I'm working with a multiband raster and I want to extract each band to a single raster band. I tried two approaches using R (raster) and QGIS (gdal translate).
I noticed that the output file from QGIS is around 25MB while the output file from R is around 2MB. The original multiband raster is around 490MB with 19 bands. This led me to thinking that the QGIS output is more reasonable to use. Note that I will use the bands for SDM.
Is the R output still useable for this purpose? Can you also explain the difference in file sizes?
The usual suspect is file compression of the output. Various software can have different defaults and choices.
its happen maybe - When creating new images or exporting existing images the bit-depth may change. This results in a change in the amount of disk space the new image requires. This happens for a number of reasons, discussed in articles in the Related Information, below. The reason is due to the amount of bits required to store each individual pixel (cell) in a raster image. When working with 8 bit images, 1 byte (8 bits) is required to store each pixel in the image. When working with 16 bit images, 2 bytes are required, and with 32 bit images, 4 bytes are required and so on.
An easy way to determine the approximate size of the image is to use the formula below:
Rows x Columns x number of bands x pixel depth (8 bits = 1 byte)
For example:
8-bit image:
100 rows x 100 columns x 3 bands x 1 = an output raster that is approximately 30,000 bytes in size.
32-bit image:
1000 rows x 1000 columns x 1 band x 4 = an output raster that is approximately 4,000,000 bytes. (esrisupport)
plz check the "bit" on your both output file
The main difference between using R and QGIS to extract bands from a multiband raster is the format of the output files. In R, the output files will be in the form of an R object, while in QGIS, the output files will be in the form of a GeoTIFF, PNG, or other raster format. Additionally, QGIS allows for more customization when extracting bands, such as selecting which bands to extract, setting no data values, and setting the resolution of the output file.
