[R-sig-Geo] How to upscale (reduce the spatial resolution) an image using a Gaussian filter in R?

[Nikolaos Tziokas]

Hi,

I want to resample a raster from 15m to 460m (pixel size) using a Gaussian
filter.

*The goal*

I am having a coarse image which I want to downscale. I also have a fine
resolution band to assist the downscaling. The downscaling method I am
using is called geographically weighted area-to-point regression Kriging
(GWATPRK). The method consists of two steps:

   1. GWR
   2. area-to-point Kriging on the GWR's residuals

In order to perform GWR using raster data, those needs to have the same
pixel size. This means that, my fine resolution image needs to be upscaled
to match the spatial resolution of the coarse band. This upscaling of the
fine band needs to be done using a Gaussian kernel with σ=0.5(i.e., the
PSF).

How can I upscale (reduce the spatial resolution) a satellite image using a
Gaussian kernel (i.e., point spread function)?

For reference, I am following the paper The effect of point spread function
on downscaling continua
<https://www.sciencedirect.com/science/article/pii/S092427162030229X> where
the authors at p.253 in Eq (9) mention:

*the coarse image produced by upscaling the corresponding fine band k using
a PSF.*

I googled how I can achieve that but unfortunately I couldn't find any
solution. So to do this, how can I use this Gaussian filter to change the
resolution (pixel size) of my image?

Here is the image
<https://drive.google.com/drive/folders/18_1Kshb8WbT04gwOw4d_xhfQenULDXdB?usp=sharing>
I
am trying to convolve.


Many thanks


-- 
Tziokas Nikolaos
Cartographer

Tel:(+44)07561120302
LinkedIn <http://linkedin.com/in/nikolaos-tziokas-896081130>

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