[gdal-dev] Problems with GDAL_GRID

[Dave Burkholder]

As requested by Even, I downloaded the latest Version 2.3.2 of GDAL_GRID and ran it with the same data. I have attached an image comparing the results for 3 different versions of GDAL_GRID. The results seem to be regressing!

Up until the latest 2.3.2 version, the results compared very nicely with the ArcGIS interpolation model except for the 'NoData glitches'.

If anyone is interested, I could share the CSV and VRT input files as a 188KB zip-file. The input is typical of our single-beam echo-sounder bathymetric (underwater) data with detailed cross-sections (points every 0.35 metres) at approximately 100 m intervals down the river. Our typical cell size is 5m x 5m.

Hoping to get some response. Thanks in advance.

Regards, Dave

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Date: Fri, 05 Oct 2018 12:22:53 +0200
From: Even Rouault <even.rouault at spatialys.com>
To: gdal-dev at lists.osgeo.org
Cc: Dave Burkholder <DBurkholder at nhcweb.com>
Subject: Re: [gdal-dev] Problems with GDAL_GRID
Message-ID: <2240094.MaNDqafY3D at even-i700>
Content-Type: text/plain; charset="us-ascii"

Dave,

you might want to try with the latest GDAL 2.3.2
There has been a bug fixed in that one that could potentially fix the issue 
you have:
https://github.com/OSGeo/gdal/issues/638

Even

> I am hoping that someone receiving this email might be able to help me or
> direct me to someone else who can. Please excuse me if this is an
> inappropriate use of your mailing list or attachment format.
> 
> I am attempting to use GDAL_GRID with linear interpolation to generate a
> TIF-file and polygonized SHP-file, from a TXT-file of 3D point data
> generated by a single-beam echo-sounder which collects detailed river
> cross-sections typically at every 50 - 100 m intervals down a river.
> 
> We currently have a database of over 2100 bathymetric (underwater) surveys
> and have been successfully using an ArcGIS macro, but for a number of
> reasons I was hoping to migrate away from ArcGIS and use GDAL_GRID instead
> for batch input. The point data files work fine in both QGIS and ArcGIS,
> but not in GDAL_GRID. I am continuously getting 'blocks' of random 'No
> Data'-areas in my output (refer to attachment). I am wondering if this is a
> flaw in the GDAL_GRID program or if I am not using it correctly, and
> whether there is an alternative program that might be more stable.
> 
> I have prepared a PDF file which documents and summarizes the problem if
> anyone is interested.
> 
> Any advise you might be able to give me would be MUCH appreciated!
> 
> Thank you in advance.
> 
> Regards, David Burkholder


-- 
Spatialys - Geospatial professional services
http://www.spatialys.com


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