[gdal-dev] mosaicking files with partial overlap and binary mask

[Patrick Young]

I do not!

If you want to try it out without building latest yourself and can use
docker, you can snag one of the latest containers here and see if it works
for you:

https://hub.docker.com/r/osgeo/gdal/tags?page=1&ordering=last_updated

Best,
Patrick

On Thu, Jan 28, 2021 at 2:12 AM Daniele Romagnoli <
daniele.romagnoli at geo-solutions.it> wrote:

> Hi Patrick,
> nice!
> Thanks for the feedback.
>
> Do you have any info about eventual backports to previous versions?
>
> Regards,
> Daniele
>
> On Thu, Jan 28, 2021 at 12:02 AM Patrick Young <
> patrick.mckendree.young at gmail.com> wrote:
>
>> Hi Daniele,
>>
>> Even added this functionality to VRTs just recently, see
>>
>> https://lists.osgeo.org/pipermail/gdal-dev/2020-December/053178.html
>>
>> I think it is slated for GDAL 3.3 but you could always build the bleeding
>> edge.
>>
>> Patrick
>>
>> On Wed, Jan 27, 2021 at 3:50 AM Daniele Romagnoli <
>> daniele.romagnoli at geo-solutions.it> wrote:
>>
>>> Hi list,
>>> I have some TIFF datasets with partially overlapping edges and embedded
>>> binary masks to keep into account which parts along the edges should be
>>> masked out.
>>> When showing all the images on QGIS it looks good since the binary mask
>>> do its job by making the "black/white" overlapping edge masked out.
>>>
>>> Now I need to create a single TIF from all of these images.
>>> I have tried with gdalbuildvrt but it doesn't produce good result.
>>> Checking the doc I saw this:
>>>
>>>
>>> *If there is some amount of spatial overlapping between files [...]
>>> currently, alpha channel is not taken into account to do alpha compositing
>>> (so a source with alpha=0 appearing on top of another source will override
>>> is content). This might be changed in later versions.  *
>>>
>>> So I think it's expected and I have switched to gdal_merge.py.
>>> It works better since it does alpha compositing but it looks like the
>>> result doesn't preserve the binary mask which I still need since I have M
>>> groups of N files which I need to process in 2 passes:
>>> - the inner group of N files get merged using the binary mask to a
>>> bigger file.
>>> - all the M bigger files get mosaicked again to a single huge file.
>>>
>>> I will spend some more time in testing different attempts.
>>> In the meantime, do you have any suggestion or past experience on how to
>>> deal with that?
>>> Side note: I have vague memory of gdal_merge being somehow memory
>>> bounded, throwing memory allocation errors when trying to compose big
>>> images. This is why in the past I was using gdalbuildvrt to do composition
>>> (without overlapping).
>>>
>>> Thanks in advance.
>>> Regards,
>>> Daniele
>>>
>>>
>>>
>>>
>>> --
>>> Regards,
>>> Daniele Romagnoli
>>> ==
>>> GeoServer Professional Services from the experts! Visit
>>> http://goo.gl/it488V for more information.
>>> ==
>>>
>>> Ing. Daniele Romagnoli
>>> Senior Software Engineer
>>>
>>> GeoSolutions S.A.S.
>>> Via di Montramito 3/A
>>> 55054  Massarosa (LU)
>>> Italy
>>> phone: +39 0584 962313
>>> fax:      +39 0584 1660272
>>>
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>>
>
> --
> Regards,
> Daniele Romagnoli
> ==
> GeoServer Professional Services from the experts! Visit
> http://goo.gl/it488V for more information.
> ==
>
> Ing. Daniele Romagnoli
> Senior Software Engineer
>
> GeoSolutions S.A.S.
> Via di Montramito 3/A
> 55054  Massarosa (LU)
> Italy
> phone: +39 0584 962313
> fax:      +39 0584 1660272
>
> http://www.geo-solutions.it
> http://twitter.com/geosolutions_it
>
> -------------------------------------------------------
>
> Con riferimento alla normativa sul trattamento dei dati personali (Reg. UE
> 2016/679 - Regolamento generale sulla protezione dei dati “GDPR”), si
> precisa che ogni circostanza inerente alla presente email (il suo
> contenuto, gli eventuali allegati, etc.) è un dato la cui conoscenza è
> riservata al/i solo/i destinatario/i indicati dallo scrivente. Se il
> messaggio Le è giunto per errore, è tenuta/o a cancellarlo, ogni altra
> operazione è illecita. Le sarei comunque grato se potesse darmene notizia.
>
> This email is intended only for the person or entity to which it is
> addressed and may contain information that is privileged, confidential or
> otherwise protected from disclosure. We remind that - as provided by
> European Regulation 2016/679 “GDPR” - copying, dissemination or use of this
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