Create a mask for images in a raster data cube
Create an image mask based on a band and provided values to filter pixels of images read by raster_cube
| Argument | Description |
|---|---|
| band | name of the mask band |
| min | minimum value, values between min and max will be masked |
| max | maximum value, values between min and max will be masked |
| values | numeric vector; specific values that will be masked. |
| bits | for bitmasks, extract the given bits (integer vector) with a bitwise AND before filtering the mask values, bit indexes are zero-based |
| invert | logical; invert mask |
Values of the selected mask band can be based on a range (by passing min and max) or on a set of values (by passing values). By default pixels with mask values contained in the range or in the values are masked out, i.e. set to NA. Setting invert = TRUE will invert the masking behavior. Passing values will override min and max.
Notice that masks are applied per image while reading images as a raster cube. They can be useful to eliminate e.g. cloudy pixels before applying the temporal aggregation to merge multiple values for the same data cube pixel.
$band
[1] "SCL"
$values
[1] 3 8 9
$invert
[1] FALSE
$bits
NULL
attr(,"class")
[1] "image_mask"$band
[1] "BQA"
$values
[1] 16
$invert
[1] FALSE
$bits
[1] 4
attr(,"class")
[1] "image_mask"$band
[1] "B10"
$min
[1] 8000
$max
[1] 65000
$invert
[1] FALSE
$bits
NULL
attr(,"class")
[1] "image_mask"# image_mask
Create a mask for images in a raster data cube
```{r include=FALSE}
library(gdalcubes)
```
## Description
Create an image mask based on a band and provided values to filter pixels of images
read by [`raster_cube`](raster_cube.Rmd)
## Usage
```r
image_mask(
band,
min = NULL,
max = NULL,
values = NULL,
bits = NULL,
invert = FALSE
)
```
## Arguments
| Argument | Description |
|:------------|:----------------------------------|
| band | name of the mask band |
| min | minimum value, values between `min` and `max` will be masked |
| max | maximum value, values between `min` and `max` will be masked |
| values | numeric vector; specific values that will be masked. |
| bits | for bitmasks, extract the given bits (integer vector) with a bitwise AND before filtering the mask values, bit indexes are zero-based |
| invert | logical; invert mask |
## Details
Values of the selected mask band can be based on a range (by passing `min` and `max`) or on a set of values (by passing `values`). By default
pixels with mask values contained in the range or in the values are masked out, i.e. set to NA. Setting `invert = TRUE` will invert the masking behavior.
Passing `values` will override `min` and `max`.
## Note
Notice that masks are applied per image while reading images as a raster cube. They can be useful to eliminate e.g. cloudy pixels before applying the temporal aggregation to
merge multiple values for the same data cube pixel.
## Examples
```{r}
image_mask("SCL", values = c(3,8,9)) # Sentinel 2 L2A: mask cloud and cloud shadows
image_mask("BQA", bits=4, values=16) # Landsat 8: mask clouds
image_mask("B10", min = 8000, max=65000)
```