[Gdal-dev] gdal_grid: Comments from a new player

[Fodder]

Thanks Frank for your reply,

- One more thing I've noticed. The 'nearest' interpolation algorithm doesn't
seem to accept the defaults of 0 (meaning whole array) for radius1 & radius
2, when used like this:

gdal_grid -a nearest:radius1=0.0:radius2=0.0:angle=0.0:nodata=-1000000000
-txe ...

it generates a grid full of nodata values. I have to set it to:

gdal_grid -a
nearest:radius1=10000000:radius2=1000000:angle=0.0:nodata=-1000000000 -txe

to get a correct Theisson Polygon style interpolation.

Cheers


Frank Warmerdam-2 wrote:
> 
> Fodder wrote:
>> Hi All,
>> 
>> Just a few things I've noticed since I've been playing around with
>> gdal_grid
>> (I'm using the vrt/csv driver):
>> 
>>    - It's important to put the whole path of the csv file in the vrt file
>> (even if they're in the same directory) if you are running gdal_grid.exe
>> from a different locaion.
> 
> Fodder,
> 
> I believer there is a "relativeToVRT" attribute on the filename element
> in the VRT file that can be set to 1 (or TRUE) if you want the path to
> be interpreted as relative to the vrt file.
> 
>>    - With the EHdr output format, it seem to be necessary to switch the
>> YMin
>> & YMax around in the -tye parameter. The YMin value seems to be used for
>> the
>> ULYMap tag in the .hdr file. Is this a bug?
> 
> no idea.
> 
>>    - A lat/long WGS projection reference seems to be added to the grid if
>> no
>> projection string is passed. I would have thought that a blank projection
>> or
>> non-earth projection would be better.
> 
> no idea.
> 
>> Finally, a question, to integrate this with a windows app, how do I know
>> when gdal_grid is finished? Can I test for the existance of the output
>> file
>> with certain permissions or could this lead me astray?
> 
> Depending on how you launch he subprocess there should be a variety of
> ways of
> testing if the process is complete.  You can't be confident that the file
> is
> completely written till the gdal_grid process terminates.
> 
> Best regards,
> -- 
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | President OSGeo, http://osgeo.org
> 
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/gdal-dev
> 
> 

-- 
View this message in context: http://www.nabble.com/gdal_grid%3A-Comments-from-a-new-player-tp17591913p17592248.html
Sent from the GDAL - Dev mailing list archive at Nabble.com.