This is an accessor function to quickly access information stored in ImageMetaData, e.g. scale factor per band. Intended for use with imagery which was imported using stackMeta. Will return parameters using the actual band order in img.
Arguments
- img
SpatRaster or character vector with band names.
- metaData
ImageMetaData or path to meta data file.
- what
Character. Parameter to extract. Either data descriptors, or conversion parameters (see Details for options)
Value
If what is one of c('CALRAD', 'CALBT', 'CALREF') a data.frame is returned with bands in rows (order corresponding to img band order).
Otherwise a named numeric vector with the corresponding parameter is returned (layernames as names).
Details
Possible metadata parameters (what argument):
Data descriptors
| 'FILES' | |
| 'QUANTITY' | |
| 'CATEGORY' | |
| 'NA_VALUE' | |
| 'SATURATE_VALUE' | |
| 'SCALE_FACTOR' | |
| 'DATA_TYPE' | |
| 'SPATIAL_RESOLUTION' |
Conversion parameters
| 'CALRAD' | Conversion parameters from DN to radiance |
| 'CALBT' | Conversion parameters from radiance to brightness temperature |
| 'CALREF' | Conversion parameters from DN to reflectance (Landsat 8 only) |
Examples
## Import example data
mtlFile <- system.file("external/landsat/LT52240631988227CUB02_MTL.txt", package="RStoolbox")
meta <- readMeta(mtlFile)
lsat_t <- stackMeta(mtlFile)
## Get integer scale factors
getMeta(lsat_t, metaData = meta, what = "SCALE_FACTOR")
#> B1_dn B2_dn B3_dn B4_dn B5_dn B6_dn B7_dn
#> 1 1 1 1 1 1 1
## Conversion factors for brightness temperature
getMeta("B6_dn", metaData = meta, what = "CALBT")
#> K1 K2
#> B6_dn 607.76 1260.56
## Conversion factors to top-of-atmosphere radiance
## Band order not corresponding to metaData order
getMeta(lsat_t[[5:1]], metaData = meta, what = "CALRAD")
#> offset gain
#> B5_dn -0.49035 0.120
#> B4_dn -2.38602 0.876
#> B3_dn -2.21398 1.044
#> B2_dn -4.16220 1.322
#> B1_dn -2.19134 0.671
## Get integer scale factors
getMeta(lsat_t, metaData = meta, what = "SCALE_FACTOR")
#> B1_dn B2_dn B3_dn B4_dn B5_dn B6_dn B7_dn
#> 1 1 1 1 1 1 1
## Get file basenames
getMeta(lsat_t, metaData = meta, what = "FILES")
#> B1_dn B2_dn
#> "LT52240631988227CUB02_B1.TIF" "LT52240631988227CUB02_B2.TIF"
#> B3_dn B4_dn
#> "LT52240631988227CUB02_B3.TIF" "LT52240631988227CUB02_B4.TIF"
#> B5_dn B6_dn
#> "LT52240631988227CUB02_B5.TIF" "LT52240631988227CUB02_B6.TIF"
#> B7_dn
#> "LT52240631988227CUB02_B7.TIF"