[QGIS-Developer] GSoC 2021 QGIS On-the-fly Raster Calculator proposal draft review and feedback

[Julien Cabieces]

Hi,

Nice proposal Francesco!

I already worked on a projet where such a feature could have been of great
values, I will follow your work with interest.

I like also the Alister proposal, and already thought about a "virtual
raster" connected to a raster processing that you run on-the-fly
according to the map extent. This way, we could run process on raster
subpart, and update it while the user move in map. It would be
interesting for raster stored on a server, like COG for instance.

Don't know if it's technically feasible though.

Regards,
Julien


>>
>> Hi,
> This functionality would be great, but as a user, I can't help thinking the
> proposal is to implement it in the wrong way.
>
> If implemented as a renderer, as described, you could conceivably use an
> expression that uses other layers but not the layer you are supposedly
> rendering.  What is displayed would not correspond in any way to the actual
> layer... Bizarre.
>
> Would it not be possible to instead implement a "virtual raster"
> *provider*?  Add a checkbox in the raster calculator labelled "create as
> virtual raster".  Create a new layer that can be styled using the existing
> renderers and behaves in every way like a non-virtual layer - e.g. the
> right values would be shown using the identify tool and the "value tool"
> plugin, and you could use the layer as an input for other processing tools.
>
> Regards, and best wishes with the proposal,
> Alister
>
> Date: Mon, 12 Apr 2021 12:20:53 +0000
>> From: Francesco Bursi <francesco.bursi at hotmail.it>
>> To: qgis-developer <qgis-developer at lists.osgeo.org>
>> Subject: [QGIS-Developer] GSoC 2021 QGIS On-the-fly Raster Calculator
>>         proposal draft review and feedback
>> Message-ID:
>>         <
>> VI1P190MB038187BB910511B3B6B8B44280709 at VI1P190MB0381.EURP190.PROD.OUTLOOK.COM
>> >
>>
>> Content-Type: text/plain; charset="windows-1252"
>>
>> Hello QGIS Dev,
>>
>>
>> I?m Francesco Bursi, an M.Sc. civil engineer from Italy currently enrolled
>> in a Master of Advanced Studies (Level 8 EQF) in giscience and
>> geoinformatics at the University of Padua.
>>
>> I?m really interested in the QGIS (possible) new rendering feature that
>> involves raster calculator capabilities, I've already discussed the project
>> with mentors Martin Tobias and Peter Petrik and possible co-mentor Roberto
>> Marzocchi,  they gave me a lot of feedback and advice for the project.
>> I would like to share my proposal with you before the final submission.
>> Don't hesitate to give me feedback and ask me question/clarification or
>> point me out what's missing.
>>
>>
>> proposal 2021<
>> https://docs.google.com/document/d/1u8L_L1IJjGCZ3d8Vq8duxHbsHZeyzwqOe3tXa1JcKbs/edit?usp=sharing
>> >
>>
>>
>> I'm open to advice, remarks and criticism in order to improve.
>>
>> I am looking forward to a feedback, thank you for your time.
>>
>>
>> Best regards,
>>
>> Francesco Bursi
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