[GRASS-user] Pan sharpen Worldview-2 imagery

[Nikos Alexandris]

William Hudspeth:

>Hello,

Hello William,

>I was wondering whether anyone has a workflow to pan sharpen Worldview-2
>imagery (0.5 m pan, and 2.0 m MS) with 5 bands (panchromatic, red, blue,
>green, NIR).

>I am using grass 7.0.3 on ubuntu 16.01, but cannot find the
>i.fusion.hbf command. I would also like information on any
>pre-processing I might need to perform, such as converting digital
>number to reflectance.

A simple workflow, would be to *first*, ortho-rectify your images
based on their own RPCs. You might want to read this à propos:
http://fwarmerdam.blogspot.ch/2013/09/exploring-rpcs.html

Next, you can create a Location based on the image's own reference
system, like:

grass70 -c WorldView2_Image.TIF /projects/grassdb/location_name

of course, you would (re-)name the above as it fits for you.

Now, inside GRASS,

1. import bands (pan and multispectral) in grass' data base using `r.in.gdal` -- bands will
likely get a basename (the one given for `output=`, and a number as a
suffix if the number of bands is more than 3, I think).

2. optionally, rename for the imported multispectral bands their names to easier
know which is which (like instead of ".1" , "blue" or whatsoever fits).

3. you may want to use
https://github.com/NikosAlexandris/i.worldview.toar to convert digital
numbers to radiance or reflectance. An example command:

i.worldview.toar
band=11APR03001446-M2AS_R1C1.Blue,11APR03001446-M2AS_R1C1.Green,11APR03001446-M2AS_R1C1.Red,11APR03001446-M2AS_R1C1.NIR
outputsuffix=Rad utc=2011-04-03T00:14:46.590888Z sea=44.1

4. Then you can use i.fusion.hpf to sharpen all multispectral bands in
one go like:

i.fusion.hpf pan=Panchromatic msx=msRed,msBlue,msGreen,msNIR

given, of course, the appropriate band names.

>Any assistance is much appreciated...
>Thanks

You might want to have a look at
https://grasswiki.osgeo.org/wiki/WorldView and assist in cleaning it up
and improving it.

Nikos