I am trying to calculate radar vegetation index with dual polarization data (VV-VH). So at first I am calculated DOP or Degree of polarization (VV/VV+VH), and after that value of DOP is multiply with RVI formula. Before multiplying DOP value, I am using square root of DOP. The formula is
sqrt(dop)((4VH)/(VV+VH)). The RVI range should be 0 to 1.

But my final image highest value is 1.5 and lowest value is -439666.75. And my final image content are only agriculture area.

So my concern is, is it possible the lowest value come in minus and highest value >1? Also am I doing correct calculation of RVI?

Please guide me on this topic.

I am referring the following pdf https://custom-scripts.sentinel-hub.com/custom-scripts/sentinel-1/radar_vegetation_index/

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are you using data in linear or log scale? This makes a difference for the formula. Also in the source to the script it is not specified if linear or log data was used.

I am using data in linear not log scale. How should I use linear data for RVI?

Sigma0 is linear
Sigma0_dB is log scaled

probably the formula works with dB scaled data.

Right-click on the Sigma0 band and select â€śLinear to/from dBâ€ť

Sorry for wrong information, after geometric correction I have done the â€śLinear to/from dbâ€ť conversion and then I used â€śConvert Bandâ€ť. Then I Export it in Geotiff/Bigtiff.

Please calculate the RVI in SNAP before exporting. Chances are high that the data was rescaled during the export process, leading to different input values for the calculation.

Ok. I am trying to do that. In SNAP how to calculate RVI?

you can access the raster values with the Band Maths: https://www.youtube.com/watch?v=D4lSjLfPVwY

I am calculate the RVI in SNAP but how to check RVI range in SNAP?

After calculating RVI with above described formula, I am exporting the RVI with Two Sigma0_db band and DOP. When image was open in arcgis then value range is showing 1.5 to -3651.56.

with the histogram or statistics tool

Donâ€™t export to GeoTiff, simply open the img files inside the .data folder of the BEAM DIMAP product in ArcMap. Conversion of formats potentially rescales the data.

As your consulting, I am calculated the RVI without linear to db conversion. But RVI value range is come between 0 to 4 where its suppose to be 0 to 1.

So my consulting is why RVI value range is exceeds 1.

is your data calibrated to Sigma0?

Please have a look at the histogram of the RVI to see the range of the data.

Yes my data is calibrated to Sigma0. I checked the histogram, max value showing 4

I understand that, but maybe these are outliers caused by double bounce or volume scattering while the majority of the data lies between 0 and 1.

Please show the histograms of both input products (VV and VH) as well as of the RVI.

I tested with my data and also get some values above 1. The linear scaled RVI looks better than the dB scaled one.

this is how I calculated it

``````DOP = Sigma0_VV / (Sigma0_VV + Sigma0_VH)
RVI  = sqrt(DOP) *((4*(Sigma0_VH))/(Sigma0_VV + Sigma0_VH))
``````

This is the value range

The thing is, the link you provided does not allow to check if this index really ranges between 0 and 1.
I would just see it as a relative measure, regardless of the scaling.

Maybe you can get in touch with the author.

Can you tell me what are the pre-processing steps you followed before calculating RVI? Because this time I am calculating RVI in linear scale but this time I am getting Lowest value in minus and when I am open RVI.img file in arcgis its completely white like this

Radiometric calibration to Sigma0 and Terrain Correction.

You have to apply a correct color stretch in ArcGIS, the nodata value outside is not set correctly. Go to the symbology and stretch the colors between 0 and 2 to have better visual contrasts.

Now its work correctly. Thank you for your guidance.