[GRASS-user] Re: i.atcorr returns all NULL values

GRASS GRASS user
1

I had same problem, i.atcorr not work with landsat 5TM band 1, 2 and sometimes with band 3
I tried i.atcorr in different versions of grass, this is my results:

  1. GRASS-6.4.1-2 under Mac Snow-Leopard 10.6.7: Not work band 1, 2, and sometimes with band 3 (for years 1992, 1993, 1995 and 1997).
  2. GRASS-6.5. revision 46428 compiled in Mac Snow-Leopard 10.6.7: Not work band 1, 2, and sometimes with band 3 (for years 1992, 1993, 1995 and 1997)
  3. GRASS-6.5svn45719(2011) under Microsoft Windows Xp sp3: All the bands work,THIS IS VERY RARE

My images landsat 5 TM are from Tonameca, Oaxaca, México of years 1985 to 1999, and 2010 to 2011 (one image series for year), i am work with AOD and visibility value, and convert manually DN to radiance (a).

(a) Lλ = [(LMAXλ − LMINλ) / (Qcalmax − Qcalmin)] (Qcal − Qcalmin) + LMINλ

Gaspar Reyes Póndigo
Universidad del Mar, Oaxaca, México
Campus Puerto-Ángel
Carretera principal Puerto Ángel Zipolite km 1.5
C.P. 70902

Message: 1

Date: Fri, 27 May 2011 08:53:32 +0530

From: “Chemin, Yann (IWMI)” <Y.Chemin@cgiar.org>

Subject: RE: [GRASS-user] Re: i.atcorr returns all NULL values

To: “Juan Benavides Duque” <jbenavid@siu.edu>,

<grass-user@lists.osgeo.org>

Cc: Markus Metz <markus.metz.giswork@googlemail.com>, Elena Mezzini

<elena.mezzini@gmail.com>

Message-ID:

<001F233294EA894387CFDAADAB87DE25085063E9@iwmix.IWMI.CGIARAD.ORG>

Content-Type: text/plain; charset=“us-ascii”

Hi Juan,

Can you please give the download link for your images,

Could you also check the output of i.landsat.toar for them and tell if

reflectance ranges are valid/logic.

Thank you,

Yann

From: Juan Benavides Duque [mailto:jbenavid@siu.edu]

Sent: Thursday, May 26, 2011 11:38 PM

To: Chemin, Yann (IWMI)

Cc: Markus Metz; Elena Mezzini

Subject: Re: [GRASS-user] Re: i.atcorr returns all NULL values

I tried Yann’s code for the i.atcorr on some Landsat TM5 images

It worked very nice for images taken after 1995 but before that still

returns null values when running i.atcorr for bands 1 and 2

I used TM5 scenes from the same location for 1986, 1989, and 1996 and

the first two (1986 and 1989) had the same problem with the null

values…

sorry I can provide a way to fix it but I hope somebody will

juan c

On Tue, May 24, 2011 at 3:49 AM, Chemin, Yann (IWMI)

<Y.Chemin@cgiar.org> wrote:

Each created visibility map holds only one value r.mapcalc

expression=“visibility=${vis_list[$i]}” --overwrite so why not just use

this visibility value as input in the >parameter file instead of

creating a map where all cells have the same value?

Yes, this is a valid point, the script is designed to (hopefully soon)

encompass raster maps of visibility data (maybe interpolated…), so

this is a placeholder for the next steps.

-----Original Message-----

From: Markus Metz [mailto:markus.metz.giswork@googlemail.com]

Sent: Tuesday, May 24, 2011 12:52 PM

To: Chemin, Yann (IWMI)

Cc: grass-user@lists.osgeo.org; Elena Mezzini; Markus Neteler

Subject: Re: [GRASS-user] Re: i.atcorr returns all NULL values

On Mon, May 23, 2011 at 9:36 PM, Markus Neteler <neteler@osgeo.org>

wrote:

Hi Yann,

On Mon, May 23, 2011 at 5:07 AM, Chemin, Yann (IWMI)

<Y.Chemin@cgiar.org> wrote:

p192 r030 image of July 2003 of Italy (L5TM) successfully corrected

for band 1 and 2.

The following script works well in GRASS GIS Trunk SVN.

(better send as attachment since a series of line breaks got broken)

…

For i.atcorr scripting

#-----------------------------------------------------

vis_list=(10 10 8 9.7 15 8 7 10 10 9.7 12 9.7 7 12 12 12 3 15 12 9.7

6 15) vis_len=${#vis_list[*]} echo $vis_len

… this is not clear to me: why so many values and where do they

originate from? Since we have only 6 channels to work with…

Moreover, how can it be possible that visibility is different for

different channels of the same scene? From the documentation it seems

that visibility is related to aerosol concentration at 550nm which can

not possibility be different for different bands of the same scene.

Each created visibility map holds only one value r.mapcalc

expression=“visibility=${vis_list[$i]}” --overwrite so why not just use

this visibility value as input in the parameter file instead of creating

a map where all cells have the same value?

Markus M

grass-user mailing list

grass-user@lists.osgeo.org

http://lists.osgeo.org/mailman/listinfo/grass-user

-------------- next part --------------

An HTML attachment was scrubbed…

URL: http://lists.osgeo.org/pipermail/grass-user/attachments/20110527/211bcf66/attachment-0001.html

2

I’m sending the code I used to run the i.atcorr module (including the i.landsat.toar transformation)

(I also used the code sent by Yann Chemin (May 23) with the same results)

Of two files attached one has the code and other one the univariate stats output of the band 1 TOAR raster for one of the 1986 scenes

A copy of the original landsat used have been placed temporarily at the following location " assets "

hope somebody can help

thanks

juan

I’m using a desktop running Ubuntu 10.10 with a 64bit Intel(R) Core™ i7 CPU 860 @ 2.80GHz

2011/5/27 Gaspar Reyes Póndigo <gos47@hotmail.com>

I had same problem, i.atcorr not work with landsat 5TM band 1, 2 and sometimes with band 3
I tried i.atcorr in different versions of grass, this is my results:

  1. GRASS-6.4.1-2 under Mac Snow-Leopard 10.6.7: Not work band 1, 2, and sometimes with band 3 (for years 1992, 1993, 1995 and 1997).
  2. GRASS-6.5. revision 46428 compiled in Mac Snow-Leopard 10.6.7: Not work band 1, 2, and sometimes with band 3 (for years 1992, 1993, 1995 and 1997)
  3. GRASS-6.5svn45719(2011) under Microsoft Windows Xp sp3: All the bands work,THIS IS VERY RARE

My images landsat 5 TM are from Tonameca, Oaxaca, México of years 1985 to 1999, and 2010 to 2011 (one image series for year), i am work with AOD and visibility value, and convert manually DN to radiance (a).

(a) Lλ = [(LMAXλ − LMINλ) / (Qcalmax − Qcalmin)] (Qcal − Qcalmin) + LMINλ

Gaspar Reyes Póndigo
Universidad del Mar, Oaxaca, México
Campus Puerto-Ángel
Carretera principal Puerto Ángel Zipolite km 1.5
C.P. 70902

Message: 1

Date: Fri, 27 May 2011 08:53:32 +0530

From: “Chemin, Yann (IWMI)” <Y.Chemin@cgiar.org>

Subject: RE: [GRASS-user] Re: i.atcorr returns all NULL values

To: “Juan Benavides Duque” <jbenavid@siu.edu>,

<grass-user@lists.osgeo.org>

Cc: Markus Metz <markus.metz.giswork@googlemail.com>, Elena Mezzini

<elena.mezzini@gmail.com>

Message-ID:

<001F233294EA894387CFDAADAB87DE25085063E9@iwmix.IWMI.CGIARAD.ORG>

Content-Type: text/plain; charset=“us-ascii”

Hi Juan,

Can you please give the download link for your images,

Could you also check the output of i.landsat.toar for them and tell if

reflectance ranges are valid/logic.

Thank you,

Yann

From: Juan Benavides Duque [mailto:jbenavid@siu.edu]

Sent: Thursday, May 26, 2011 11:38 PM

To: Chemin, Yann (IWMI)

Cc: Markus Metz; Elena Mezzini

Subject: Re: [GRASS-user] Re: i.atcorr returns all NULL values

I tried Yann’s code for the i.atcorr on some Landsat TM5 images

It worked very nice for images taken after 1995 but before that still

returns null values when running i.atcorr for bands 1 and 2

I used TM5 scenes from the same location for 1986, 1989, and 1996 and

the first two (1986 and 1989) had the same problem with the null

values…

sorry I can provide a way to fix it but I hope somebody will

juan c

On Tue, May 24, 2011 at 3:49 AM, Chemin, Yann (IWMI)

<Y.Chemin@cgiar.org> wrote:

Each created visibility map holds only one value r.mapcalc

expression=“visibility=${vis_list[$i]}” --overwrite so why not just use

this visibility value as input in the >parameter file instead of

creating a map where all cells have the same value?

Yes, this is a valid point, the script is designed to (hopefully soon)

encompass raster maps of visibility data (maybe interpolated…), so

this is a placeholder for the next steps.

-----Original Message-----

From: Markus Metz [mailto:markus.metz.giswork@googlemail.com]

Sent: Tuesday, May 24, 2011 12:52 PM

To: Chemin, Yann (IWMI)

Cc: grass-user@lists.osgeo.org; Elena Mezzini; Markus Neteler

Subject: Re: [GRASS-user] Re: i.atcorr returns all NULL values

On Mon, May 23, 2011 at 9:36 PM, Markus Neteler <neteler@osgeo.org>

wrote:

Hi Yann,

On Mon, May 23, 2011 at 5:07 AM, Chemin, Yann (IWMI)

<Y.Chemin@cgiar.org> wrote:

p192 r030 image of July 2003 of Italy (L5TM) successfully corrected

for band 1 and 2.

The following script works well in GRASS GIS Trunk SVN.

(better send as attachment since a series of line breaks got broken)

…

For i.atcorr scripting

#-----------------------------------------------------

vis_list=(10 10 8 9.7 15 8 7 10 10 9.7 12 9.7 7 12 12 12 3 15 12 9.7

6 15) vis_len=${#vis_list[*]} echo $vis_len

… this is not clear to me: why so many values and where do they

originate from? Since we have only 6 channels to work with…

Moreover, how can it be possible that visibility is different for

different channels of the same scene? From the documentation it seems

that visibility is related to aerosol concentration at 550nm which can

not possibility be different for different bands of the same scene.

Each created visibility map holds only one value r.mapcalc

expression=“visibility=${vis_list[$i]}” --overwrite so why not just use

this visibility value as input in the parameter file instead of creating

a map where all cells have the same value?

Markus M

grass-user mailing list

grass-user@lists.osgeo.org

http://lists.osgeo.org/mailman/listinfo/grass-user

-------------- next part --------------

An HTML attachment was scrubbed…

URL: http://lists.osgeo.org/pipermail/grass-user/attachments/20110527/211bcf66/attachment-0001.html

grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

(attachments)

TOAR FOR BAND1 UNIVARIATE STATS.TXT (868 Bytes)
IATCORR CODE.TXT (915 Bytes)

3

I'm also struggling with i.atcorr for Landsat. A friend of my
corrected some TM images using the Flash module in ENVI (based on
modtran) and I tried to correct the same images using 6S in grass
(i.atcorr). We both used the same radiance images that had some
problems with a few negative values in water areas. I set the negative
values to 0.

After correcting the TM images in Grass I created 6000 random point in
order to compare the images (flash vs. 6s). The attached graph shows
the density plot (~histogram) for each band (band 6 is actually TM
band7). For all images, value have been scaled from 0 to 1. Black line
is radiance, red is 6S and blue is flash. What we see is that for
bands 4, 5 and 7 there are no big differences but, for bands 1, 2 and
3, the correction done by flash is more pronounced.

Now, what I don't know:
1) Is this type of analysis (looking at the image histogram) OK?
2) Should atmospheric correction change the histogram?
3) For i.atcorr I get a sort of "linear" relation between radiance &
reflectance. That is, for each radiance there is only one value for
reflectance. But the flash correction gives a point cloud when I
compare radiance & reflectance (more than one reflectance value for
the same radiance). What is the expected behavior?

I'm using Grass 7 svn from about 2 weeks ago. The images are from the
Pantanal wetland in Brazil in the dry period (still lots of water
there). For 6S the settings are: Tropical atmosphere, continental
aerosol mode, 20km visibility.

Thanks and cheers
Daniel

On Fri, May 27, 2011 at 7:34 PM, Juan Benavides Duque <jbenavid@siu.edu> wrote:

I'm sending the code I used to run the i.atcorr module (including the
i.landsat.toar transformation)

(I also used the code sent by Yann Chemin (May 23) with the same results)

Of two files attached one has the code and other one the univariate stats
output of the band 1 TOAR raster for one of the 1986 scenes

A copy of the original landsat used have been placed temporarily at the
following location " assets "

hope somebody can help

thanks

juan

I'm using a desktop running Ubuntu 10.10 with a 64bit Intel(R) Core(TM) i7
CPU 860 @ 2.80GHz

2011/5/27 Gaspar Reyes Póndigo <gos47@hotmail.com>

I had same problem, i.atcorr not work with landsat 5TM band 1, 2 and
sometimes with band 3
I tried i.atcorr in different versions of grass, this is my results:

1. GRASS-6.4.1-2 under Mac Snow-Leopard 10.6.7: Not work band 1, 2, and
sometimes with band 3 (for years 1992, 1993, 1995 and 1997).
2. GRASS-6.5. revision 46428 compiled in Mac Snow-Leopard 10.6.7: Not work
band 1, 2, and sometimes with band 3 (for years 1992, 1993, 1995 and 1997)
3. GRASS-6.5svn45719(2011) under Microsoft Windows Xp sp3: All the bands
work,THIS IS VERY RARE

My images landsat 5 TM are from Tonameca, Oaxaca, México of years 1985 to
1999, and 2010 to 2011 (one image series for year), i am work with AOD and
visibility value, and convert manually DN to radiance (a).

(a) Lλ = [(LMAXλ − LMINλ) / (Qcalmax − Qcalmin)] (Qcal − Qcalmin) + LMINλ

Gaspar Reyes Póndigo
Universidad del Mar, Oaxaca, México
Campus Puerto-Ángel
Carretera principal Puerto Ángel Zipolite km 1.5
C.P. 70902

-------------------------------------------------------------------

Message: 1

Date: Fri, 27 May 2011 08:53:32 +0530

From: "Chemin, Yann (IWMI)" <Y.Chemin@cgiar.org>

Subject: RE: [GRASS-user] Re: i.atcorr returns all NULL values

To: "Juan Benavides Duque" <jbenavid@siu.edu>,

<grass-user@lists.osgeo.org>

Cc: Markus Metz <markus.metz.giswork@googlemail.com>, Elena Mezzini

<elena.mezzini@gmail.com>

Message-ID:

<001F233294EA894387CFDAADAB87DE25085063E9@iwmix.IWMI.CGIARAD.ORG>

Content-Type: text/plain; charset="us-ascii"

Hi Juan,

Can you please give the download link for your images,

Could you also check the output of i.landsat.toar for them and tell if

reflectance ranges are valid/logic.

Thank you,

Yann

From: Juan Benavides Duque [mailto:jbenavid@siu.edu]

Sent: Thursday, May 26, 2011 11:38 PM

To: Chemin, Yann (IWMI)

Cc: Markus Metz; Elena Mezzini

Subject: Re: [GRASS-user] Re: i.atcorr returns all NULL values

I tried Yann's code for the i.atcorr on some Landsat TM5 images

It worked very nice for images taken after 1995 but before that still

returns null values when running i.atcorr for bands 1 and 2

I used TM5 scenes from the same location for 1986, 1989, and 1996 and

the first two (1986 and 1989) had the same problem with the null

values...

sorry I can provide a way to fix it but I hope somebody will

juan c

On Tue, May 24, 2011 at 3:49 AM, Chemin, Yann (IWMI)

<Y.Chemin@cgiar.org> wrote:

Each created visibility map holds only one value r.mapcalc

expression="visibility=${vis_list[$i]}" --overwrite so why not just use

this visibility value as input in the >parameter file instead of

creating a map where all cells have the same value?

Yes, this is a valid point, the script is designed to (hopefully soon)

encompass raster maps of visibility data (maybe interpolated...), so

this is a placeholder for the next steps.

-----Original Message-----

From: Markus Metz [mailto:markus.metz.giswork@googlemail.com]

Sent: Tuesday, May 24, 2011 12:52 PM

To: Chemin, Yann (IWMI)

Cc: grass-user@lists.osgeo.org; Elena Mezzini; Markus Neteler

Subject: Re: [GRASS-user] Re: i.atcorr returns all NULL values

On Mon, May 23, 2011 at 9:36 PM, Markus Neteler <neteler@osgeo.org>

wrote:

Hi Yann,

On Mon, May 23, 2011 at 5:07 AM, Chemin, Yann (IWMI)

<Y.Chemin@cgiar.org> wrote:

p192 r030 image of July 2003 of Italy (L5TM) successfully corrected

for band 1 and 2.

The following script works well in GRASS GIS Trunk SVN.

(better send as attachment since a series of line breaks got broken)

...

# For i.atcorr scripting

#-----------------------------------------------------

vis_list=(10 10 8 9.7 15 8 7 10 10 9.7 12 9.7 7 12 12 12 3 15 12 9.7

6 15) vis_len=${#vis_list[*]} echo $vis_len

... this is not clear to me: why so many values and where do they

originate from? Since we have only 6 channels to work with...

Moreover, how can it be possible that visibility is different for

different channels of the same scene? From the documentation it seems

that visibility is related to aerosol concentration at 550nm which can

not possibility be different for different bands of the same scene.

Each created visibility map holds only one value r.mapcalc

expression="visibility=${vis_list[$i]}" --overwrite so why not just use

this visibility value as input in the parameter file instead of creating

a map where all cells have the same value?

Markus M

_______________________________________________

grass-user mailing list

grass-user@lists.osgeo.org

http://lists.osgeo.org/mailman/listinfo/grass-user

-------------- next part --------------

An HTML attachment was scrubbed...

URL: http://lists.osgeo.org/pipermail/grass-user/attachments/20110527/211bcf66/attachment-0001.html

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

(attachments)

Screenshot.png

4

Daniel,

this is really interesting, because the different correction methods can
influence the results....

I really would be interested if these strange results of the flaash method
are normal..

-----
Department of Geography and
Regional Research
UZA II, Althanstr. 14
1090 Wien, AUSTRIA
http://geooekologie.univie.ac.at
--
View this message in context: http://osgeo-org.1803224.n2.nabble.com/i-atcorr-returns-all-NULL-values-tp4975543p6422066.html
Sent from the Grass - Users mailing list archive at Nabble.com.

5

Hi Martin,

That's the problem that I'm facing now. Since I'm no expert in
atmospheric correction I don't know which results should I rely on:
Flaash or 6S?

Daniel

On Tue, May 31, 2011 at 6:56 AM, Martin Brandt
<martin.brandt@univie.ac.at> wrote:

Daniel,

this is really interesting, because the different correction methods can
influence the results....

I really would be interested if these strange results of the flaash method
are normal..

-----
Department of Geography and
Regional Research
UZA II, Althanstr. 14
1090 Wien, AUSTRIA
http://geooekologie.univie.ac.at
--
View this message in context: http://osgeo-org.1803224.n2.nabble.com/i-atcorr-returns-all-NULL-values-tp4975543p6422066.html
Sent from the Grass - Users mailing list archive at Nabble.com.
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

6

On Sun, May 29, 2011 at 8:16 PM, Daniel Victoria
<daniel.victoria@gmail.com> wrote:

I'm also struggling with i.atcorr for Landsat. A friend of my
corrected some TM images using the Flash module in ENVI (based on
modtran) and I tried to correct the same images using 6S in grass
(i.atcorr). We both used the same radiance images that had some
problems with a few negative values in water areas. I set the negative
values to 0.

After correcting the TM images in Grass I created 6000 random point in
order to compare the images (flash vs. 6s). The attached graph shows
the density plot (~histogram) for each band (band 6 is actually TM
band7). For all images, value have been scaled from 0 to 1. Black line
is radiance, red is 6S and blue is flash. What we see is that for
bands 4, 5 and 7 there are no big differences but, for bands 1, 2 and
3, the correction done by flash is more pronounced.

Now, what I don't know:
1) Is this type of analysis (looking at the image histogram) OK?
2) Should atmospheric correction change the histogram?
3) For i.atcorr I get a sort of "linear" relation between radiance &
reflectance. That is, for each radiance there is only one value for
reflectance. But the flash correction gives a point cloud when I
compare radiance & reflectance (more than one reflectance value for
the same radiance). What is the expected behavior?

If you use global values for elevation and visibility, you will only
one output value for each input value. If you use an elevation and/or
visibility map as additional input (granted that the values in these
maps are not constants), you may get point clouds, i.e. several
different output values for the same input value if this input value
occurs more than once and either elevation or visibility differ
between the occurences.

Markus M

I'm using Grass 7 svn from about 2 weeks ago. The images are from the
Pantanal wetland in Brazil in the dry period (still lots of water
there). For 6S the settings are: Tropical atmosphere, continental
aerosol mode, 20km visibility.

Thanks and cheers
Daniel

On Fri, May 27, 2011 at 7:34 PM, Juan Benavides Duque <jbenavid@siu.edu> wrote:

I'm sending the code I used to run the i.atcorr module (including the
i.landsat.toar transformation)

(I also used the code sent by Yann Chemin (May 23) with the same results)

Of two files attached one has the code and other one the univariate stats
output of the band 1 TOAR raster for one of the 1986 scenes

A copy of the original landsat used have been placed temporarily at the
following location " assets "

hope somebody can help

thanks

juan

I'm using a desktop running Ubuntu 10.10 with a 64bit Intel(R) Core(TM) i7
CPU 860 @ 2.80GHz

2011/5/27 Gaspar Reyes Póndigo <gos47@hotmail.com>

I had same problem, i.atcorr not work with landsat 5TM band 1, 2 and
sometimes with band 3
I tried i.atcorr in different versions of grass, this is my results:

1. GRASS-6.4.1-2 under Mac Snow-Leopard 10.6.7: Not work band 1, 2, and
sometimes with band 3 (for years 1992, 1993, 1995 and 1997).
2. GRASS-6.5. revision 46428 compiled in Mac Snow-Leopard 10.6.7: Not work
band 1, 2, and sometimes with band 3 (for years 1992, 1993, 1995 and 1997)
3. GRASS-6.5svn45719(2011) under Microsoft Windows Xp sp3: All the bands
work,THIS IS VERY RARE

My images landsat 5 TM are from Tonameca, Oaxaca, México of years 1985 to
1999, and 2010 to 2011 (one image series for year), i am work with AOD and
visibility value, and convert manually DN to radiance (a).

(a) Lλ = [(LMAXλ − LMINλ) / (Qcalmax − Qcalmin)] (Qcal − Qcalmin) + LMINλ

Gaspar Reyes Póndigo
Universidad del Mar, Oaxaca, México
Campus Puerto-Ángel
Carretera principal Puerto Ángel Zipolite km 1.5
C.P. 70902

-------------------------------------------------------------------

Message: 1

Date: Fri, 27 May 2011 08:53:32 +0530

From: "Chemin, Yann (IWMI)" <Y.Chemin@cgiar.org>

Subject: RE: [GRASS-user] Re: i.atcorr returns all NULL values

To: "Juan Benavides Duque" <jbenavid@siu.edu>,

<grass-user@lists.osgeo.org>

Cc: Markus Metz <markus.metz.giswork@googlemail.com>, Elena Mezzini

<elena.mezzini@gmail.com>

Message-ID:

<001F233294EA894387CFDAADAB87DE25085063E9@iwmix.IWMI.CGIARAD.ORG>

Content-Type: text/plain; charset="us-ascii"

Hi Juan,

Can you please give the download link for your images,

Could you also check the output of i.landsat.toar for them and tell if

reflectance ranges are valid/logic.

Thank you,

Yann

From: Juan Benavides Duque [mailto:jbenavid@siu.edu]

Sent: Thursday, May 26, 2011 11:38 PM

To: Chemin, Yann (IWMI)

Cc: Markus Metz; Elena Mezzini

Subject: Re: [GRASS-user] Re: i.atcorr returns all NULL values

I tried Yann's code for the i.atcorr on some Landsat TM5 images

It worked very nice for images taken after 1995 but before that still

returns null values when running i.atcorr for bands 1 and 2

I used TM5 scenes from the same location for 1986, 1989, and 1996 and

the first two (1986 and 1989) had the same problem with the null

values...

sorry I can provide a way to fix it but I hope somebody will

juan c

On Tue, May 24, 2011 at 3:49 AM, Chemin, Yann (IWMI)

<Y.Chemin@cgiar.org> wrote:

Each created visibility map holds only one value r.mapcalc

expression="visibility=${vis_list[$i]}" --overwrite so why not just use

this visibility value as input in the >parameter file instead of

creating a map where all cells have the same value?

Yes, this is a valid point, the script is designed to (hopefully soon)

encompass raster maps of visibility data (maybe interpolated...), so

this is a placeholder for the next steps.

-----Original Message-----

From: Markus Metz [mailto:markus.metz.giswork@googlemail.com]

Sent: Tuesday, May 24, 2011 12:52 PM

To: Chemin, Yann (IWMI)

Cc: grass-user@lists.osgeo.org; Elena Mezzini; Markus Neteler

Subject: Re: [GRASS-user] Re: i.atcorr returns all NULL values

On Mon, May 23, 2011 at 9:36 PM, Markus Neteler <neteler@osgeo.org>

wrote:

Hi Yann,

On Mon, May 23, 2011 at 5:07 AM, Chemin, Yann (IWMI)

<Y.Chemin@cgiar.org> wrote:

p192 r030 image of July 2003 of Italy (L5TM) successfully corrected

for band 1 and 2.

The following script works well in GRASS GIS Trunk SVN.

(better send as attachment since a series of line breaks got broken)

...

# For i.atcorr scripting

#-----------------------------------------------------

vis_list=(10 10 8 9.7 15 8 7 10 10 9.7 12 9.7 7 12 12 12 3 15 12 9.7

6 15) vis_len=${#vis_list[*]} echo $vis_len

... this is not clear to me: why so many values and where do they

originate from? Since we have only 6 channels to work with...

Moreover, how can it be possible that visibility is different for

different channels of the same scene? From the documentation it seems

that visibility is related to aerosol concentration at 550nm which can

not possibility be different for different bands of the same scene.

Each created visibility map holds only one value r.mapcalc

expression="visibility=${vis_list[$i]}" --overwrite so why not just use

this visibility value as input in the parameter file instead of creating

a map where all cells have the same value?

Markus M

_______________________________________________

grass-user mailing list

grass-user@lists.osgeo.org

http://lists.osgeo.org/mailman/listinfo/grass-user

-------------- next part --------------

An HTML attachment was scrubbed...

URL: http://lists.osgeo.org/pipermail/grass-user/attachments/20110527/211bcf66/attachment-0001.html

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

7

I'll have to check but I believe I used constant visibility for the 6S
correction but, I did use an elevation map from SRTM. Of course the
area is rather flat (a wetland).

Daniel

On Tue, May 31, 2011 at 11:35 AM, Markus Metz
<markus.metz.giswork@googlemail.com> wrote:

On Sun, May 29, 2011 at 8:16 PM, Daniel Victoria
<daniel.victoria@gmail.com> wrote:

I'm also struggling with i.atcorr for Landsat. A friend of my
corrected some TM images using the Flash module in ENVI (based on
modtran) and I tried to correct the same images using 6S in grass
(i.atcorr). We both used the same radiance images that had some
problems with a few negative values in water areas. I set the negative
values to 0.

After correcting the TM images in Grass I created 6000 random point in
order to compare the images (flash vs. 6s). The attached graph shows
the density plot (~histogram) for each band (band 6 is actually TM
band7). For all images, value have been scaled from 0 to 1. Black line
is radiance, red is 6S and blue is flash. What we see is that for
bands 4, 5 and 7 there are no big differences but, for bands 1, 2 and
3, the correction done by flash is more pronounced.

Now, what I don't know:
1) Is this type of analysis (looking at the image histogram) OK?
2) Should atmospheric correction change the histogram?
3) For i.atcorr I get a sort of "linear" relation between radiance &
reflectance. That is, for each radiance there is only one value for
reflectance. But the flash correction gives a point cloud when I
compare radiance & reflectance (more than one reflectance value for
the same radiance). What is the expected behavior?

If you use global values for elevation and visibility, you will only
one output value for each input value. If you use an elevation and/or
visibility map as additional input (granted that the values in these
maps are not constants), you may get point clouds, i.e. several
different output values for the same input value if this input value
occurs more than once and either elevation or visibility differ
between the occurences.

Markus M

I'm using Grass 7 svn from about 2 weeks ago. The images are from the
Pantanal wetland in Brazil in the dry period (still lots of water
there). For 6S the settings are: Tropical atmosphere, continental
aerosol mode, 20km visibility.

Thanks and cheers
Daniel

On Fri, May 27, 2011 at 7:34 PM, Juan Benavides Duque <jbenavid@siu.edu> wrote:

I'm sending the code I used to run the i.atcorr module (including the
i.landsat.toar transformation)

(I also used the code sent by Yann Chemin (May 23) with the same results)

Of two files attached one has the code and other one the univariate stats
output of the band 1 TOAR raster for one of the 1986 scenes

A copy of the original landsat used have been placed temporarily at the
following location " assets "

hope somebody can help

thanks

juan

I'm using a desktop running Ubuntu 10.10 with a 64bit Intel(R) Core(TM) i7
CPU 860 @ 2.80GHz

2011/5/27 Gaspar Reyes Póndigo <gos47@hotmail.com>

I had same problem, i.atcorr not work with landsat 5TM band 1, 2 and
sometimes with band 3
I tried i.atcorr in different versions of grass, this is my results:

1. GRASS-6.4.1-2 under Mac Snow-Leopard 10.6.7: Not work band 1, 2, and
sometimes with band 3 (for years 1992, 1993, 1995 and 1997).
2. GRASS-6.5. revision 46428 compiled in Mac Snow-Leopard 10.6.7: Not work
band 1, 2, and sometimes with band 3 (for years 1992, 1993, 1995 and 1997)
3. GRASS-6.5svn45719(2011) under Microsoft Windows Xp sp3: All the bands
work,THIS IS VERY RARE

My images landsat 5 TM are from Tonameca, Oaxaca, México of years 1985 to
1999, and 2010 to 2011 (one image series for year), i am work with AOD and
visibility value, and convert manually DN to radiance (a).

(a) Lλ = [(LMAXλ − LMINλ) / (Qcalmax − Qcalmin)] (Qcal − Qcalmin) + LMINλ

Gaspar Reyes Póndigo
Universidad del Mar, Oaxaca, México
Campus Puerto-Ángel
Carretera principal Puerto Ángel Zipolite km 1.5
C.P. 70902

-------------------------------------------------------------------

Message: 1

Date: Fri, 27 May 2011 08:53:32 +0530

From: "Chemin, Yann (IWMI)" <Y.Chemin@cgiar.org>

Subject: RE: [GRASS-user] Re: i.atcorr returns all NULL values

To: "Juan Benavides Duque" <jbenavid@siu.edu>,

<grass-user@lists.osgeo.org>

Cc: Markus Metz <markus.metz.giswork@googlemail.com>, Elena Mezzini

<elena.mezzini@gmail.com>

Message-ID:

<001F233294EA894387CFDAADAB87DE25085063E9@iwmix.IWMI.CGIARAD.ORG>

Content-Type: text/plain; charset="us-ascii"

Hi Juan,

Can you please give the download link for your images,

Could you also check the output of i.landsat.toar for them and tell if

reflectance ranges are valid/logic.

Thank you,

Yann

From: Juan Benavides Duque [mailto:jbenavid@siu.edu]

Sent: Thursday, May 26, 2011 11:38 PM

To: Chemin, Yann (IWMI)

Cc: Markus Metz; Elena Mezzini

Subject: Re: [GRASS-user] Re: i.atcorr returns all NULL values

I tried Yann's code for the i.atcorr on some Landsat TM5 images

It worked very nice for images taken after 1995 but before that still

returns null values when running i.atcorr for bands 1 and 2

I used TM5 scenes from the same location for 1986, 1989, and 1996 and

the first two (1986 and 1989) had the same problem with the null

values...

sorry I can provide a way to fix it but I hope somebody will

juan c

On Tue, May 24, 2011 at 3:49 AM, Chemin, Yann (IWMI)

<Y.Chemin@cgiar.org> wrote:

Each created visibility map holds only one value r.mapcalc

expression="visibility=${vis_list[$i]}" --overwrite so why not just use

this visibility value as input in the >parameter file instead of

creating a map where all cells have the same value?

Yes, this is a valid point, the script is designed to (hopefully soon)

encompass raster maps of visibility data (maybe interpolated...), so

this is a placeholder for the next steps.

-----Original Message-----

From: Markus Metz [mailto:markus.metz.giswork@googlemail.com]

Sent: Tuesday, May 24, 2011 12:52 PM

To: Chemin, Yann (IWMI)

Cc: grass-user@lists.osgeo.org; Elena Mezzini; Markus Neteler

Subject: Re: [GRASS-user] Re: i.atcorr returns all NULL values

On Mon, May 23, 2011 at 9:36 PM, Markus Neteler <neteler@osgeo.org>

wrote:

Hi Yann,

On Mon, May 23, 2011 at 5:07 AM, Chemin, Yann (IWMI)

<Y.Chemin@cgiar.org> wrote:

p192 r030 image of July 2003 of Italy (L5TM) successfully corrected

for band 1 and 2.

The following script works well in GRASS GIS Trunk SVN.

(better send as attachment since a series of line breaks got broken)

...

# For i.atcorr scripting

#-----------------------------------------------------

vis_list=(10 10 8 9.7 15 8 7 10 10 9.7 12 9.7 7 12 12 12 3 15 12 9.7

6 15) vis_len=${#vis_list[*]} echo $vis_len

... this is not clear to me: why so many values and where do they

originate from? Since we have only 6 channels to work with...

Moreover, how can it be possible that visibility is different for

different channels of the same scene? From the documentation it seems

that visibility is related to aerosol concentration at 550nm which can

not possibility be different for different bands of the same scene.

Each created visibility map holds only one value r.mapcalc

expression="visibility=${vis_list[$i]}" --overwrite so why not just use

this visibility value as input in the parameter file instead of creating

a map where all cells have the same value?

Markus M

_______________________________________________

grass-user mailing list

grass-user@lists.osgeo.org

http://lists.osgeo.org/mailman/listinfo/grass-user

-------------- next part --------------

An HTML attachment was scrubbed...

URL: http://lists.osgeo.org/pipermail/grass-user/attachments/20110527/211bcf66/attachment-0001.html

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user