[GRASS-dev] [grass-code I][470] i.atcorr: hardcoded input/output map names

GRASS GIS GRASS GIS developer
1

BTW, the links to 6s manuals in i.attcor man page are 404 not found.

Maciek

2

Yes, this is certainly my (late) Univ website...
Originals are still available with me to whom wants to have/host.

On Tuesday 28 August 2007 23:57:05 Maciej Sieczka wrote:

BTW, the links to 6s manuals in i.attcor man page are 404 not found.

Maciek

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3

Also, there are contrary statements about the units of 'ialt' elevation
raster:

"Input altitude map in m"

and few lines further:

"The elevation values should be in km."

Maciek

4

Also, please explain if/how the elevation and visibility rasters (ialt
and ivis) interefere with the target elevation and visibility
parameters in the icnd configuration file. For example, if I use ialt
raster, do I still have to/must not provide the target elevation in the
config file?

Maciek

5

And propably the last thing - there are 8 parameters to define in the
i.attcor config file, while "6S CODE PARAMETER CHOICES" section
mentions only 6 (A-F). How do I understand it?

Maciek

6

Hello Maciej,

This is the testdata config file for 6S on GRASS.

Yann

On Wednesday 29 August 2007 01:15:44 Maciej Sieczka wrote:

Also, there are contrary statements about the units of 'ialt' elevation
raster:

"Input altitude map in m"

and few lines further:

"The elevation values should be in km."

Maciek

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Yann Chemin
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Sainte-Anne d'Auray, France

(attachments)

ETM4_atmospheric_input_GRASS.txt (562 Bytes)

7

Hi Maciek,

i.atcorr is in fact the translation from F to C of 6S model.
Down there are info about it.

6s download sites (have manuals and GUI too):
http://www-loa.univ-lille1.fr/Msixs/msixs_gb.html
http://www.ltid.inpe.br/dsr/mauro/6s/
http://modis-sr.ltdri.org/6S_code/index.html

article:
http://ieeexplore.ieee.org/iel1/36/12630/00581987.pdf?tp=&isnumber=12630&arnumber=581987&type=ref

Enjoy,
Yann

On Wednesday 29 August 2007 01:27:46 Maciej Sieczka wrote:

Also, please explain if/how the elevation and visibility rasters (ialt
and ivis) interefere with the target elevation and visibility
parameters in the icnd configuration file. For example, if I use ialt
raster, do I still have to/must not provide the target elevation in the
config file?

Maciek

_______________________________________________
grass-dev mailing list
grass-dev@grass.itc.it
http://grass.itc.it/mailman/listinfo/grass-dev

--
Yann Chemin
http://airdensity.hi5.com/
Sainte-Anne d'Auray, France

8

Hello again,

Altitude (DEM) input in GRASS module is in meters
Internally 6S ingests altitude data in Km, check line 274 of main.cpp

Yann

On Wednesday 29 August 2007 01:15:44 Maciej Sieczka wrote:

Also, there are contrary statements about the units of 'ialt' elevation
raster:

"Input altitude map in m"

and few lines further:

"The elevation values should be in km."

Maciek

_______________________________________________
grass-dev mailing list
grass-dev@grass.itc.it
http://grass.itc.it/mailman/listinfo/grass-dev

--
Yann Chemin
http://airdensity.hi5.com/
Sainte-Anne d'Auray, France

9

Yann wrote:

i.atcorr is in fact the translation from F to C of 6S model.
Down there are info about it.

6s download sites (have manuals and GUI too):
http://www-loa.univ-lille1.fr/Msixs/msixs_gb.html
http://www.ltid.inpe.br/dsr/mauro/6s/
http://modis-sr.ltdri.org/6S_code/index.html

article:
http://ieeexplore.ieee.org/iel1/36/12630/00581987.pdf?tp=&isnumber=12630&arnumber=581987&type=ref

Yann,

Thanks for the reply but I don't see how it answers this particular
question, quoted below. The question is GRASS's i.attcor specific. 6s
manuals don't cover it:

On Wednesday 29 August 2007 01:27:46 Maciej Sieczka wrote:

Also, please explain if/how the elevation and visibility rasters (ialt
and ivis) interefere with the target elevation and visibility
parameters in the icnd configuration file. For example, if I use ialt
raster, do I still have to/must not provide the target elevation in the
config file?

Maciek

10

Yann wrote:

On Wednesday 29 August 2007 01:15:44 Maciej Sieczka wrote:

Also, there are contrary statements about the units of 'ialt' elevation
raster:

"Input altitude map in m"

and few lines further:

"The elevation values should be in km."

This is the testdata config file for 6S on GRASS.

I mean that the i.attcor manual gives contrary descriptions of what
units the elevation raster should be.

Maciek

11

Yann wrote:

On Wednesday 29 August 2007 01:15:44 Maciej Sieczka wrote:

Also, there are contrary statements about the units of 'ialt'
elevation raster:

"Input altitude map in m"

and few lines further:

"The elevation values should be in km."

Altitude (DEM) input in GRASS module is in meters

Internally 6S ingests altitude data in Km, check line 274 of main.cpp

Ok, I'll fix the manual accordingly.

Maciek

12

Hi Maciek:

Line 221-222 in main.cpp:

ialt_fd: height map file descriptor, negative if global value is used
ivis_fd: visibility map file descriptor, negative if global value is used

Yann

On Wednesday 29 August 2007 01:27:46 Maciej Sieczka wrote:

Also, please explain if/how the elevation and visibility rasters (ialt
and ivis) interefere with the target elevation and visibility
parameters in the icnd configuration file. For example, if I use ialt
raster, do I still have to/must not provide the target elevation in the
config file?

Maciek

_______________________________________________
grass-dev mailing list
grass-dev@grass.itc.it
http://grass.itc.it/mailman/listinfo/grass-dev

--
Yann Chemin
http://airdensity.hi5.com/
Sainte-Anne d'Auray, France

13

Hello again Maciek,

You are referring to the config file (as example below from help file):
1) -> 8 (Landsat ETM+ geometrical conditions)
2) -> 2 19 13.00 -47.410 -20.234 (month,day,hh.ddd,long.,lat.) (hh.ddd=the
decimal hour in universal time)
3) -> 1 (tropical atmospheric mode)
4) -> 1 (continental aerosols model)
5) -> 15 (visibility in km (aerosol model
concentration)
6) -> -.600 (target at 600 m above sea level)
7) -> -1000 (sensor on board of satellite)
8) -> 64 (fourth band of ETM+ Landsat 7)

As far as I can see, the documentation deal with:
A) Geometrical conditions (ref. to #1)
B) Atmospheric model (ref. to #3)
C) Aerosols model (ref. to #4)
D) Aerosol model concentration (ref. to #5)
E) Target altitude sensor platform (ref. to #6)
F) Sensor band (ref. to #8)

Missing detailed descriptions are for:
#2) This is Sensor overpass details (in image header generally)
#7) This is less known to me since it is specifying the type of sensor, in
this case (as all of my work) it is a satellite platform holding the sensor.
I guess there is another value for airborne sensors, and this can be found in
the 6S manual.

Yann

On Wednesday 29 August 2007 01:49:53 Maciej Sieczka wrote:

And propably the last thing - there are 8 parameters to define in the
i.attcor config file, while "6S CODE PARAMETER CHOICES" section
mentions only 6 (A-F). How do I understand it?

Maciek

_______________________________________________
grass-dev mailing list
grass-dev@grass.itc.it
http://grass.itc.it/mailman/listinfo/grass-dev

--
Yann Chemin
http://airdensity.hi5.com/
Sainte-Anne d'Auray, France

14

Yann wrote:

Hi Maciek:

Line 221-222 in main.cpp:

ialt_fd: height map file descriptor, negative if global value is
used ivis_fd: visibility map file descriptor, negative if global
value is used

Yann,

Thanks. I don't know C. I'm no programmer. Can you please say which one
- the raster or the value in the i.attcor config file takes precedence?
What happens if both are specified?

Maciek

15

Yann wrote:

You are referring to the config file (as example below from help file):
1) -> 8 (Landsat ETM+ geometrical conditions)
2) -> 2 19 13.00 -47.410 -20.234 (month,day,hh.ddd,long.,lat.) (hh.ddd=the
decimal hour in universal time)
3) -> 1 (tropical atmospheric mode)
4) -> 1 (continental aerosols model)
5) -> 15 (visibility in km (aerosol model
concentration)
6) -> -.600 (target at 600 m above sea level)
7) -> -1000 (sensor on board of satellite)
8) -> 64 (fourth band of ETM+ Landsat 7)

As far as I can see, the documentation deal with:
A) Geometrical conditions (ref. to #1)
B) Atmospheric model (ref. to #3)
C) Aerosols model (ref. to #4)
D) Aerosol model concentration (ref. to #5)
E) Target altitude sensor platform (ref. to #6)
F) Sensor band (ref. to #8)

Missing detailed descriptions are for:
#2) This is Sensor overpass details (in image header generally)
#7) This is less known to me since it is specifying the type of sensor, in
this case (as all of my work) it is a satellite platform holding the sensor.
I guess there is another value for airborne sensors, and this can be found in
the 6S manual.

Thanks. I'm slowly understanding how this all works and I've been
updating/fixing the manual step by step for the last past hours. I'm
going to commit it after sorting out few remaining things:

1. The example parameters file you quote says that ".-600" in line 6
means "target at 600 m ASL". However, in the i.attcor documentation,
section E of "6S CODE PARAMETER CHOICES" says: "xps <=0. means the
target is at the sea level". This is contrary. Can you please explain?

2. Section E - I'm not sure if the "-100< xpp <0" shouldn't actually be
"-1000< xpp <0". ?

3. What is the "iaer" that section D refers to?

4. BTW section D - what "Aerosol model concentration" is supposed to
mean? As it is now, it means, other words, "a concentration of the
aerosol model", which doesn't make sense IMHO. What should I change it to?

Maciek

16

If using a global value in the configuration file, then it is overiding the
corresponding input map.

I have not yet found a clear explaination on what to do in the config file to
read the map directly. Careful though, since reading input maps will run 6s
for each pixel (0.5-1s/pixel can be a long time for a Landsat image to
process).

Using global values from config file will run 6s once and apply an affine
transform on all the image. Fast and OK for a small area.

trade-off...

On Thursday 30 August 2007 02:49:13 Maciej Sieczka wrote:

Yann wrote:
> Hi Maciek:
>
> Line 221-222 in main.cpp:
>
> ialt_fd: height map file descriptor, negative if global value is
> used ivis_fd: visibility map file descriptor, negative if global
> value is used

Yann,

Thanks. I don't know C. I'm no programmer. Can you please say which one
- the raster or the value in the i.attcor config file takes precedence?
What happens if both are specified?

Maciek

--
Yann Chemin
http://airdensity.hi5.com/
Sainte-Anne d'Auray, France