ursa_crop: Crop 'no data' margins.
In ursa: Non-Interactive Spatial Tools for Raster Processing and Visualization

Description Usage Arguments Details Value Author(s) Examples

Function ursa_crop makes such spatial subset of source raster image, where margins of 'no data' values are absent or have specified width.

1	ursa_crop(obj, condition, border = 0, resetGrid = TRUE, verbose = FALSE)

`obj`	Object of class `ursaRaster`
`condition`	Object of class `ursaRaster` or `missing`. The condition for cutting. If ‘missing’ then condition is defined from `obj`.
`border`	Integer of length 1 or 4. Desired margins for geographical subset. Units are cells (pixels).
`resetGrid`	Logical. If `resetGrid=TRUE` then sessional grid paramaters is established from grid parameters of created raster. If `resetGrid=FALSE` then sessional grid parameters keep without change. Defailu is `TRUE`.
`verbose`	Logical. `TRUE` provides some additional information on console.

This function calls regrid with passing values of arguments resetGrid and verbose without changes.

This function is an instrument for data compression for spatial matrices with wide margins of 'no data' value. It keeps spatial structure (pixel's neighborhood) in the internal data storage. Otherwise, compress reduces object size using spatial indexing with dropping of spatial structure.

Object of class ursaRaster

Nikita Platonov platonov@sevin.ru

session_grid(NULL)
'printCR' <- function(obj) print(with(ursa_grid(obj),c(c=columns,r=rows)))
g0 <- session_grid()
a <- pixelsize()
th <- with(ursa_grid(a),resx*resy*1e-6)
a0 <- a[a>th*0.9]
print(session_grid())
printCR(a0)
print(a0)
a1 <- ursa_crop(a0,resetGrid=TRUE)
print(session_grid())
printCR(a1)
print(a1)
a2 <- ursa_crop(a0,resetGrid=FALSE)
print(session_grid())
printCR(a2)
print(a2)
a3 <- a[a>=th*0.85 & a<=th*1.01]
b1 <- ursa_dummy(nband=3,min=0,max=255)
print(b1)
b2 <- ursa_crop(b1[a3>0],border=10)
print(b2)
printCR(b2)
b2[is.na(b2)] <- 255
display_rgb(b2)
b3 <- ursa_crop(b1,a3,border=0)
print(b3)
printCR(b3)