Convert Window to Pixel Image
Convert a window to a pixel image by measuring the area of intersection between the window and each pixel in a raster.
## S3 method for class 'owin' pixellate(x, W = NULL, ..., DivideByPixelArea=FALSE)
x |
Window (object of class |
W |
Optional. Window determining the pixel raster on which the conversion should occur. |
... |
Optional. Extra arguments passed to |
DivideByPixelArea |
Logical value, indicating whether the resulting pixel values should be divided by the pixel area. |
This is a method for the generic function pixellate.
It converts a window x into
a pixel image, by measuring the amount of x that is
inside each pixel.
(The related function as.im
also converts x into a pixel image,
but records only the presence or absence of
x in each pixel.)
The pixel raster for the conversion is determined by the
argument W and the extra arguments ....
If W is given, and it is a binary mask (a window
of type "mask") then it determines the pixel raster.
If W is given, but it is not a binary mask (it is a
window of another type) then it will be converted to a binary mask
using as.mask(W, ...).
If W is not given, it defaults to
as.mask(as.rectangle(x), ...)
In the second and third cases it would be common to use the
argument dimyx to control the number of pixels. See the Examples.
The algorithm then computes the area of intersection of each pixel with the window.
The result is a pixel image with pixel entries equal to these intersection areas.
A pixel image (object of class "im").
Adrian Baddeley Adrian.Baddeley@curtin.edu.au and Rolf Turner r.turner@auckland.ac.nz
plot(pixellate(letterR, dimyx=15)) W <- grow.rectangle(as.rectangle(letterR), 0.2) plot(pixellate(letterR, W, dimyx=15))
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