[gdal-dev] [Proj] Pixel Shifts When Warping

[Yuta Sato]

Dear all:

Thanks for sharing your ideas and experiences.

As I mentioned in my question, it seems that MRT result is shifting right
while the GDAL warp result is correct. Do you agree?

The exact upper left corner of the original HDF-EOS file is exactly as the
GDAL warpped result.

The HDF file uses top left corner of top left pixel, while the MRT seems to
use central of top left pixel (MRT userguide page 10 under corner
coordinates section), am I right?

https://lpdaac.usgs.gov/sites/default/files/public/mrt41_usermanual_032811.pdf

If I am right, fortunately the GDAL would win!





On Mon, May 18, 2015 at 11:24 PM, Markus Neteler <neteler at osgeo.org> wrote:

> On Sun, May 17, 2015 at 1:32 PM, Even Rouault
> <even.rouault at spatialys.com> wrote:
> > Le dimanche 17 mai 2015 12:54:44, Markus Neteler a écrit :
> >> On Sun, May 17, 2015 at 6:44 AM, Yuta Sato <yutaxsato at gmail.com> wrote:
> >> > Dear GDAL and Proj Developers and Users:
> >> >
> >> > I am really frustrated when the MODIS HDF file converted into GeoTiff
> >> > with GCS projection never match with the same MODIS file  converted
> from
> >> > MODIS Reprojection tool.
> >>
> >> We had this issue in the past, too, for our "EuroLST" project
> >> (gap-filling of all LST maps for Europe, see
> http://gis.cri.fmach.it/eurolst/).
> >> Solved since then, see below.
> >> ...
> >>
> >> > Do you have any idea on which is more precise: gdalwarp or MRT? Or
> there
> >> > is any way in gdalwarp to get the same image as MRT gives?
>
> An addition:
>
> For our EuroLST project we use EU LAEA as target projection. In our
> tests (we made a lot) the MRT results came out shifted by 0.5 -1.0
> pixel since MRT does not support a datum or ellipsoid for LAEA (LA in
> MRT), instead it supports only a sphere when reprojecting from MODIS
> sinusoidal.
>
> Using recent GDAL, gdalwarp does the reprojection from MODIS
> sinusoidal to EU LAEA correctly.
>
> >> You may take a look at
> >> http://pymodis.fem-environment.eu/
> >>
> >> pyModis >= 1.0 comes with fast GDAL support (way faster than MRT).
> >>
> >> The details of the gdalwarp usage you find in the source code here:
> >>
> https://github.com/lucadelu/pyModis/blob/master/pymodis/convertmodis_gdal.py
> >
> > Markus,
> >
> > for the sake of my curiosity, could you explain what specific stuff it
> does
> > compared to gdalwarp ? I quickly skimmed through the file and only saw
> regular
> > use of the GDAL warping API. But perhaps I missed something.
>
> pyMODIS is a set of scripts and a library to perform the download of
> large numbers of MODIS HDF/XML files (think cronjob), it creates a
> mosaic of several tiles, it extracts specific information from
> bit-encoded MODIS quality assessment layers of different product types
> etc.
>
> Essentially a ready to use product which happily uses GDAL as a backend.
>
> Markus
>
> --
> http://courses.neteler.org
> http://gis.cri.fmach.it/neteler/
> http://grass.osgeo.org
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/gdal-dev/attachments/20150519/ae1e2581/attachment.html>