
tion.de>

Jul 12, 2025 GDALADDO(1)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=gdaladdo&sektion=1&manpath=FreeBSD+Ports+15.0>

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