[GRASS-user] unexpected i.pansharpen results

[Nikos Alexandris]

Nikos Alexandris wrote:

> >>> I can't get any decent looking colors, with any of the methods.  I
> >>> wonder if my images are not properly "aligned" or the like.


Moritz Lennert wrote:

> Getting back to this just for clarification. What do you call "decent
> looking colors" ?

apply to my sentence "s/decent looking colors/usable images"


> Have you looked at the example images in the man page [1]?
> [1] http://grass.osgeo.org/grass70/manuals/i.pansharpen.html

Sure.


> They show quite different colors depending on the technique used.

This is not the problem that I have. Nor is it the one Haziq described in the 
Q&A at <http://gis.stackexchange.com/q/39174/5256>.


> Are you trying to get them all to look like the top left ("natural
> color") image ?

No.  I simply try to get usable output from 11-bit bands fed in i.pansharpen.  
The only usable output, no matter the method actually, is when rescaling the 
input bands to 8-bit.  Tested with my working data (IKONOS, QuickBird) as well as with some 
publicly available IKONOS data.

I am delivering 18 examples in which none of them appears ok to me.  I guess I don't know 
how to use the module.  Will post images in trac, if possible, else in my wiki user-page.

I don't provide any 8-bit examples. All of my attempts, so far, with 8-bit images work fine -- 
they look from acceptable to really good depending on some re-balancing, be it manually 
playing with color-tables or using i.landsat.rgb

Nevertheless, I 'd like to see only one example using a >8-bit set of bands in which 
i.pansharpen works as expected.  Then I know for sure that, once again I have messed-up a 
normal runnig process :-).  I am a Great specialist doing this... :D



So, here it goes.


# 1) We have publicly available IKONOS images:

<ftp://ftp.glcf.umd.edu/glcf/China_earthquake_May_2008/IKONOS/>.

Get for example the first one:

<ftp://ftp.glcf.umd.edu/glcf/China_earthquake_May_2008/IKONOS/po_58204_0000000.200011
16.China-Sichuan/>



# 2) Import in GRASS' db, convert from DN to Radiance to Reflectance.  Details 
in the Wiki:

<http://grasswiki.osgeo.org/wiki/IKONOS#Deriving_Physical_Quantities>



# 3) Let's have a look at the "input" ranges:

# 11-bit DNs, ranging in...
min=0
max=1400
title= (po_58204_blu_0000000)
min=0
max=1654
title= (po_58204_grn_0000000)
min=0
max=1321
title= (po_58204_nir_0000000)
min=0
max=1319
title= (po_58204_pan_0000000)
min=0
max=1489
title= (po_58204_red_0000000)

# Radiances
min=0
max=269.716258496062
title= (Blue_Radiance)
min=0
max=259.280160521696
title= (Green_Radiance)
min=0
max=164.2581277309
title= (NIR_Radiance)
min=0
max=203
title= (Pan_Radiance)
min=0
max=238.452890740853
title= (Red_Radiance)


# Reflectances  -- note to self: fix r.support below!
min=0
max=0.705829413346531
title=echo Blue band (Top of Atmosphere Reflectance) (Blue_ToAR)
min=0
max=0.706357576839509
title=echo Green band (Top of Atmosphere Reflectance) (Green_ToAR)
min=0
max=0.717436479668371
title=echo NIR band (Top of Atmosphere Reflectance) (NIR_ToAR)
min=0
max=0.745578096984679
title=echo Pan band (Top of Atmosphere Reflectance) (Pan_ToAR)
min=0
max=0.774115699104528
title=echo Red band (Top of Atmosphere Reflectance) (Red_ToAR)



# 4)  i.pansharpen -- all of them, three methods -- from my history

### Brovey

   18  31.Jul.13 [ 15:54:36 ] i.pansharpen sharpen=brovey pan=Pan_Radiance 
ms1=Blue_Radiance ms2=Green_Radiance ms3=Red_Radiance 
output=sharp_brovey_Radiance

   19  31.Jul.13 [ 15:54:46 ] i.pansharpen sharpen=brovey pan=Pan_ToAR 
ms1=Blue_ToAR 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/grass-user/attachments/20130731/983d7234/attachment-0001.html>