[gdal-dev] tps - gdalwarp vs ogr2ogr

[Stijn Tallir]

Hi Jukka,

The transformation lasted 3h20min vs 9min (before the fix)!

The results for raster and vector tps transformation are very similar now
and nothing changed for the vector result. Do I have to conclude the
previous rasters tps transformation method was faulty then?

Stijn

Op ma 6 nov 2023 om 16:32 schreef Stijn Tallir <stijn+gdal-dev at strict.be>:

> Hi,
>
> Does that mean the old raster tps transformation was "wrong" or the old
> vector transformation?
>
> I'm doing a test and trying to transform my raster image with the latest
> dev version in osgeo4W but it takes forever to process now. Don't know in
> how many days I will see the result :(
>
> The vector transformation with the latest dev version was the same (time
> and result).
>
> Stijn
>
> Op ma 6 nov 2023 om 14:48 schreef Rahkonen Jukka <
> jukka.rahkonen at maanmittauslaitos.fi>:
>
>> Hi,
>>
>>
>>
>> See the issue https://github.com/OSGeo/gdal/issues/8572. Maybe your
>> problem is also resolved by https://github.com/OSGeo/gdal/pull/8573. The
>> fix is included in the GDAL 3.8 RC1 version that was released 3 hour ago.
>> Do you have an option to make a test?
>>
>>
>>
>> -Jukka Rahkonen-
>>
>>
>>
>> *Lähettäjä:* Stijn Tallir <stijn at strict.be>
>> *Lähetetty:* maanantai 6. marraskuuta 2023 14.47
>> *Vastaanottaja:* Rahkonen Jukka <jukka.rahkonen at maanmittauslaitos.fi>
>> *Kopio:* gdal-dev at lists.osgeo.org
>> *Aihe:* Re: [gdal-dev] tps - gdalwarp vs ogr2ogr
>>
>>
>>
>> Hi Jukka,
>>
>>
>>
>> I finally found the time to produce a test set.
>>
>>
>>
>> You can download it here:
>> https://drive.google.com/file/d/1Y08Q-tIm5dxyKFKNdVqilvAO3H7FFFbx/view?usp=sharing
>>
>>
>>
>> I started from an unreferenced raster file (raster2tps.tif) with gcp's
>> (gcp4tps.gcp) and transformed it with tps (tpsraster.tif).
>>
>> Then polygonized the unreferenced raster file (vector2tps.shp) and
>> transformed the result with  the same gcp's (gcp4tps.gcp) and with tps
>> (tpsvector.shp).
>>
>>
>>
>> The vector2tps.shp polygons are "flipped" because of the different
>> Y-origin for rasters and vectors but this way both datasets can use the
>> exact same gcp's.
>>
>>
>>
>> When you lay the tpsvector-result on top of the tpsraster-result (in QGis
>> for instance) you'll see the differences in how both are transformed.
>>
>>
>>
>> Kind regards,
>>
>>
>>
>> Stijn
>>
>>
>>
>>
>>
>>
>>
>> Op wo 16 aug 2023 om 13:16 schreef Stijn Tallir <stijn+gdal-dev at strict.be
>> >:
>>
>> Yes, I checked them visually for both raster and vector.
>>
>>
>>
>> I compared the results also visually. The rasters are transformed in a
>> way that the end ponts of the gcp's align exactly with the result so that
>> is why I referred to it as "right". The vector data result is in the
>> neighbourhood of the end points (sometimes a rather significant distance).
>>
>>
>>
>> The result is different from order 1-3 transformations so I presume the
>> tps option isn't ignored.
>>
>>
>>
>> Stijn
>>
>>
>>
>> Op wo 16 aug 2023 om 11:52 schreef Rahkonen Jukka <
>> jukka.rahkonen at maanmittauslaitos.fi>:
>>
>> Hi,
>>
>>
>>
>> Did you check the ground control points? What is your reference when you
>> say that one result is right, and another wrong? Have you used some other
>> software for comparison? Or do you only know that the results are different?
>>
>>
>>
>> -Jukka-
>>
>>
>>
>> *Lähettäjä:* Stijn Tallir <stijn at strict.be>
>> *Lähetetty:* keskiviikko 16. elokuuta 2023 12.27
>> *Vastaanottaja:* Rahkonen Jukka <jukka.rahkonen at maanmittauslaitos.fi>
>> *Kopio:* gdal-dev at lists.osgeo.org
>> *Aihe:* Re: [gdal-dev] tps - gdalwarp vs ogr2ogr
>>
>>
>>
>> Hi Jukka,
>>
>>
>>
>> I thought of the density as an option for the "error" as you suggested
>> and I made a point-file with a point for every pixel in my original image
>> and used this as a source for the ogr2ogr transformation. So you could say
>> the desnity for both sources raster and vector) are then alike.
>>
>>
>>
>> The results were still the same (and wrong) ...
>>
>>
>>
>> Stijn
>>
>>
>>
>>
>>
>> Op wo 16 aug 2023 om 10:22 schreef Rahkonen Jukka <
>> jukka.rahkonen at maanmittauslaitos.fi>:
>>
>> Hi,
>>
>>
>>
>> Without test data it is very hard to say much. I believe that the promise
>> of tps is that the ground control points stay where they are set. The
>> intermediate points follow the least tension surfaces and I do not know how
>> exactly those spline algorithms are defined. Raster data is full of points
>> to warp but probably in the vector data the transformation is done vertex
>> by vertex. I would first check if the GCPs are in the same place in both
>> outputs. Then I would make a test by densifying the vector data before
>> georeferencing to have much more vertices and see if it has any effect on
>> the result.
>>
>>
>>
>> -Jukka Rahkonen-
>>
>>
>>
>> *Lähettäjä:* gdal-dev <gdal-dev-bounces at lists.osgeo.org> *Puolesta *Stijn
>> Tallir
>> *Lähetetty:* keskiviikko 16. elokuuta 2023 10.29
>> *Vastaanottaja:* gdal-dev at lists.osgeo.org
>> *Aihe:* [gdal-dev] tps - gdalwarp vs ogr2ogr
>>
>>
>>
>> Hi,
>>
>>
>>
>> According to the documentation gdal and ogr use the same algorithm for
>> the tps-transformation but I don't seem to get the same results using the
>> same set of gcp's for images and vectors.
>>
>>
>>
>> I have images that are unreferenced and vector data digitised on these
>> images (in pixel coordinates).
>>
>>
>>
>> The images are then georeferenced with +100 gcp's and warped with
>> gdalwarp using the "tps" option.
>>
>>
>>
>> When I use the same gcp's (with adjusted y-origin to lower left corner)
>> to georeference the vector data with ogr2ogr and the "tps" option I get
>> different results. The vector-result is similar to the image-result but
>> never exactly the same and differences can be substantial.
>>
>>
>>
>> Any thoughts?
>>
>>
>>
>> Stijn
>>
>>
>>
>>
>> --
>>
>> Stijn Tallir - StrICT BV
>>
>>
>>
>> Wijnveld 8
>>
>> 9112 Sinaai-Waas
>>
>>
>>
>> GSM: 0486 750220
>>
>>
>>
>> E-mail: Info at strict.be
>>
>> Web: www.strict.be
>>
>>
>>
>> BTW: BE 0567.559.668
>>
>>
>>
>>
>>
>>
>> --
>>
>> Stijn Tallir - StrICT BV
>>
>>
>>
>> Wijnveld 8
>>
>> 9112 Sinaai-Waas
>>
>>
>>
>> GSM: 0486 750220
>>
>>
>>
>> E-mail: Info at strict.be
>>
>> Web: www.strict.be
>>
>>
>>
>> BTW: BE 0567.559.668
>>
>>
>>
>>
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