[GRASS-user] Regarding Atmospheric Correction Model Output

Daniel Victoria daniel.victoria at gmail.com
Tue Nov 17 10:37:18 PST 2015


Dir you try to do a color balance on the corrected images? It's been a
while since I've done this but I believe i.colors.enhance should do it.
https://grass.osgeo.org/grass70/manuals/i.colors.enhance.html

On Sun, Nov 15, 2015 at 12:57 AM, iat bd <imtiazataher at gmail.com> wrote:

> Date: November 15, 2015
>
>
> Hi All,
>
>
> Following are my procedure, observation and question/ request:
>
>
> Data Source: Earth Explorer Landsat 8
>
> Grass GIS Version: 7.0.2 RC1
>
> Windows 7 32 bit OS
>
>
> I have been trying to conduct an Atmospheric correction using the Grass
> wiki reference
>
> https://grasswiki.osgeo.org/wiki/Atmospheric_correction
>
> https://grass.osgeo.org/grass64/manuals/i.atcorr.html
>
> https://grass.osgeo.org/grass64/manuals/i.landsat.toar.html
>
>
> Step 01:
>
>
> I skipped using the Toar Tool and used Raster map calculator to generate
>
> a). Reflectance = REFLECTANCE_MULT_BAND_X*DN + REFLECTANCE_ADD_BAND_X
>
> b). Reflectance with correction of sun angle = Reflectance/ Sin(Ɵ)
>
>
> Step 02:
>
>
> Plugged in to i.atcorr the Reflectance bands generated at Step 01 for band
> 4, 3, 2 amd 8 along with their respective control file.
>
>
> Step 03: IHS Pan Sharpened band 4,3,2 with band 8
>
>
> Step 04: Generated a RGB composite using Red = band 4, Green = band 3 and
> Blue = band 2.
>
>
> I am attaching the resultant image and original unadjusted 432 composites
> for comparison. Obviously, I missed something. Atmospherically adjusted
> Image should’ve been clearer. Its not even looking like an RGB image.
>
>
> Also attaching the Command outputs so that you may follow my steps, to
> notice if there was anything unusual and a control file for reference. I
> used Tropical Atmospheric model and Urban Aerosol model. The values used in
> the control file were collected from Atmospheric correction wiki.
>
>
> I’ll appreciate it if anyone of you can share your insight and tell me how
> I can get a correct atmospherically adjusted image. Also, I noticed there
> is no longer any i.landsat.dehaze extension available. Could you please
> tell me how dehazing may be possible absent the extension?
>
>
> Do let me know if there is anything missing or not clearly explained.
>
>
>
> Thanks in advance.
>
>
>
> Regards,
>
>
>
> Imtiaz
>
>
>
>
>
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>
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