[gdal-dev] Re: GDAL drivers written in Python

[Knut-Frode Dagestad]

Thank you for useful comments, Antonio.

I agree with you that the ideal thing would be to improve the support of 
GDAL for our satellite data formats of interest. It would be great if we 
could combine efforts and get some momentum on this.

Several formats (e.g. TerraSAR-X, Envisat ASAR, MERIS and AATSR) are 
read, but not georeferenced. To my understanding this must be due to 
bugs in the drivers, as listed in some tickets (#3709, #3160)
Since Radarsat-2 is georeferenced, I assume it should also be possible 
to georeference other formats which are not projected, but have only 
many GCPs.
I tried the Alos/Palsar driver, but it did not seem to work at all. The 
drivers are also rather minimalistic, and does e.g. not read the Doppler 
Grid of Envisat ASAR. However, from your answer, I assume it is 
straightforward to read such kind of extra data with supplementary 
Python code. I am also not sure how easy it is to get support and 
geocoding for range-projected Single Look Complex data(?)
Finally, we would also ideally like to have immediate (pre release) 
support for upcoming satellites such as the ESA Sentinel satellites.

We consider a solution to use ESA Beam and NEST Java APIs for additional 
readers. But it is getting a bit messy to mix Python, C and Java in a 
multi-platform environment (Linux, Mac and Windows).

Best regards from Knut-Frode



On 06.04.2011 10:13, Antonio Valentino wrote:
> Hi Knut-Frode,
>
> Il giorno Wed, 06 Apr 2011 09:51:42 +0200
> Knut-Frode Dagestad<knutfrodesoppel at hotmail.com>  ha scritto:
>
>> Hi,
>>
>> Our group is looking at the possibility to use GDAL with Python
>> bindings for our work with satellite data. One limitation seems
>> however to be missing/incomplete drivers, as we have no capacity to
>> implement new drivers in C.
>
> It would be interesting to know which are the missing formats and the
> missing features in existing drivers.
> I use GDAL Python bindings to read satellite data of SAR missions and
> I'm very interested GDAL to have the best possible support for this
> kind of data.
> So maybe I could help in some way if you provide some more info.
>
>> It seems however to me that the Python API allows to create GDAL
>> Datasets from data which in principle could be read by any non-GDAL
>> functions, e.g. PyHDF or self-made Python readers.
>
> Yes, correct
>
>> My question is therefore: is there in principle any important
>> differences or limitations with datasets created this way, compared
>> to datasets read with native GDAL drivers?
>>
>> Best regards from Knut-Frode
>
> GDAL dataset are an abstraction of the real datasets on file so, once
> created, there is no difference between datasets.
>
> IMHO, also depending on the version of GDAL you, python bindings
> could miss some function that is present in the C/C++ API so creating a
> new dataset from scratch with the Python API could be a little harder
> in some very particular case.
>
> regards
>