[QGIS-Developer] Projects without a CRS

[Andreas Neumann]

Hi, 


I am wondering about projects without a CRS. While a new project now
always comes with a CRS (depending on the global CRS settings), the user
can still explicitly disable a definition of a CRS in Menu "Project" -->
"Properties" --> "CRS" 

I have the following questions about projects without a CRS: 

- what are the restrictions/limitations of projects without a CRS? 


- assuming that a layer has a CRS (e.g. a Postgis layer that has a CRS)
is loaded into a project that explictly has no CRS set - does QGIS still
know the CRS of the Postgis layer or would it treat it as a CRS-less
layer? 


- does it still make sense to support projects without a CRS? If yes,
what are the use cases? 


- will it still be possible to have projects without a CRS or will this
one day be deprecated 


I personally do understand that it is not a good idea to have projects
with no CRS defined, but I am trying to understand and convince my
colleagues at my workplace that projects without a CRS are an absolute
nogo. But maybe I am wrong and it still makes sense to support projects
without a CRS. 


One use case I could think of for projects without a CRS, is using QGIS
for something that is planar, but not geographic in nature, e.g. a
non-GIS topic, such as examining an image (let's say the enlarged view
of an electron microscope of some small thing) where the user might want
to "map" certain characteristics of the image, but the object itself is
"mobile" (can move around) and is not fixed to a fixed position of the
earth. 

What are your thoughts about projects without a CRS? 

Greetings, 


Andreas___
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Re: [QGIS-Developer] QGIS 3.8 Transformations dialog

[Nyall Dawson]

On Fri, 28 Jun 2019 at 17:29, Nyall Dawson  wrote:
>
> On Fri, 28 Jun 2019 at 17:11, Richard Duivenvoorde  
> wrote:
> >
> > On 28/06/2019 01.28, Nyall Dawson wrote:
> > >> That one shows 'just' 2 options (added to the qgis.nl post)
> > >> IF the green line is just the first one, but we are not sure if it is
> > >> the right one... should we make it green anyway?
> >
> > > Ah, on proj 6 builds, we ARE sure that the first/green one is the most
> > > recommended one :) That's because proj gives us an ordered list of
> > > possible operations in order of preference (calculated using all
> > > proj's internal smarts and knowledge about the accuracy of different
> > > transform operations).
> >
> > Mmm, then my last question, after this I'll move to proj ;-)
> >
> > See:
> >
> > http://www.qgis.nl/media/2019/06/Screenshot-20190627104509-716x467.png
> >
> > This is QGIS with proj6: As you see there are 2 options. The first one
> > being green 'numbered' (3). But the bottom one having a higher number
> > between brackets having a (4) between brackets?
> >
> > Now /me wondering what these numbers are: because given your answer
> > above, the green one being 'THE one' :-) I wonder what this other
> > numbers are (I was wondering ordered by date/relevance or so)??
>
> These are how proj identifies the coordinate operation -- I'm not
> entirely sure what they represent, but I assume they are just indexes.

Just for followers of this thread - conversation moved to the proj
mailing list, and looks like it will result in improved descriptive
strings coming as a result...
Nyall
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Re: [QGIS-Developer] Sunrise, Sunset, Lunar Calculations

[Nyall Dawson]

On Fri, 28 Jun 2019 at 23:13, C Hamilton  wrote:
>
> Thank you for all the comments. To summarize.
>
> 1. Having this capability would be useful.
> 2. Take a look at pvlib.
> 3. Add it to expression functions and possibly add it as a core C++ function.
> 4. Take a look at GRASS r.sun and related commands.
> 5. Take a look at the astral library.
> 6. Take a look at GEarthView
>
> My philosophy is that QGIS is a professional GIS application and as such its 
> algorithms used need to be the most accurate that are available. The Sun and 
> Lunar algorithms are not trivial and I would want to use an existing library. 
> I know there are some simplified approximation algorithms that you find used 
> on the web particularly in JavaScript mapping applications. I would prefer 
> the more accurate algorithms, but will be limited somewhat with what I can 
> easily include.
>
> If this capability were to be added as core C functions, then I think you 
> would need to link it to one of the astronomical libraries. I think all of 
> the python libraries are probably in part derived from the C libraries. Is 
> adding an astronomical library to QGIS of interest? I don't think we should 
> use the simplified algorithms. I have not looked into C libraries, but I know 
> that the author of Skyfield (formerly PyEphem which is now deprecated) based 
> his code on the US Naval Observatory NOVAS library. I can see that having 
> astronomical calculations in QGIS would be beneficial to some and could even 
> open it up to other uses, but I don't know how much you would be interested 
> in making these core functions, but lets start the discussion as it might 
> affect my approach.
>

I think (given Martin's desire to add this capability to the 3d
engine) that yes, there's a valid use case for this. And I'd MUCH
prefer to have this out of the box vs a 3rd party plugin. I'd suggest
doing a review of the available libraries, in order to determine which
are possible candidates wrt to features and license, and also
determine how actively maintained upstream is, and then we can make an
informed decision from there...

Nyall
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Re: [QGIS-Developer] GSoC QGIS 3D Improvement: Week 4 Report

[Ismail Sunni]

Hi Tim,

Sorry, I missed this email from you.

Thanks for the update Sunni! Do measurements happen in 3d too? For example
> if you measure to the top of a building do you get a different measurement
> compared to the base?


Yes, the measurements happen in 3D. You can measure the building height now
:)


> Maybe you could show the Z elevation change at each measurement row and
> the total elevation change  in the total box?


Hmm, that's a good idea. I will keep it on my list, and I will try to
implement it after the other 2 features finished. Thanks!

Hope you are feeling better now!


Thanks, I am feeling better indeed now :)

Best regards


On Sun, Jun 23, 2019 at 8:34 PM Tim Sutton  wrote:

> Thanks for the update Sunni! Do measurements happen in 3d too? For example
> if you measure to the top of a building do you get a different measurement
> compared to the base? Maybe you could show the Z elevation change at each
> measurement row and the total elevation change  in the total box?
>
> Hope you are feeling better now!
>
> Regards
>
> Tim
>
> On 23 Jun 2019, at 15:29, Ismail Sunni  wrote:
>
> Dear QGIS developers,
>
> Here is my 3rd-week report for my GSoC Project. You can read this report
> better with image and GIF in the weekly report wiki [6]. You can also check
> the project wiki page [3]. Comments and suggestions are welcome :)
>
> GSoC QGIS 3D Improvement Week 4 Report
>
> *Period*: 17 June 2019 - 23 June 2019
>
> *Report*
> 1. What did I complete this week?
>- Replicate UI from 2D measurement tool to the 3D measurement tool
> dialog.
>  Almost all functionalities are replicated, except:
>  - Show help (the behavior is added, but since there is no chapter for
> it currently. It's disabled for now)
>  - Configuration (already started working on it, but time is quite
> limited last week since I feel a little bit unwell last week)
>
>  List of implemented behaviors can be found in [4]. You can see it on
> a GIF [5].
>  ![3D Measurement Tool with Dialog](
> https://user-images.githubusercontent.com/1421861/59976840-2a78c100-95ca-11e9-9e32-16b6c34b4ce9.gif
> )
>- Adding map tool for camera control in 3D view (similar to the Pan
> tool in 2D view) to make it more consistent and easier to see what's the
> active tool.
>- Change the cursor for 3D identify tool for consistency with 2D one.
>- Adding missing `QgsDistanceArea::MeasureLine3D` for `QgsPoint`, unit
> test is added.
>- Trying to fix the rendering issue, but still no luck.
> 2. What am I going to achieve for next week?
>- Finish the configuration
>- Try again with the rendering issue
>- Wrap up PR if the all is finished (currently a draft)
>- Some testing
>- Start working on the 3rd feature, point as a billboard.
> 3. Is there any blocking issue?
>- Yes, the line is rendered but the color is random and rendered as 2D.
> The line will be gone if I hide/show another line [2].
>  ![Rendering Problem](
> https://user-images.githubusercontent.com/1421861/59567331-c22b5c00-906c-11e9-808f-0a7e93e8f54a.png
> )
> 4. Code
>- Branch in my repo [1]
> 5. Misc
>- N/A
>
> *References*
> - [1] https://github.com/ismailsunni/QGIS/tree/measurement-tool
> - [2] https://github.com/ismailsunni/QGIS/issues/2#issuecomment-502470762
> - [3] Project Wiki:
> https://github.com/ismailsunni/QGIS/wiki/GSoC-2019---QGIS-3D-Improvement
> - [4] https://github.com/ismailsunni/QGIS/issues/2#issuecomment-504750318
> - [5]
> https://user-images.githubusercontent.com/1421861/59976840-2a78c100-95ca-11e9-9e32-16b6c34b4ce9.gif
> - [6] https://github.com/ismailsunni/QGIS/wiki/Week-4-Report
>
> Best regards
>
> --
> Ismail Sunni
> ismailsunni.wordpress.com
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>
> —
>
>
>
>
>
>
>
>
> *Tim Sutton*
>
> *Co-founder:* Kartoza
> *Ex Project chair:* QGIS.org
>
> Visit http://kartoza.com to find out about open source:
>
> Desktop GIS programming services
> Geospatial web development
> GIS Training
> Consulting Services
>
> *Skype*: timlinux
> *IRC:* timlinux on #qgis at freenode.net
>
> I'd love to connect. Here's my calendar link
>  to make finding time easy.
>
>

-- 
Ismail Sunni
ismailsunni.wordpress.com
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[QGIS-Developer] GSoC QGIS 3D Improvement: Week 5 Report

[Ismail Sunni]

Dear QGIS developers,

Here is my 5th-week report for my GSoC Project. You can read this report
better with image and GIF in the weekly report wiki [4]. You can also check
the project wiki page [3]. Comments and suggestions are welcome :)

GSoC QGIS 3D Improvement Week 5 Report

*Period*: 24 June 2019 - 30 June 2019

*Report*
1. What did I complete this week?
   - Addressing PR's review (quite a lot, especially the dialog's behavior
and not using QgsDistanceArea).
   - Adding measurement configuration
   - Filling evaluation phase 1
2. What am I going to achieve for next week?
   - Start working on the 3rd feature, point as a billboard.
   - Addressing measurement tool's PR review (if any)
3. Is there any blocking issue?
   - The previous rendering issue is solved by Martin.
4. Code
   - Branch in my repo [1] and the PR [2]
5. Misc
   - N/A

References
- [1] https://github.com/ismailsunni/QGIS/tree/measurement-tool
- [2] https://github.com/qgis/QGIS/pull/30299
- [3] Project Wiki:
https://github.com/ismailsunni/QGIS/wiki/GSoC-2019---QGIS-3D-Improvement
- [4] https://github.com/ismailsunni/QGIS/wiki/Week-5-Report

Best regards

-- 
Ismail Sunni
ismailsunni.wordpress.com
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Re: [QGIS-Developer] Sunrise, Sunset, Lunar Calculations

[Rainer Hurling]

Am 27.06.19 um 21:14 schrieb C Hamilton:
> How much interested would there be for a plugin to display sunrise and
> sunset information for a particular location on the earth's surface. Is
> anyone already working on this? There doesn't seem to be a capability
> for this, but perhaps I have missed it. Are there other astronomical
> calculations that would be worth while in QGIS? (Moon asimuth/position,
> phase)
> 
> I a trying to get a sense of interest and also make sure I am not
> duplicating a capability someone is already working on.
> 
> Thanks,
> 
> Calvin
> 

SAGA GIS also has a tool for it since 2015:

  Climate -> Tools -> Sunrise and Sunset

It is raster data based: "This tool calculates the time of sunrise and
sunset and the resulting day length for each cell of the target grid.
The target grid needs to provide information about its coordinate system."

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