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GDALBUILDVRT(1) |
GDAL |
GDALBUILDVRT(1) |
gdalbuildvrt - Builds a VRT from a list of datasets.
gdalbuildvrt [--help] [--long-usage] [--help-general]
[--quiet]
[[-strict]|[-non_strict]]
[-tile_index <field_name>]
[-resolution user|common|average|highest|lowest|same]
[-tr <xres> <yes>] [-input_file_list <filename>] [-separate]
[-allow_projection_difference] [-sd <n>] [-tap]
[-te <xmin> <ymin> <xmax> <ymax>] [-addalpha] [-b <band>]...
[-hidenodata] [-overwrite]
[-srcnodata "<value>[ <value>]..."]
[-vrtnodata "<value>[ <value>]..."] [-a_srs <srs_def>]
[-r nearest|bilinear|cubic|cubicspline|lanczos|average|mode]
[-oo <NAME>=<VALUE>]... [-co <NAME>=<VALUE>]...
[-ignore_srcmaskband]
[-nodata_max_mask_threshold <threshold>]
<vrt_dataset_name> [<src_dataset_name>]...
This program builds a VRT (Virtual Dataset) that is a
mosaic of a list of input GDAL datasets. The list of input GDAL datasets can
be specified at the end of the command line, put in a text file (one
filename per line) for very long lists, or it can be a MapServer tileindex
(see the gdaltindex utility). If using a tile index, all entries in
the tile index will be added to the VRT.
NOTE:
Starting with GDAL 3.9, for virtual mosaics with a very
large number of source rasters (hundreds of thousands of source rasters, or
more), it is advised to use the gdaltindex utility to generate a tile
index compatible with the GTI driver.
With -separate, each input goes into a separate band in the
VRT dataset. Otherwise, the files are considered as source rasters of a
larger mosaic and the VRT file has the same number of bands as the input
files.
If one GDAL dataset is made of several subdatasets and has 0
raster bands, all the subdatasets will be added to the VRT rather than the
dataset itself.
gdalbuildvrt does some checks to ensure that all files that
will be put in the resulting VRT have similar characteristics: number of
bands, projection, color interpretation, etc. If not, files that do not
match the common characteristics will be skipped unless -strict is
used. (This is only true in the default mode, and not when using the
-separate option)
If the inputs spatially overlap, the order of the input list is
used to determine priority. Files that are listed at the end are the ones
from which the content will be fetched. Note that nodata will be taken into
account to potentially fetch data from lower-priority datasets, but
currently, alpha channel is not taken into account to do alpha compositing
(so a source with alpha=0 appearing on top of another source will override
its content). This might be changed in later versions.
- --help
- Show this help message and exit
- --help-general
- Gives a brief usage message for the generic GDAL commandline options and
exit.
- -tileindex
<field_name>
- Use the specified value as the tile index field, instead of the default
value which is 'location'.
- -resolution
{highest|lowest|average|user|same}
- In case the resolution of all input files is not the same, the
-resolution flag enables the user to control the way the output
resolution is computed.
highest will pick the smallest values of pixel
dimensions within the set of source rasters.
lowest will pick the largest values of pixel dimensions
within the set of source rasters.
average is the default and will compute an average of
pixel dimensions within the set of source rasters.
user must be used in combination with the -tr
option to specify the target resolution.
same (added in GDAL 3.11) checks that all source
rasters have the same resolution and errors out when this is not the
case.
common (added in GDAL 3.11) determines the greatest
common divisor of the source pixel dimensions, e.g. 0.2 for source pixel
dimensions of 0.4 and 0.6.
- -tr <xres>
<yres>
- Set target resolution. The values must be expressed in georeferenced
units. Both must be positive values. Specifying these values is of course
incompatible with highest|lowest|average values for -resolution
option.
- -tap
- (target aligned pixels) align the coordinates of the extent of the output
file to the values of the -tr, such that the aligned extent
includes the minimum extent. Alignment means that xmin / resx, ymin /
resy, xmax / resx and ymax / resy are integer values.
- -te <xmin> <ymin>
<xmax> <ymax>
- Set georeferenced extents of VRT file. The values must be expressed in
georeferenced units. If not specified, the extent of the VRT is the
minimum bounding box of the set of source rasters. Pixels within the
extent of the VRT but not covered by a source raster will be read as valid
pixels with a value of zero unless a NODATA value is specified using
-vrtnodata or an alpha mask band is added with
-addalpha.
- -addalpha
- Adds an alpha mask band to the VRT when the source raster have none.
Mainly useful for RGB sources (or grey-level sources). The alpha band is
filled on-the-fly with the value 0 in areas without any source raster, and
with value 255 in areas with source raster. The effect is that a RGBA
viewer will render the areas without source rasters as transparent and
areas with source rasters as opaque. This option is not compatible with
-separate.
- -hidenodata
- Even if any band contains nodata value, giving this option makes the VRT
band not report the NoData. Useful when you want to control the background
color of the dataset. By using along with the -addalpha option, you can
prepare a dataset which doesn't report nodata value but is transparent in
areas with no data.
- -srcnodata
"<value>[ <value>]..."
- Set nodata values for input bands (different values can be supplied for
each band). If more than one value is supplied all values should be quoted
to keep them together as a single operating system argument. If the option
is not specified, the intrinsic nodata settings on the source datasets
will be used (if they exist). The value set by this option is written in
the NODATA element of each ComplexSource element. Use a value of
None to ignore intrinsic nodata settings on the source
datasets.
- -ignore_srcmaskband
- Added in version 3.3.
Starting with GDAL 3.3, if a source has a mask band
(internal/external mask band, or alpha band), a
<ComplexSource> element is created by default with a
<UseMaskBand>true</UseMaskBand> child element, to
instruct the VRT driver to use the mask band of the source to mask
pixels being composited. This is a generalization of the NODATA element.
When specifying the -ignore_srcmaskband option, the mask band of
sources will not be taken into account, and in case of overlapping
between sources, the last one will override previous ones in areas of
overlap.
- -nodata_max_mask_threshold
<threshold>
- Added in version 3.9.
Insert a <NoDataFromMaskSource> source, which
replaces the value of the source with the value of -vrtnodata (or
0 if not specified) when the value of the mask band of the source is
less or equal to the threshold. This is typically used to transform a
R,G,B,A image into a R,G,B one with a NoData value.
- -b <band>
- Select an input <band> to be processed. Bands are numbered from 1.
If input bands not set all bands will be added to the VRT. Multiple
-b switches may be used to select a set of input bands.
- -sd <n>
- If the input dataset contains several subdatasets, use a subdataset with
the specified number (starting from 1). This is an alternative to giving
the full subdataset name as an input to the utility.
- -vrtnodata
"<value>[ <value>]..."
- Set nodata values at the VRT band level (different values can be supplied
for each band). If more than one value is supplied, all values should be
quoted to keep them together as a single operating system argument
(Example 4). If the option is not specified, intrinsic nodata
settings on the first dataset will be used (if they exist). The value set
by this option is written in the NoDataValue element of each
VRTRasterBand element. Use a value of None to ignore
intrinsic nodata settings on the source datasets.
- -separate
- Place each input file into a separate band. See Example 3. Contrary
to the default mode, it is not required that all bands have the same
datatype.
Starting with GDAL 3.8, all bands of each input file are added
as separate VRT bands, unless -b is specified to select a subset
of them. Before GDAL 3.8, only the first band of each input file was
placed into a new VRT band, and -b was ignored.
- -allow_projection_difference
- When this option is specified, the utility will create a VRT even if the
input datasets do not have the same projection. Note: this does not mean
that they will be reprojected. Their projection will just be ignored.
- -a_srs
<srs_def>
- Override the projection for the output file. The <srs_def> may be
any of the usual GDAL/OGR forms, complete WKT, PROJ.4, EPSG:n or a file
containing the WKT. No reprojection is done.
- -q
- Disable the progress bar on the console
- -overwrite
- Overwrite the VRT if it already exists.
- -strict
- Turn warnings as failures. This is mutually exclusive with
-non_strict, the latter which is the default.
Added in version 3.4.2.
- -non_strict
- Skip source datasets that have issues with warnings, and continue
processing. This is the default.
Added in version 3.4.2.
gdalbuildvrt doq_index.vrt doq/*.tif
gdalbuildvrt -input_file_list my_list.txt doq_index.vrt
gdalbuildvrt -separate rgb.vrt red.tif green.tif blue.tif
gdalbuildvrt -hidenodata -vrtnodata "0 0 255" doq_index.vrt doq/*.tif
This utility is also callable from C with
GDALBuildVRT().
Even Rouault <even.rouault@spatialys.com>
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