pkcomposite(1)

✨ pkcomposite(1) — NAME ✨

pkcomposite — program to mosaic and composite geo-referenced images 💖

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🦋 SYNOPSIS 🦋

pkcomposite -i input [-i input] -o output [options] [advanced options]

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🌸 DESCRIPTION 🌸

okay so bestie, pkcomposite is the girl who can {mosaic} and {composite} a whole pile of (georeferenced) raster datasets at once. 💅

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. no cap 🫶

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

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👑 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

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💖 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

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🎀 FAQ 🎀

Q1. First question

A1. 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 ✨

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okay that's literally the whole page bestie, you're so welcome 💜 this was pkcomposite(1), dated 01 January 2025 — go mosaic something iconic, periodt 🦋👑