[GRASS-dev] MODIS import in GRASS6.4

[Markus Neteler]

On Thu, Feb 18, 2010 at 4:38 PM, Franz Schiller
<franzschiller1975 at gmail.com> wrote:
>
>
> I have been using MODIS datasets in MRT tool and MATLAB but Now I want to
> import MODIS projected datasets to GRASS .
>
> At http://grass.osgeo.org/wiki/MODIS is described methods to do this. But I
> have a few (quick) questions. Thanks for your help

Quick questions yes, but not so easy to answer!


>  Question 1: can those methods be applied using a GRASS Script? (I believe
> so)

yes and no: I use MRT in batch mode within a GRASS script. Not sure
if this answers your question.

> Question 2: in method 1 (http://grass.osgeo.org/wiki/MODIS#Method_1), It’s
> said to create a Project/mapset with EPSG 3266. Why that system? And Why if
> gdal_translate will create geotiff in EPSG4326?

I personally stick with
http://grass.osgeo.org/wiki/MODIS#Method_0
The gdal way is too messy for me.

> Question 3: Regarding a_ullr. This flag asks for Upperleft and lowerright.
> This means that those values are the same for all files. But in the case
> that they may vary. How can I obtain them from MODIS Metadata/header?

They should be in the XML file.

> And
> this would mean that the we are dealing with a regular dataset because in a
> Geostationary dataset this wouldn’t be possible (I guess).

Geostationary (Terra and Aqua are polar orbiting)? not sure what you mean.

> Question 4: What is the –co flag? I read Gdal_translate description but I
> didn’t find it very clear..

-co: compression of resulting file

Feel free to improve the Wiki page.

> Question 5: As far as I can see, Geotiff format is used as an intermediate
> format in order to import data to GRASS. Why is it chosen?

Because it is well known. You can chose whatever you like and works.

> Question 6: Since GDAL does not automatically georeference HDF4 images, is
> there a list of the formats that GDAL automatically georreference?

Yes:
http://www.gdal.org/formats_list.html

> Question 7: if we define a_ullr, this means that GCP points are not being
> used right?

I have no idea (since I prefer MRT).

> Regarding method 2, that is based on GRASS6.5, will this be implemented for
> grass 6.4? (the –i flag)

I guess in 6.4.1 if it can be backported.

Markus