1gdaladdo(1)                 General Commands Manual                gdaladdo(1)
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NAME

6       gdaladdoBuilds or rebuilds overview images.
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SYNOPSIS

9       gdaladdo [-r {nearest,average,gauss,cubic,cubicspline,lanczos,average_mp,average_magphase,mode}]
10                [-b band]* [-minsize val]
11                [-ro] [-clean] [-oo NAME=VALUE]* [--help-general] filename [levels]
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DESCRIPTION

14       The gdaladdo utility can be used to build or rebuild overview images
15       for most supported file formats with one of several downsampling
16       algorithms.
17
18       -r {nearest
19       (default),average,gauss,cubic,cubicspline,lanczos,average_mp,average_magphase,mode}:
20           Select a resampling algorithm.
21
22       -b band:
23           (available from GDAL 1.10) Select an input band band for overview
24           generation. Band numbering starts from 1. Multiple -b switches may
25           be used to select a set of input bands to generate overviews.
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27       -ro:
28           (available from GDAL 1.6.0) open the dataset in read-only mode, in
29           order to generate external overview (for GeoTIFF especially).
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31       -clean:
32           (available from GDAL 1.7.0) remove all overviews.
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34       -oo NAME=VALUE:
35           (starting with GDAL 2.0) Dataset open option (format specific)
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37       -minsize val:
38           (starting with GDAL 2.3) Maximum width or height of the smallest
39           overview level. Only taken into account if explicit levels are not
40           specified. Defaults to 256.
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42       filename:
43           The file to build overviews for (or whose overviews must be
44           removed).
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46       levels:
47           A list of integral overview levels to build. Ignored with -clean
48           option. Starting with GDAL 2.3, levels are no longer required to
49           build overviews. In which case, appropriate overview power-of-two
50           factors will be selected until the smallest overview is smaller
51           than the value of the -minsize switch.
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53       Mode (available from GDAL 1.6.0) selects the value which appears most
54       often of all the sampled points. average_mp is unsuitable for use.
55       Average_magphase averages complex data in mag/phase space. Nearest and
56       average are applicable to normal image data. Nearest applies a nearest
57       neighbour (simple sampling) resampler, while average computes the
58       average of all non-NODATA contributing pixels. Cubic resampling
59       (available from GDAL 1.7.0) applies a cubic convolution kernel. Gauss
60       resampling (available from GDAL 1.6.0) applies a Gaussian kernel before
61       computing the overview, which can lead to better results than simple
62       averaging in e.g case of sharp edges with high contrast or noisy
63       patterns. The advised level values should be 2, 4, 8, ... so that a 3x3
64       resampling Gaussian kernel is selected. CubicSpline resampling
65       (available from GDAL 2.0) applies a B-Spline convolution kernel.
66       Lanczos resampling (available from GDAL 2.0) applies a Lanczos windowed
67       sinc convolution kernel.
68
69       gdaladdo will honour properly NODATA_VALUES tuples (special dataset
70       metadata) so that only a given RGB triplet (in case of a RGB image)
71       will be considered as the nodata value and not each value of the
72       triplet independently per band.
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74       Selecting a level value like 2 causes an overview level that is 1/2 the
75       resolution (in each dimension) of the base layer to be computed. If the
76       file has existing overview levels at a level selected, those levels
77       will be recomputed and rewritten in place.
78
79       For internal GeoTIFF overviews (or external overviews in GeoTIFF
80       format), note that -clean does not shrink the file. A later run of
81       gdaladdo with overview levels will cause the file to be expanded,
82       rather than reusing the space of the previously deleted overviews. If
83       you just want to change the resampling method on a file that already
84       has overviews computed, you don't need to clean the existing overviews.
85
86       Some format drivers do not support overviews at all. Many format
87       drivers store overviews in a secondary file with the extension .ovr
88       that is actually in TIFF format. By default, the GeoTIFF driver stores
89       overviews internally to the file operated on (if it is writable),
90       unless the -ro flag is specified.
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92       Most drivers also support an alternate overview format using Erdas
93       Imagine format. To trigger this use the USE_RRD=YES configuration
94       option. This will place the overviews in an associated .aux file
95       suitable for direct use with Imagine or ArcGIS as well as GDAL
96       applications. (e.g. --config USE_RRD YES)
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External overviews in GeoTIFF format

99       External overviews created in TIFF format may be compressed using the
100       COMPRESS_OVERVIEW configuration option. All compression methods,
101       supported by the GeoTIFF driver, are available here. (e.g. --config
102       COMPRESS_OVERVIEW DEFLATE). The photometric interpretation can be set
103       with --config PHOTOMETRIC_OVERVIEW {RGB,YCBCR,...}, and the
104       interleaving with --config INTERLEAVE_OVERVIEW {PIXEL|BAND}.
105
106       For JPEG compressed external overviews, the JPEG quality can be set
107       with '--config JPEG_QUALITY_OVERVIEW value' (GDAL 1.7.0 or later).
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109       For LZW or DEFLATE compressed external overviews, the predictor value
110       can be set with '--config PREDICTOR_OVERVIEW 1|2|3' (GDAL 1.8.0 or
111       later).
112
113       To produce the smallest possible JPEG-In-TIFF overviews, you should use
114       :
115
116       --config COMPRESS_OVERVIEW JPEG --config PHOTOMETRIC_OVERVIEW YCBCR --config INTERLEAVE_OVERVIEW PIXEL
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118
119       External overviews can be created in the BigTIFF format by using the
120       BIGTIFF_OVERVIEW configuration option : --config BIGTIFF_OVERVIEW
121       {IF_NEEDED|IF_SAFER|YES|NO}. The default value is IF_SAFER starting
122       with GDAL 2.3.0 (previously was IF_NEEDED). The behaviour of this
123       option is exactly the same as the BIGTIFF creation option documented in
124       the GeoTIFF driver documentation.
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126       · YES forces BigTIFF.
127       · NO forces classic TIFF.
128       · IF_NEEDED will only create a BigTIFF if it is clearly needed
129         (uncompressed, and overviews larger than 4GB).
130       · IF_SAFER will create BigTIFF if the resulting file might exceed 4GB.
131       See the documentation of the GeoTIFF driver for further explanations on
132       all those options.

C API

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

EXAMPLE

137       Create overviews, embedded in the supplied TIFF file, with automatic
138       computation of levels (GDAL 2.3 or later)
139       gdaladdo -r average abc.tif
140       Create overviews, embedded in the supplied TIFF file:
141       gdaladdo -r average abc.tif 2 4 8 16
142       Create an external compressed GeoTIFF overview file from the ERDAS .IMG
143       file:
144       gdaladdo -ro --config COMPRESS_OVERVIEW DEFLATE erdas.img 2 4 8 16
145       Create an external JPEG-compressed GeoTIFF overview file from a 3-band
146       RGB dataset (if the dataset is a writable GeoTIFF, you also need to add
147       the -ro option to force the generation of external overview):
148       gdaladdo --config COMPRESS_OVERVIEW JPEG --config PHOTOMETRIC_OVERVIEW YCBCR
149                --config INTERLEAVE_OVERVIEW PIXEL rgb_dataset.ext 2 4 8 16
150       Create an Erdas Imagine format overviews for the indicated JPEG file:
151       gdaladdo --config USE_RRD YES airphoto.jpg 3 9 27 81

AUTHORS

153       Frank Warmerdam warmerdam@pobox.com, Silke Reimer silke@intevation.de
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157GDAL                            Wed Oct 3 2018                     gdaladdo(1)
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