[gdal-dev] reprojecting coastcolour (/meris) using python via GCPs

[Anton Korosov]

Hello Ivan,

ReprojectImage() has a parameter psOptions()
http://www.gdal.org/gdalwarper_8h.html#ad36462e8d5d34642df7f9ea1cfc2fec4
It should accept any of the warping options, e.g. '-tps'
http://www.gdal.org/gdalwarp.html

I'm not 100% sure (since I'm using Python) but it may work.


I'll take this chance also to promote Nansat, a scientist-friendly 
Python tool for working with satellite and model data:
Repo: https://github.com/nansencenter/nansat
Wiki: https://github.com/nansencenter/nansat/wiki
and API-rference: http://nansencenter.github.io/nansat/

It is a wrapper around GDAL, which adds scientific meaning to the opened 
images. Briefly: GDAL doesn't know much about e.g. band 22 in a MERIS 
image, Nansat does. It provides full information and allows simple 
usage, e.g.:
n = Nansat(meris_image)
n.reproject(dstDomain, tps=True)
n.export('outFile.nc')

It can open MERIS as well as tens of other formats.


Best regards!
Anton

On 02/17/2014 10:46 AM, Ivan Price wrote:
>
> Hello,
>
> I am trying to reproject a window inside a coastcolour (=MERIS) image. As far as I can see GDAL cannot read the coastcolour data directly, so i am reading the coastcolour netcdf in python, building a source dataset using the memory driver, adding GCPS (1 for every 10th pixel) and writing the data to it, then reprojecting the source dataset to a destination dataset which is a spatial subset of the original in wgs84 lat/long.
>
> This works fine and is relatively fast, but the reprojection is not accurate, the results are out by about 6-10 pixels (in various directions). On reading the forums it seems if i was using gdalwarp i would be using -tps, however the ReprojectImage() function does not seem to offer this parameter ? And i don't have the option of using the commandline tool as even gdal 1.10 cannot recognise the coastcolour data.
>
> So i guess i have 2 questions.. has anyone had any success reading coastcolour data with the gdal command line tools, and secondly:
>
> how can i get ReprojectImage() to be more accurate, given i have a GCP for every pixel ?
>
> thanks and regards,
>
> -ivan
>
>
>
>
>
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