I have a COG with a scale factor (excerpt from GDALInfo)
Band 1 Block=1024x1024 Type=Int32, ColorInterp=Gray
Min=-50313.000 Max=57304.000
Minimum=-50313.000, Maximum=57304.000, Mean=4745.177, StdDev=7550.452
NoData Value=-32767
Offset: 0, Scale:0.1
How do I apply this scale factor in FME? If I clip the input and create a new tif, the scale factor is dropped and the values are 10 times the expected.
In this particular case I can just scale the value back down, but in general, is there a way to retrieve the scale factor and apply it?
Solved
Scale factor on COG
+40- Contributor
Best answer by crystalatsafe
Hi
Thank you for your patience!
The GeoTIFF Reader can now expose scale and offset factor in Format Attributes, please install the latest version of FME 2026.1 at: safe.com/downloads/
+63- Evangelist
Untested, as I don't have a COG at hand, but the documentation mentions
| geotiff_exif_digitalzoomratio | Represents the digital zoom ratio when the image was shot. If the numerator of the recorded value is 0, this indicates that digital zoom was not used. |
Hopefully this attribute is related to the scale GDALInfo mentions.
+30- Safer
Hi
I don't believe FME currently supports scale factors in GeoTIFF.
I have submitted an internal ticket for our development team (internal reference: FMEENGINE-87393) to explore the possibility of implementing this. I will make sure to update you on the progress.
+40- Contributor
Hi
I don't believe FME currently supports scale factors in GeoTIFF.
I have submitted an internal ticket for our development team (internal reference: FMEENGINE-87393) to explore the possibility of implementing this. I will make sure to update you on the progress.
Even an interim solution where the scale factor can be retrieved as metadata would be a useful step forward.
+40- Contributor
+30- Safer
Hi
I'm sorry for the late response!
While our development team continues to look into this, you could try embedding an external tool or Python into Form.
Perhaps a library like this may be able to extract metadata, such as scale factor: https://pypi.org/project/tifftools/
+30- Safer
- Best Answer
Hi
Thank you for your patience!
The GeoTIFF Reader can now expose scale and offset factor in Format Attributes, please install the latest version of FME 2026.1 at: safe.com/downloads/