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Messages - Karthikeyan L

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61
Programming / Block processing of image in MATLAB
« on: September 14, 2014, 06:52:32 PM »
There is a command called 'blockproc' that processes images (applies necessary computation) block wise (size of which has to be specified as input). Related documentation is provided in following link.
http://www.mathworks.in/help/images/ref/blockproc.html

I feel this saves lot of time in analysis of huge satellite images [with out this command it actually involves preparing windows and analysing each separately ('for' loops will be involved that eat lot of time)].

62
Models / Re: Curious case of Flood Frequency Analysis
« on: September 14, 2014, 06:38:46 PM »

63
Data / Re: SMOS Data
« on: September 09, 2014, 08:20:11 PM »
Sorry unable to upload them.
Okay I will use those commands and extract necessary region from .dbl files.

64
Data / Re: SMOS Data
« on: September 09, 2014, 08:11:38 PM »
Yes 10 simultaneous downloads is doing better job. Thank you.
These are actually zip files which contain two files .DBL and .HDR file. But the link you have sent has commands that deal with .nc files as input (syntax is indicating that). So, will these work on the above file formats I have mentioned?
I am attaching the files for reference.

65
Data / Re: SMOS Data
« on: September 09, 2014, 01:22:02 PM »
I am using FileZilla

66
Data / SMOS Data
« on: September 09, 2014, 12:52:49 PM »
Hi all,
I am trying to download SMOS L2 soil moisture data for India through two sources.
1) Their FTP server
2) Eoli-sa software
Both have issues, through FTP, the download speeds are very slow and also I have no option but to download for entire globe which is a constraint for me storage wise.
Through Eoli-sa (though I can download of India), I can download only 100 swath records at a time which will end up like 4000 5000 times for the total time period I need.

Can anyone pl let me know a better way of getting this data?

Thank you.

67
Post your question/information / Re: Soil Moisture Retrievals
« on: August 29, 2014, 02:40:21 PM »
Yes it took time for me to find information i need from ATBD but i think one can be sure on what is implemented exactly.
I will look for papers.

68
Post your question/information / Re: Soil Moisture Retrievals
« on: August 29, 2014, 01:02:29 PM »
I have found documentation (following link) pertaining to potential models, satellite data, ancillary data etc that will be used for SMAP mission.
https://smap.jpl.nasa.gov/science/dataproducts/ATBD/
I will look into the details on vegetation effects and downscaling.
Thank you for the post :)

69
Study material / Books related to mathematical modelling in MATLAB
« on: August 28, 2014, 06:43:00 PM »
I have found a bunch of books that explain mathematical concepts via MATLAB. Some of these include basics for MATLAB.
They may be helpful for wider audience.

Following link directs you to download rar file.

https://drive.google.com/file/d/0BxEtxgjULPpGa3dDQ2ZIaEhTVkk/edit?usp=sharing

70
Study material / Re: Radiative Transfer Theory
« on: August 28, 2014, 05:12:22 PM »
Okay I will read SMOS article. Thanks for your help.

71
Post your question/information / Soil Moisture Retrievals
« on: August 28, 2014, 04:58:55 PM »
Hi,
Can anyone comment on the scope of research in the area of satellite based soil moisture retrieval studies?

Thank you.

72
Study material / Re: Radiative Transfer Theory
« on: August 28, 2014, 04:53:53 PM »
Thank you.
I have read the radiative transfer model section of this article before.
What I felt is that there are slight inconsistencies in the models they are presenting in the articles.
Due to this, I was not able to zero in on what to understand.
This is the reason why I was asking if there are any books available on this topic. :)

73
Study material / Re: Radiative Transfer Theory
« on: August 28, 2014, 04:31:59 PM »
Thank you Sat Kumar.
I was actually searching for models related to AMSR-E data till now.
This article will be helpful.

74
Study material / Radiative Transfer Theory
« on: August 28, 2014, 03:59:55 PM »
Hi,
Can anyone suggest some books/articles concerning radiative transfer models for satellite based soil moisture retrieval studies?

Thank you,
Karthikeyan.

75
Models / Re: ANN - number of nodes and population size
« on: April 17, 2014, 07:52:20 PM »
Hi,
1) Number of data points:
I think in your case of sine waves, number of data points doesn't matter. During calibration, the network architecture should be trained in such a way that it would have understood the entire range of input data you are providing to it. When you are providing a sine wave, a series that covers entire range values of sine would be sufficient to train the network. Its like a simple regression model only. More you cover the range in calibration and make sure that your validation dataset (you can pick randomly) falls in this rage, you would end up getting decent results from ANN.
2) Number of nodes:
People are still working in this area to find out a method to decide optimum number of hidden neurons. You can take help from works by Prof. Sudheer from IIT Madras. To the extent of my knowledge, its all trial and error. But, you can take range of this number approximately between (number of inputs) to (2 times the number of inputs).
Pl note that along with number of nodes, network architecture and search algorithm influences the output significantly.
Hope I addressed your issue.

Regards,
Karthik.

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