[Qgis-user] Symbolizing a discrete or a boolean raster (Stéphane Henriod)
Richard McDonnell
richard.mcdonnell at opw.ie
Tue Jan 10 09:14:41 PST 2017
Harrissou,
Not sure if this is a solution, or if anyone has already given you this
answer, but.... if you know a classified raster has *50* values, which
you wish to style individually, you could try setting*:
*
* *Colour Interpolation* to *Linear*
* *Mode *to*Equal Interval*
* *Classes *to*51 *(one more than the Max)
I have only just tested this on a raster with 4 values and its worked
for me!
Hope this helps!
Regards,
Richard.
On 10/01/2017 09:49, DelazJ wrote:
> Hi Stéphane,
>
> 2017-01-10 4:02 GMT+01:00 Stéphane Henriod <s at henriod.info
> <mailto:s at henriod.info>>:
>
> Hi Chris
>
> this is very nice! I indeed didn't know this trick and will
> certainly use it again in the future!
>
> However... :-)
>
> I am currently teaching QGIS to beginners and this for sure is not
> an appropriate method for them (especially in the case you have to
> generate the symbology file through a script)!
>
> Since the user can style continuous rasters with some
> "button-clicking", I believe the same option should be available
> for discrete rasters as well.
>
> I am thus wondering if anyone else than me sees it as a priority
> for QGIS? If yes, how to motivate the developers to take it for
> the next release and / or how much would such a development cost?
> (I unfortunately don't have the competences to do it myself)
>
> There have been some work done in the raster properties dialog in the
> upcoming 3.0. I don't know if your concern was covered though.
> If you want, you can move the question to the developer's list
> <http://qgis.org/en/site/getinvolved/mailinglists.html#qgis-developers-list>
> and discuss whether/how this can be implemented (and its requirements).
>
> Regards,
> Harrissou
>
> Thanks again and cheers!
>
> Stéphane
>
>
> Le mardi 10 janvier 2017, Chris House <housec01 at gmail.com
> <mailto:housec01 at gmail.com>> a écrit :
>
> Hi Stéphane,
>
> I don't know if this is what you are looking for or not but I
> have a method of classifying rasters by color based on a set
> (standard) colors. I created a spreadsheet that has several
> required columns, value, red, green, blue...and you can have
> an optional field for a display value. So say value 1 is
> water you can use that last column to name that value so that
> in the QGIS layer tree and in legend it says Water instead of
> value 1.
>
> save the spreadsheet as a csv and change the extension to .txt
> instead of .csv.
>
> I then go into the symbology section of the raster choose
> singleband pseudocolor. Use the folder to browse to your text
> file and click add. There is a format for this text file. It
> is below. If you need me to email it I will do that in direct
> email.
>
> # QGIS Generated Color Map Export File
> INTERPOLATION:EXACT
> -9999,0,0,0,255,NoData
> 0,176,176,176,255,Non-Forested
> 15,234,255,191,255,10 <= CC < 20
> 25,187,230,149,255,20 <= CC < 30
> 35,140,201,109,255,30 <= CC < 40
> 45,98,176,74,255,40 <= CC < 50
> 55,59,153,43,255,50 <= CC < 60
> 65,0,128,0,255,60 <= CC < 70
> 75,15,92,11,255,70 <= CC < 80
> 85,17,61,12,255,80 <= CC < 90
> 95,16,36,12,255,90 <= CC <= 100
>
> In my example if I don't assign a value it gets ignored by
> QGIS. If you are wondering how to assign unique colors to say
> 200 unique values...just script it. I have done this and as
> long as you have the number of unique values you want and to
> make them unique in the script it works.
>
> I hope this helps. I know it isn't a "button" but to be
> honest I like this better. If you already knew this...well
> then maybe it will help someone out in the future.
>
> --Chris
>
> On Mon, Jan 9, 2017 at 3:00 PM,
> <qgis-user-request at lists.osgeo.org> wrote:
>
> Send Qgis-user mailing list submissions to
> qgis-user at lists.osgeo.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://lists.osgeo.org/mailman/listinfo/qgis-user
> <http://lists.osgeo.org/mailman/listinfo/qgis-user>
> or, via email, send a message with subject or body 'help' to
> qgis-user-request at lists.osgeo.org
>
> You can reach the person managing the list at
> qgis-user-owner at lists.osgeo.org
>
> When replying, please edit your Subject line so it is more
> specific
> than "Re: Contents of Qgis-user digest..."
>
>
> Today's Topics:
>
> 1. Re: Symbolizing a discrete or a boolean raster
> (Stéphane Henriod)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 9 Jan 2017 23:07:36 +0600
> From: Stéphane Henriod <s at henriod.info>
> To: Enrico Fiore <enricofiore at libero.it>
> Cc: qgis-user <qgis-user at lists.osgeo.org>
> Subject: Re: [Qgis-user] Symbolizing a discrete or a
> boolean raster
> Message-ID:
>
> <CAK6pVBXURm_e7dRP+8SP9amPUUX0+Cn3GVxLPNjOHhno85o2rA at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hi
>
> thanks for following up!
>
> It actually does part of the job!
>
> Using *Color interpretation: Exact*, I can indeed input
> the exact values I
> want to display (1,5 and 10) and all other pixels are hidden.
>
> HOWEVER,
>
> this still feels like a workaround:
>
> - In the case of a discrete raster with many (> 50)
> unique values, I do
> not want to input all of them manually
> - In some cases, I do not know in advance all the
> unique values of my
> raster
> - If I click on *Classify*, QGIS will choose X values
> (based on the
> number of classes and the classification method
> (continuous or equal
> interval)), which no longer match the "exact" values of
> my raster. It
> doesn't really make sense to classify a discrete rendering
>
> So I would say, we still need a render type "discrete
> raster" which offers
> the function to "retrieve all unique values" (and
> automatically apply a
> discrete color ramp)
>
> Attached a (fake) test dataset.
>
> Thanks and cheers
>
> Stéphane
>
>
> Le lundi 9 janvier 2017, Enrico Fiore
> <enricofiore at libero.it> a écrit :
>
> > Hi,
> > Sorry I can't do test, but if you use exact in color
> interpolation
> > parameter?
> >
> > Cheers
> >
> > Enrico
>
>
> Le lundi 9 janvier 2017, Stéphane Henriod <s at henriod.info>
> a écrit :
>
> > Hi
> >
> > unfortunately this is doing quite something different!
> >
> > If I have a raster with 10 Landcover classes
> (1,2,3,4,5,6,7,8,9,10) and I
> > want to display only 1,5 and 10, using *Discrete *(1:
> red, 5: yellow, 10:
> > blue) the following will happen:
> >
> > All pixels between 1 and 4 will be red
> > All pixels between 5 and 9 will be yellow
> > All pixels with 10 will be blue
> >
> > In this sense, the pixels are indeed not interpolated,
> but this still is
> > not the behavior I am expecting when styling discrete
> rasters.
> >
> > A "style discrete raster" function should offer the
> following:
> >
> > - Automatically recover all unique values from the raster
> > - Only display the pixels to which the user has
> explicitly assigned a
> > color
> >
> > But thanks for your hint, this can be helpful in other
> cases!
> >
> > Cheers
> >
> > Stéphane
> >
> >
> > Le lundi 9 janvier 2017, Enrico Fiore <enricofiore at libero.it
> > <javascript:_e(%7B%7D,'cvml','enricofiore at libero.it');>>
> a écrit :
> >
> >> Hi,
> >> I think that the solution is in the QGIS documentation,
> that you can read
> >> here:
> http://docs.qgis.org/2.14/en/docs/user_manual/working_with_r
> <http://docs.qgis.org/2.14/en/docs/user_manual/working_with_r>
> >> aster/raster_properties.html#band-rendering
> >> you have to use *Singleband pseudocolor *and set color
> interpolation to
> >> Discrete.
> >>
> >> Enrico
> >>
> >>
> >> ----Messaggio originale----
> >> Da: "Stéphane Henriod" <s at henriod.info>
> >> Data: 09/01/2017 6.30
> >> A: "qgis-user"<qgis-user at lists.osgeo.org>
> >> Ogg: [Qgis-user] Symbolizing a discrete or a boolean raster
> >>
> >> Dear all
> >>
> >> As much as I love QGIS and use it in my everyday life,
> there is one
> >> feature that I find particularly annoying: the styling
> of discrete rasters.
> >>
> >> Basically, if I have a raster layer consisting of
> discrete landcover
> >> values (1: water, 2: forest, 3: built-up), it seems
> that there is no easy
> >> way to style it. QGIS will assume that the data is
> continuous and basically
> >> interpolate the color between each value, which leads
> to the following
> >> issues:
> >>
> >> Let's say I want to display only water and built-up
> (values 1 and 3),
> >> water in blue and built-up in grey. QGIS will still
> display the forests,
> >> using a color somewhere "between" blue and grey. My
> only left option is to
> >> process the raster to actually replace all the 2 with
> NoData, which is
> >> highly unpractical...
> >>
> >> Same if I have a boolean raster (only 0 and 1 values).
> QGIS will by
> >> default make a color ramp from 0 to 0.9999.
> >>
> >> Also, the whole rather feels like a work-around for a
> missing feature.
> >>
> >> I dream of a feature similar to this one from ArcGIS:
> >> http://resources.arcgis.com/en/help/main/10.1/index
> <http://resources.arcgis.com/en/help/main/10.1/index>.
> >>
> html#/representing_unique_categories_such_as_land_use/009t00000074000000/
> >> where all unique values are styled independently and
> where I can easily
> >> skip the values I don't want to see on my map.
> >>
> >> I asked a question here:
> >>
> http://gis.stackexchange.com/questions/194116/qgis-style-a-d
> <http://gis.stackexchange.com/questions/194116/qgis-style-a-d>
> >> iscrete-raster
> >>
> >> and opened a ticket here:
> >> http://hub.qgis.org/issues/14845
> <http://hub.qgis.org/issues/14845>
> >>
> >> But none has gotten lots of attention yet... Am I the
> only one to be
> >> annoyed by this? If no, please raise your hand and
> let's try to get some
> >> momentum and see how to push this feature forward!
> >>
> >> Thanks a lot in advance!
> >>
> >> Cheers
> >>
> >> Stéphane
> >>
> >>
> >
>
> --
> Stéphane Henriod
> CIM-Expert for GIS and Green Economy Statistics
>
> Национальный статистический комитет Кыргызской Республики
> Кыргыз Республикасынын Улуттук статистика комитети
> National Statistical Committee of the Kyrgyz Republic
>
> 374 Фрунзе ул. / Frunze str.
> 720033 Бишкек / Bishkek
>
> T +996 778 46 99 02 (KG)
> T +49 176 280 11 050 <tel:+49%20176%2028011050> (DE)
> E s at henriod.info
> W http://www.stat.kg
> W3W: nightfall.into.bucket
> <https://map.what3words.com/nightfall.into.bucket
> <https://map.what3words.com/nightfall.into.bucket>> //
> запас.союз.дружный
> <https://map.what3words.com/запас.союз.дружный>
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL:
> <http://lists.osgeo.org/pipermail/qgis-user/attachments/20170109/985fd14c/attachment-0001.html
> <http://lists.osgeo.org/pipermail/qgis-user/attachments/20170109/985fd14c/attachment-0001.html>>
> -------------- next part --------------
> A non-text attachment was scrubbed...
> Name: landcover.zip
> Type: application/zip
> Size: 2151 bytes
> Desc: not available
> URL:
> <http://lists.osgeo.org/pipermail/qgis-user/attachments/20170109/985fd14c/attachment-0001.zip
> <http://lists.osgeo.org/pipermail/qgis-user/attachments/20170109/985fd14c/attachment-0001.zip>>
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> Qgis-user mailing list
> Qgis-user at lists.osgeo.org
> List info:
> http://lists.osgeo.org/mailman/listinfo/qgis-user
> <http://lists.osgeo.org/mailman/listinfo/qgis-user>
> Unsubscribe:
> http://lists.osgeo.org/mailman/listinfo/qgis-user
> <http://lists.osgeo.org/mailman/listinfo/qgis-user>
>
> ------------------------------
>
> End of Qgis-user Digest, Vol 131, Issue 13
> ******************************************
>
>
>
>
> --
> Stéphane Henriod
> CIM-Expert for GIS and Green Economy Statistics
>
> Национальный статистический комитет Кыргызской Республики
> Кыргыз Республикасынын Улуттук статистика комитети
> National Statistical Committee of the Kyrgyz Republic
>
> 374 Фрунзе ул. / Frunze str.
> 720033 Бишкек / Bishkek
>
> T +996 778 46 99 02 (KG)
> T +49 176 280 11 050 <tel:+49%20176%2028011050> (DE)
> E s at henriod.info <mailto:s at henriod.info>
> W http://www.stat.kg
> W3W: nightfall.into.bucket
> <https://map.what3words.com/nightfall.into.bucket> //
> запас.союз.дружный
> <https://map.what3words.com/%D0%B7%D0%B0%D0%BF%D0%B0%D1%81.%D1%81%D0%BE%D1%8E%D0%B7.%D0%B4%D1%80%D1%83%D0%B6%D0%BD%D1%8B%D0%B9>
>
>
> _______________________________________________
> Qgis-user mailing list
> Qgis-user at lists.osgeo.org <mailto:Qgis-user at lists.osgeo.org>
> List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
> <http://lists.osgeo.org/mailman/listinfo/qgis-user>
> Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
> <http://lists.osgeo.org/mailman/listinfo/qgis-user>
>
>
>
>
> _______________________________________________
> Qgis-user mailing list
> Qgis-user at lists.osgeo.org
> List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
--
*_Richard McDonnell_*
*GIS Specialist PgD GIS AssocSCSI*
*OPW FRM Data Management*
*52 Stephens Green, Dublin 2.*
TEL: 01 6476543
OPW - Ag féachaint don am atá le teacht - Ag caomhnú ón am atá thart
OPW - Looking to the future - Caring for the past
***********************************************************
Email Disclaimer: http://www.opw.ie/en/disclaimer/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-user/attachments/20170110/5003ca3c/attachment.html>
More information about the Qgis-user
mailing list