topic Re: IRasterProps.NoData doesn´t work whit Iraster2.GetPixelValue. Why? in ArcObjects SDK Questions

IRasterProps.NoData doesn´t work whit Iraster2.GetPixelValue. Why?

martinmaretta — Thu, 14 Nov 2013 13:24:12 GMT

Hi i have code loke belov. I set NoData value to my pRaster (IRaster2) as value - 9999. but when i use GetPixelValue(0, x, y) at pixel location whit NoData i have value = 0. do anybody know where is mistake? Or how to set my NoData Value correctly ?

dim pRaster as IRaster2
.
.
pRasPropsIn = CType(pRaster, IRasterProps)
pRasPropsIn.NoDataValue = -9999 'urcovanie hodnoty no data
.
.
dim pValue as Single
pValue = pRaster.GetPixelValue(0, x, y)

here is pValue = 0 not -9999 !!!!!!

Re: IRasterProps.NoData doesn´t work whit Iraster2.GetPixelValue. Why?

DuncanHornby — Thu, 14 Nov 2013 13:51:37 GMT

Having set the NoData value have you tried to save the raster first using ISaveAs to commit the change? The help file says

These modifications only affect the in-memory raster representation and in no way change any of the raster dataset. You can persist the modifications to a new raster datast using ISaveAs::SaveAs or IRasterBandCollection::SaveAs.

Duncan

Re: IRasterProps.NoData doesn´t work whit Iraster2.GetPixelValue. Why?

martinmaretta — Fri, 15 Nov 2013 05:18:56 GMT

Thanks for reply, but i just need to check value at one point (x,y) and save whole raster is not a good idea, i think. What i need is know if the value is NoData or 0.