SYNOPSIS
pkcomposite -i input [-i input] -o output [options] [advanced options]DESCRIPTION
pkcomposite can be used to {mosaic} and {composite} multiple (georeferenced) raster datasets. A mosaic can merge images with different geographical extents into a single larger image. Compositing resolves the overlapping pixels according to some rule (e.g, the median of all overlapping pixels). This utility is complementary to GDAL, which currently does not support a composite step. Input datasets can have different bounding boxes and spatial resolutions.Example: Calculate the maximum NDVI composite of two multispectral input images (e.g., red is band 0 and near infrared is band 1)
pkcomposite -i input1.tif -i input2.tif -o output.tif -cr maxndvi -cb 0 -cb 1
Example: Calculate the minimum nadir composite of two input images, where the forth band (b=3) contains the view zenith angle
pkcomposite -i input1.tif -i input2.tif -o minzenith.tif -cr minband -cb 3
Example: Calculate the minimum of two input images in all bands
pkcomposite -i input1.tif -i input2.tif -o minimum.tif -cr minallbands
OPTIONS
- -i filename, --input filename
- Input image file(s). If input contains multiple images, a multi-band output is created
- -o filename, --output filename
- Output image file
- -b band, --band band
- band index(es) to crop (leave empty if all bands must be retained)
- -dx xres, --dx xres
- Output resolution in x (in meter) (empty: keep original resolution)
- -dy yres, --dy yres
- Output resolution in y (in meter) (empty: keep original resolution)
- -e vector, --extent vector
- get boundary from extent from polygons in vector file
- -cut, --crop_to_cutline
- Crop the extent of the target dataset to the extent of the cutline
- -eo options, --eo options
- Special extent options controlling rasterization: ATTRIBUTE|CHUNKYSIZE|ALL_TOUCHED|BURN_VALUE_FROM|MERGE_ALG, e.g., -eo ATTRIBUTE=fieldname
- -m mask, --mask mask
- Use the first band of the specified file as a validity mask (0 is nodata)
- -msknodata value, --msknodata value
- Mask value not to consider for composite
- -mskband value, --mskband value
- Mask band to read (0 indexed)
- -ulx ULX, --ulx ULX
- Upper left x value bounding box
- -uly ULY, --uly ULY
- Upper left y value bounding box
- -lrx LRX, --lrx LRX
- Lower right x value bounding box
- -lry LRY, --lry LRY
- Lower right y value bounding box
- -cr rule, --crule rule
- Composite rule (overwrite, maxndvi, maxband, minband, mean, mode (only for byte images), median, sum
- -cb band, --cb band
- band index used for the composite rule (e.g., for ndvi, use --cband=0 --cband=1 with 0 and 1 indices for red and nir band respectively
- -srcnodata value, --srcnodata value
- invalid value for input image
- -bndnodata band, --bndnodata band
- Bands in input image to check if pixel is valid (used for srcnodata, min and max options)
- -min value, --min value
- flag values smaller or equal to this value as invalid.
- -max value, --max value
- flag values larger or equal to this value as invalid.
- -dstnodata value, --dstnodata value
- nodata value to put in output image if not valid or out of bounds.
- -r resampling_method, --resampling-method resampling_method
- Resampling method (near: nearest neighbor, bilinear: bi-linear interpolation).
- -ot type, --otype type
- Data type for output image ({Byte / Int16 / UInt16 / UInt32 / Int32 / Float32 / Float64 / CInt16 / CInt32 / CFloat32 / CFloat64}). Empty string: inherit type from input image
- -of GDALformat, --oformat GDALformat
- Output image format (see also gdal_translate(1)). Empty string: inherit from input image
- -co NAME=VALUE, --co NAME=VALUE
- Creation option for output file. Multiple options can be specified.
- -a_srs EPSG:number, --a_srs EPSG:number
- Override the spatial reference for the output file (leave blank to copy from input file, use epsg:3035 to use European projection and force to European grid)
- -v, --verbose
- verbose
Advanced options
- -file, --file
- write number of observations (1) or sequence nr of selected file (2) for each pixels as additional layer in composite. Default: 0
- -w weight, --weight weight
- Weights (type: short) for the composite, use one weight for each input file in same order as input files are provided). Use value 1 for equal weights.
- -c name, --class name
- classes for multi-band output image: each band represents the number of observations for one specific class. Use value 0 for no multi-band output image.
- -ct filename, --ct filename
- colour table in ASCII format having 5 columns: id R G B ALFA (0: transparent, 255: solid)
- -align, --align
- Align output bounding box to first input image
- -scale value, --scale value
- Scale value output=scale*input+offset
- -off value, --offset value
- Offset value output=scale*input+offset
- -d description, --description description
- Set image description
EXAMPLE
Create a composit from two input images. If images overlap, keep only last image (default rule)
pkcomposite -i input1.tif -i input2.tif -o output.tif
Create a composit from two input images. Values of 255 in band 1 (starting from 0) are masked as invalid. Typically used when second band of input image is a cloud mask
pkcomposite -i input1.tif -i input2.tif -srcnodata 255 -bndnodata 1 -dstnodata 0 -o output.tif
Create a maximum NDVI (normalized difference vegetation index) composit. Values of 255 in band 0 are masked as invalid and flagged as 0 if no other valid coverage. Typically used for (e.g., MODIS) images where red and near infrared spectral bands are stored in bands 0 and 1 respectively. In this particular case, a value of 255 in the first input band indicates a nodata value (e.g., cloud mask is coded within the data values).
pkcomposite -i input1.tif -i input2.tif -cr maxndvi -rb 0 -rb 1 -srcnodata 255 -bndnodata 0 -dstnodata 0 -o output.tif
Create a composite image using weighted mean: output=(3/4*input1+6/4*input2+3/4*input2)/3.0
pkcomposite -i input1.tif -i input2.tif -i input3.tif -o output.tif -cr mean -w 0.75 -w 1.5 -w 0.75
Create a median composit of all GTiff images found in current directory that cover (at least part of) the image coverage.tif. Values smaller or equal to 0 are set as nodata 0 (default value for -dstnodata)
pkcomposite -i large.tif $(for IMAGE in *.tif;do pkinfo -i $IMAGE --cover $(pkinfo -i coverage.tif -bb);done) -cr median -min 0 -o output.tif
FAQ
Q1. First questionA1. For individual invalid value(s) in input image, use -srcnodata
Usage: use unique value for each invalid bands set in --bndnodata or use a single value that will be applied to all invalid bands
Example:
pkcomposite -i input1.tif -i input2.tif -o output.tif -srcnodata 0 -srcnodata 255 -bndnodata 0 -bndnodata 1
will consider 0 in band 0 and 255 in band 1 of input images as no value
pkcomposite -i input1.tif -i input2.tif -o output.tif -srcnodata 0 -bndnodata 0 -bndnodata 1
will consider 0 in both bands 0 and 1 of input images as no value
For range(s) of invalid values in input images: use -min (--min) and -max (--max) Usage: use unique range set for each invalid bands set in -bndnodata
Example:
pkcomposite -i input1.tif -i input2.tif -o output.tif -min 0 -max 200 -min 0 -max 2 -bndnodata 0 -bndnodata 1
will consider all negative values in band 0 and 1 of input images as invalid. Values larger or equal to 200 in band 0 will be invalid, as well as values larger or equal to 2 in band 1
Q2. If I take the mean value as composit rule for multi-band input images, will the output image contain the mean value of overlapping images in each band?
A2. Yes