[GRASS-user] i.atcor and Py6S

GRASS GRASS user
1

Hi everyone,

I have a couple of questions with regard to i.atcor:

  1. Unless I am mistaken, GRASS uses its own implementation of the 6S algorithm. Is that accurate?
  2. If it is, which version of the 6S algorithm has been implemented?
  3. Has anyone used Py6S in order to create an input file for i.atcor? Py6S is compatible with 6S version 1.1

with kind regards,
Panos

2

On 09/11/15 18:11, Panagiotis Mavrogiorgos wrote:

Hi everyone,

I have a couple of questions with regard to i.atcor:

1. Unless I am mistaken, GRASS uses its own implementation of the 6S
algorithm. Is that accurate?

Yes.

2. If it is, which version of the 6S algorithm has been implemented?

I don't think that the basic algorithm was changed since its origin in beginning 2003, so I would think its V1.

Moritz

3

On Thu, Nov 12, 2015 at 10:30 AM, Moritz Lennert <
mlennert@club.worldonline.be> wrote:

On 09/11/15 18:11, Panagiotis Mavrogiorgos wrote:

2. If it is, which version of the 6S algorithm has been implemented?

I don't think that the basic algorithm was changed since its origin in
beginning 2003, so I would think its V1.

Moritz

Hi Moritz,

thank you for your reply.

Just for info, according to the website:

The lastest version of the code 6S (6SV2.1), released in June 2015, is

now available to download here <http://6s.ltdri.org/pages/downloads.html&gt;\.

Moreover, as far as I can tell, the input file of the current version
supports additional arguments. E.g.:

2 1 0.5 (Target reflect., environ. reflect., target radius (km))
1 (Request for atmospheric correction)
-0.1 (Parameter of the atmospheric correction)
4 (Ground surface is not polarized)

For more info you can check the part 1 of the manual
<http://6s.ltdri.org/pages/manual.html&gt; (page 52)

4

Panagiotis Mavrogiorgos wrote:

> Hi everyone,
> I have a couple of questions with regard to i.atcor:
> 1. Unless I am mistaken, GRASS uses its own implementation of the 6S
> algorithm. Is that accurate?

Moritz Lennert:

Yes.

> 2. If it is, which version of the 6S algorithm has been implemented?

I don't think that the basic algorithm was changed since its origin in
beginning 2003, so I would think its V1.

Moritz, did you confirm that? I think Yann has re-worked some bits, if
I am not wrong (no time to confirm myself too :-/).

Nikos

5

On 12/11/15 10:31, Nikos Alexandris wrote:

Panagiotis Mavrogiorgos wrote:

Hi everyone,
I have a couple of questions with regard to i.atcor:
1. Unless I am mistaken, GRASS uses its own implementation of the 6S
algorithm. Is that accurate?

Moritz Lennert:

Yes.

2. If it is, which version of the 6S algorithm has been implemented?

I don't think that the basic algorithm was changed since its origin in
beginning 2003, so I would think its V1.

Moritz, did you confirm that? I think Yann has re-worked some bits, if
I am not wrong (no time to confirm myself too :-/).

Pretty sure: https://trac.osgeo.org/grass/log/grass/trunk/imagery/i.atcorr

Moritz