pkcomposite1

Usage

Overview

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)

FC
pkcomposite -i input1.tif -i input2.tif -o output.tif -cr maxndvi -cb 0 -cb 1
      F[0]

Example: Calculate the minimum nadir composite of two input images, where the forth band (b=3) contains the view zenith angle

FC
pkcomposite -i input1.tif -i input2.tif -o minzenith.tif -cr minband -cb 3
      F[0]

Example: Calculate the minimum of two input images in all bands

FC
pkcomposite -i input1.tif -i input2.tif -o minimum.tif -cr minallbands
      F[0]

Options

FC-iF[0] filename, FC--inputF[0] filename

Input image file(s). If input contains multiple images, a multi-band output is created

FC-oF[0] filename, FC--outputF[0] filename

Output image file

FC-bF[0] band, FC--bandF[0] band

band index(es) to crop (leave empty if all bands must be retained)

FC-dxF[0] xres, FC--dxF[0] xres

Output resolution in x (in meter) (empty: keep original resolution)

FC-dyF[0] yres, FC--dyF[0] yres

Output resolution in y (in meter) (empty: keep original resolution)

FC-eF[0] vector, FC--extentF[0] vector

get boundary from extent from polygons in vector file

FC-cutF[0], FC--crop_to_cutlineF[0]

Crop the extent of the target dataset to the extent of the cutline

FC-eoF[0] options, FC--eoF[0] options

Special extent options controlling rasterization: FCATTRIBUTE|CHUNKYSIZE|ALL_TOUCHED|BURN_VALUE_FROM|MERGE_ALGF[0], e.g., FC-eoF[0] FCATTRIBUTE=F[0]fieldname

FC-mF[0] mask, FC--maskF[0] mask

Use the first band of the specified file as a validity mask (0 is nodata)

FC-msknodataF[0] value, FC--msknodataF[0] value

Mask value not to consider for composite

FC-mskbandF[0] value, FC--mskbandF[0] value

Mask band to read (0 indexed)

FC-ulxF[0] ULX, FC--ulxF[0] ULX

Upper left x value bounding box

FC-ulyF[0] ULY, FC--ulyF[0] ULY

Upper left y value bounding box

FC-lrxF[0] LRX, FC--lrxF[0] LRX

Lower right x value bounding box

FC-lryF[0] LRY, FC--lryF[0] LRY

Lower right y value bounding box

FC-crF[0] rule, FC--cruleF[0] rule

Composite rule (overwrite, maxndvi, maxband, minband, mean, mode (only for byte images), median, sum

FC-cbF[0] band, FC--cbF[0] band

band index used for the composite rule (e.g., for ndvi, use FC--cband=0F[0] FC--cband=1F[0] with 0 and 1 indices for red and nir band respectively

FC-srcnodataF[0] value, FC--srcnodataF[0] value

invalid value for input image

FC-bndnodataF[0] band, FC--bndnodataF[0] band

Bands in input image to check if pixel is valid (used for srcnodata, min and max options)

FC-minF[0] value, FC--minF[0] value

flag values smaller or equal to this value as invalid.

FC-maxF[0] value, FC--maxF[0] value

flag values larger or equal to this value as invalid.

FC-dstnodataF[0] value, FC--dstnodataF[0] value

nodata value to put in output image if not valid or out of bounds.

FC-rF[0] resampling_method, FC--resampling-methodF[0] resampling_method

Resampling method (near: nearest neighbor, bilinear: bi-linear interpolation).

FC-otF[0] type, FC--otypeF[0] type

Data type for output image ({Byte / Int16 / UInt16 / UInt32 / Int32 / Float32 / Float64 / CInt16 / CInt32 / CFloat32 / CFloat64}). Empty string: inherit type from input image

FC-ofF[0] GDALformat, FC--oformatF[0] GDALformat

Output image format (see also gdal_translate(1)). Empty string: inherit from input image

FC-coF[0] NAME=VALUE, FC--coF[0] NAME=VALUE

Creation option for output file. Multiple options can be specified.

FC-a_srsF[0] EPSG:number, FC--a_srsF[0] 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)

FC-vF[0], FC--verboseF[0]

verbose

Advanced options

FC-fileF[0], FC--fileF[0]

write number of observations (1) or sequence nr of selected file (2) for each pixels as additional layer in composite. Default: 0

FC-wF[0] weight, FC--weightF[0] 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.

FC-cF[0] name, FC--classF[0] 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.

FC-ctF[0] filename, FC--ctF[0] filename

colour table in ASCII format having 5 columns: id R G B ALFA (0: transparent, 255: solid)

FC-alignF[0], FC--alignF[0]

Align output bounding box to first input image

FC-scaleF[0] value, FC--scaleF[0] value

Scale value FCoutput=scale*input+offsetF[0]

FC-offF[0] value, FC--offsetF[0] value

Offset value FCoutput=scale*input+offsetF[0]

FC-dF[0] description, FC--descriptionF[0] description

Set image description

Examples

Create a composit from two input images. If images overlap, keep only last image (default rule)

FC
pkcomposite -i input1.tif -i input2.tif -o output.tif
      F[0]

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

FC
pkcomposite -i input1.tif -i input2.tif -srcnodata 255 -bndnodata 1 -dstnodata 0 -o output.tif
      F[0]

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).

FC
pkcomposite -i input1.tif -i input2.tif -cr maxndvi -rb 0 -rb 1 -srcnodata 255 -bndnodata 0 -dstnodata 0 -o output.tif
      F[0]

Create a composite image using weighted mean: output=(3/4*input1+6/4*input2+3/4*input2)/3.0

FC
pkcomposite -i input1.tif -i input2.tif -i input3.tif -o output.tif -cr mean -w 0.75 -w 1.5 -w 0.75
      F[0]

Create a median composit of all GTiff images found in current directory that cover (at least part of) the image FCcoverage.tifF[0]. Values smaller or equal to 0 are set as nodata 0 (default value for FC-dstnodataF[0])

FC
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
      F[0]

Faq

Q1. First question

A1. For individual invalid value(s) in input image, use FC-srcnodataF[0]

Usage: use unique value for each invalid bands set in FC--bndnodataF[0] or use a single value that will be applied to all invalid bands

Example:

FC
pkcomposite -i input1.tif -i input2.tif -o output.tif -srcnodata 0 -srcnodata 255 -bndnodata 0 -bndnodata 1
      F[0]

will consider 0 in band 0 and 255 in band 1 of input images as no value

FC
pkcomposite -i input1.tif -i input2.tif -o output.tif -srcnodata 0 -bndnodata 0 -bndnodata 1
      F[0]

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 FC-minF[0] (FC--minF[0]) and FC-maxF[0] (FC--maxF[0]) Usage: use unique range set for each invalid bands set in FC-bndnodataF[0]

Example:

FC
pkcomposite -i input1.tif -i input2.tif -o output.tif -min 0 -max 200 -min 0 -max 2 -bndnodata 0 -bndnodata 1
      F[0]

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