Inconsistent DB values converted by two methods

s1tbx
#1

Hi，I have a question，i’ve already done some preprocessing（apply orbit>TNR>CAL>multilooking>filtering>TC>slope normalisation>to db）,but when I want to linear the band （via right click）generated by the slope normalisation process，i found that the “linear to db” button cannot be selected.So I use the bandmath tool to generate db images.However, the calculated results（Histograms ，data distribution，max and min） are inconsistent.I want to know which method is wrong and where is the problem.
First method:
10log10((Sigma0_VVsin(PIprojectedLocalIncidenceAngle/180))/sin(PIincidenceAngleFromEllipsoid/180))
Second method:(Sigma0_VV_dbsin(PIprojectedLocalIncidenceAngle/180))/sin(PI*incidenceAngleFromEllipsoid/180)
The first method is that calculate directly from Bandmath；
The second method is linear the band generating by TC to db，and then use slope normalisation.

Zhang

#2

Sorry, who can help me? Or because of lack of data？

#3

how do you perform the “slope normalization”?

#4

XP}V}XY0R1LEY_B{_RCPJ4W.png720×621 37.6 KB
via “graphbuilder”

#5

so you used the same formula, once in the graph tool and once in the band maths and they produced different results?

#6

another method is “Sigma0_VV_dbsin(PIprojectedLocalIncidenceAngle/180))/sin(PI*incidenceAngleFromEllipsoid/180)”
Sigma0_VV_db is generated by “linear the band” （right click sigma_VV after Terrain Correction )

#7

why would you want a db band make linear when you just converted it to db?

#8

i am sorry，I want to reopen a topic and post the data.