pkcomposite

NAME

pkcomposite - program to mosaic and composite geo-referenced images

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 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