[gdal-dev] GSOC 2016

Fri Mar 25 00:17:59 PDT 2016

The deadline is today.

Sarthak

On Thu, Mar 24, 2016 at 1:52 AM, sarthak agarwal <sarthak0415 at gmail.com>
wrote:

> Hello Dmitry,
>
> I fixed the bug (I guess).
> Now coming to my proposal for GSoC, So I was thinking of working on
> project #4 *Auto-detection of EPSG codes from incomplete WKT.*
>
> What I understood from the project is that we need to predict the EPSG
> code of certain files on the basis of some attributes which are available
> in the file.
>
> The attributes can be extracted from the file for which I read this
> <http://www.gdal.org/osr_tutorial.html#querying_coordinate_system>.
>
> Now to solve this problem I thought a lot of methods but I think the best
> way to solve it will be using machine learning.
>
> The way ML will handle this problem is as follows-
>
>    1. We need to find the EPSG code for a file (testing data)
>    2. We have a file with some attributes (projections,datum,etc ).
>    3. We need to the guess the best suitable class for that file(EPSG)
>    4. Also, we have many files for which we know the attributes and the
>    corresponding class (training data).
>
> This problem is now translated into an ML problem which can be solved
> using the following models-
>
> 1. Bayesian Stastics <https://en.wikipedia.org/wiki/Posterior_probability>
>
> where,
> posteriror probability = probability of this file have EPSG code 'a'.
> prior probability = probability of occurence of EPSG code 'a'.
>
> likelihood probablity = cases where we saw such attributes when the EPSG
> code is 'a'.
>
>
> 2. or we can use a simple knn where k is the number of possible EPSG code
> and the dimension of the feature vector is the number of possible
> attributes. we need to the find a valid and promising weight function).
>
>
> 3. We can use multi-class SVM.
>
> 4. any other suggestion from the community regarding the possible choice
> of the algo.
>
> I am thinking of actually implementing all these algo(may add algo in
> future depending upon the suggestion) and select the algo which gives the
> best performance among all of them.
>
> Please provide me feedback on my proposal and suggestion if I can
> add/change anything.
> And since very less time is left in the deadline, I would like to convert
> it into proposal ASAP with your help.
>
> Regards,
> Sarthak
> 
>
> On Tue, Mar 22, 2016 at 8:09 PM, sarthak agarwal <sarthak0415 at gmail.com>
> wrote:
>
>> Hello Dmitry,
>>
>> I have made all the necessary changes and now the code is working as
>> expected ie If we provide no dbname, it will take the username by default.
>>
>> Here is the
>> https://github.com/OSGeo/gdal/commit/417f4ed2642c56729f93fdb959e2bf1b9f1fdfb1 to
>> the fix.
>>
>> Regards,
>> Sarthak
>> 
>>
>> On Tue, Mar 22, 2016 at 1:49 AM, Dmitry Baryshnikov <bishop.dev at gmail.com
>> > wrote:
>>
>>> Hi Sarthak,
>>>
>>> The problem is here
>>> https://github.com/sarthak-0415/gdal/blob/trunk/gdal/frmts/postgisraster/postgisrasterdriver.cpp#L78
>>>
>>> Your code produce situation there pszDbnameIn can be NULL. Before your
>>> fixes, that cannot be.
>>> So the line "CPLString osKey = pszDbnameIn;" produces crash.
>>>
>>> Don't wait for anybody with proposal. The new GSoC site is right place
>>> to discuss proposals.
>>>
>>> Best regards,
>>>     Dmitry
>>>
>>> 20.03.2016 19:41, sarthak agarwal пишет:
>>>
>>> Hello to all,
>>>
>>> Sorry for taking too long (exams and travelling).
>>>
>>> After running few tests -
>>>
>>>    - In my opinion, in Both the codes the error is not in
>>>    GetConnectionInfo function. if you replace return true with return
>>>    false at the last of the function it won’t fail in both cases.
>>>    - If you run this
>>>    <https://github.com/sarthak-0415/gdal/commit/3e037a84e3392841cda1b4b68d75d205118caa9d>
>>>    and this
>>>    <https://github.com/sarthak-0415/gdal/commit/26e9383645b177c9e4d2ca8798a3b662901f3b63>
>>>    code, it won’t give you the error, the value passed here are correct (NULL
>>>    if that’s the case with *ppszDbname, the error is somewhere else and
>>>    I am not able to debug it.)
>>>    - When I am trying to configure the gdal with enable-debug options
>>>    following error comes
>>>
>>>    make[1]: *** [gdalserver] Error 1
>>>    make[1]: *** Waiting for unfinished jobs....
>>>    /home/sarthak/gsoc2016/repos/gdal/gdal/.libs/libgdal.so: undefined reference to `CPLMutexHolder::CPLMutexHolder(_CPLMutex**, double, char const*, int, int)'
>>>    collect2: error: ld returned 1 exit status
>>>
>>>
>>> My current config options are
>>> ./configure --prefix=/home/sarthak/gsoc2016/repos/gdal/install/
>>> --with-python=yes -enabl-debug=yes
>>>
>>> the following error is for gdalServer gdalInfo gdal_translate and
>>> gdaladdo. All are having the same problem with undefined reference to
>>> `CPLMutexHolder::CPLMutexHolder(_CPLMutex**, double, char const*, int, int)'
>>>
>>> Please review the code and send me the feedback.
>>> Also, I would like to continue with the bug along with my GSoC proposal.
>>> For which I may have some ideas and would like to discuss the same with
>>> you.. can we talk on IRC since the deadline is in 5 days only.
>>>
>>> Regards,
>>> Sarthak
>>>
>>> On Wed, Mar 16, 2016 at 4:51 AM, Dmitry Baryshnikov <
>>> bishop.dev at gmail.com> wrote:
>>>
>>>> Hi Sarthak,
>>>>
>>>> The first version is not working (do you test it?):
>>>> <https://github.com/sarthak-0415/gdal/commit/36344cc26f23202cb289390322c1d295697136bd#diff-31df0e62d00ca09f9f11ad2f29e94b54R2541>
>>>> https://github.com/sarthak-0415/gdal/commit/36344cc26f23202cb289390322c1d295697136bd#diff-31df0e62d00ca09f9f11ad2f29e94b54R2541
>>>> Here you try to get array value with index -1. You need to set ppszDbname
>>>> = NULL no DB name present in input parameters.
>>>>
>>>> The second variant is not working too:
>>>> >>> ds = gdal.Open('PG:')
>>>> terminate called after throwing an instance of 'std::logic_error'
>>>>   what():  basic_string::_M_construct null not valid
>>>>
>>>> In both cases there is a problem here:
>>>> <https://github.com/sarthak-0415/gdal/blob/6264d3fc52242fdce858547cc3a0312b04fd638b/gdal/frmts/postgisraster/postgisrasterdataset.cpp#L2743>
>>>> https://github.com/sarthak-0415/gdal/blob/6264d3fc52242fdce858547cc3a0312b04fd638b/gdal/frmts/postgisraster/postgisrasterdataset.cpp#L2743
>>>>
>>>> Also look there ppszDbname is using, as before modifications the code
>>>> expect that ppszDbname cannot be NULL.
>>>>
>>>> Best regards,
>>>>     Dmitry
>>>>
>>>> 15.03.2016 13:13, sarthak agarwal пишет:
>>>>
>>>> Hey Dmitry ,
>>>> As discussed on the IRC yesterday,
>>>> I made the changes in the code.
>>>>
>>>> I build two versions of the code
>>>>
>>>>    1.
>>>>
>>>>    The changes suggested by you (to use the old trunk code and remove
>>>>    the additional checks) link
>>>>    <https://github.com/sarthak-0415/gdal/commit/36344cc26f23202cb289390322c1d295697136bd>
>>>>    travis <https://travis-ci.org/sarthak-0415/gdal/builds/116070409> .
>>>>    a. in this version the Dbname is left empty if not provided by the
>>>>    user.
>>>>    2.
>>>>
>>>>    The version in which we
>>>>    a. if the Dbname is provided by the user then ppzDbname=Dbname.
>>>>    b. else use the psql env var PGDATABASE
>>>>    c. else use the Username as the database name.
>>>>    d. if nothing is available then pass empty string.
>>>>    e link
>>>>    <https://github.com/sarthak-0415/gdal/commit/6264d3fc52242fdce858547cc3a0312b04fd638b>
>>>>    travis <https://travis-ci.org/sarthak-0415/gdal/builds/116055868>
>>>>
>>>> I think both version should work
>>>>
>>>> Regards,
>>>> Sarthak
>>>>
>>>> 
>>>
>>>
>>>
>>
>
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