populateStats error in nodata values

[Carlos Leandro Cordeiro]

Hi everyone, 

I'm trying to apply the populatestats in my segmented image, however it's considering the -9999 and -32768 values as real values and not NoData. 

I tried change to Nodata using "gdalwarp -dstnodata -9999 input.tif output.tif" but it didn't work. 

Other values like 3.4028e38 or -1.7e308 is ok in statistic calculation.

Is there any command I can put in the script to consider these values as nodata?

Thanks

[Daniel Clewley]

Hi Carlos,

Currently the populateStats command only accepts 0 as a no data value so you will need to change the no-data values from -9999 to 0, you can do this using the imagemath command in RSGISLib.

Thanks,

Dan

--
You received this message because you are subscribed to the Google Groups "RSGISLib Support" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rsgislib-suppo...@googlegroups.com.
To post to this group, send email to rsgislib...@googlegroups.com.
Visit this group at https://groups.google.com/group/rsgislib-support.
For more options, visit https://groups.google.com/d/optout.

[Carlos Leandro Cordeiro]

Thanks Dan,

I found a problem in the expression. 

I searched how would be to change -9999 to 0, but I think I made a mistake. 

Sorry, but I'm new to python and this expression is a challenge to me.

import rsgislib

from rsgislib import imagecalc

outputImage = 'slope.tif'

gdalformat = 'GTiff'

datatype = rsgislib.TYPE_32FLOAT

expression = 'b1==-9999:0'

imagecalc.imageMath("slope_MA.tif", outputImage, expression, gdalformat, datatype)

Thanks

[Nathan Thomas]

Try, b1==-9999?0:b1. This is an if (?) else (:) statement that says, if b1 is -9999 then give it a value of 0, else keep the value the same.

Nathan

[Nathan Thomas]

[Carlos Leandro Cordeiro]

Hi Nathan and Dan,

It worked well.

Thanks