I've converted road polylines to polygons before by buffering. You may have to do different road grades/widths in several stages.
On 31 July 2015 05:39:15 BST, [email protected] wrote: >Send Qgis-user mailing list submissions to > [email protected] > >To subscribe or unsubscribe via the World Wide Web, visit > http://lists.osgeo.org/mailman/listinfo/qgis-user >or, via email, send a message with subject or body 'help' to > [email protected] > >You can reach the person managing the list at > [email protected] > >When replying, please edit your Subject line so it is more specific >than "Re: Contents of Qgis-user digest..." > > >------------------------------------------------------------------------ > >Today's Topics: > > 1. Layer question (Shane) > 2. Re: Layer question (Tom Lennon) > 3. Re: Layer question (Bernd Vogelgesang) > 4. Re: Layer question (Nicolas Cadieux) > 5. Re: How to convert raster routes into vector format? > (Nick Papadonis) > 6. Raster Calculator Expression to determine color (Nick Papadonis) > 7. Re: Raster Calculator Expression to determine color (Nyall Dawson) > 8. Re: Raster Calculator Expression to determine color > (Nick Papadonis) > 9. Re: Raster Calculator Expression to determine color > (Nick Papadonis) > 10. Re: Raster Calculator bug? (Nick Papadonis) > > >------------------------------------------------------------------------ > >From: Shane <[email protected]> >To: [email protected] >Sent: Thu Jul 30 20:05:09 BST 2015 >Subject: [Qgis-user] Layer question > > Hi group, > > I have a layer with roads which are lines having a style of gray >with thin black outlines on either side. Another layer (parking lots) >has polygons having the same color as the roads but not outlined. The >parking lot layer is above the road layer in rendering order. So road >outlines are hidden by the parking lot layer when a parking lot >intersects a road. > > Here's the trouble - having parking lots with no outline, but roads >with outlines looks odd. Is there some way to have the outlines of >both >road and parking lot layers removed from rendering when these two >features cross? > > One method I've considered is to draw the roads and parking lots as >polygons in the same layer? It would make drawing the roads >non-trivial, but the problem with outlines would be eliminated. > > Shane > > > > >------------------------------------------------------------------------ > >From: Tom Lennon <[email protected]> >To: Shane <[email protected]> >Cc: qgis-user <[email protected]> >Sent: Thu Jul 30 22:11:17 BST 2015 >Subject: Re: [Qgis-user] Layer question > >Hi Shane: >Have you tried moving the parking lot layer to below the road layer? >That way roads over parking lots would always show. > >Tom > >On Thu, Jul 30, 2015 at 3:05 PM, Shane <[email protected]> wrote: > >> Hi group, >> >> I have a layer with roads which are lines having a style of gray >with >> thin black outlines on either side. Another layer (parking lots) has >> polygons having the same color as the roads but not outlined. The >parking >> lot layer is above the road layer in rendering order. So road >outlines are >> hidden by the parking lot layer when a parking lot intersects a road. >> >> Here's the trouble - having parking lots with no outline, but >roads >> with outlines looks odd. Is there some way to have the outlines of >both >> road and parking lot layers removed from rendering when these two >features >> cross? >> >> One method I've considered is to draw the roads and parking lots >as >> polygons in the same layer? It would make drawing the roads >non-trivial, >> but the problem with outlines would be eliminated. >> >> Shane >> >> _______________________________________________ >> Qgis-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-user >> > > > >-- >[email protected] > > >------------------------------------------------------------------------ > >From: Bernd Vogelgesang <[email protected]> >To: [email protected] >Sent: Thu Jul 30 22:50:36 BST 2015 >Subject: Re: [Qgis-user] Layer question > >Hi Shane, >I think without a screenshot, we have no chance to really get an idea >what >it's all about. >Best to use a service like http://imgur.com/ and post the link cause >the >list will bounce too heavy attachments. > >Bernd > > > >Am 30.07.2015, 23:11 Uhr, schrieb Tom Lennon <[email protected]>: > >> Hi Shane: >> Have you tried moving the parking lot layer to below the road layer? >> That way roads over parking lots would always show. >> >> Tom >> >> On Thu, Jul 30, 2015 at 3:05 PM, Shane <[email protected]> wrote: >>> Hi group, >>> >>> I have a layer with roads which are lines having a style of gray >with >>> thin black outlines on either side. Another layer >>(parking lots) >has >>> polygons having the same color as the roads but not outlined. The >>> parking lot layer is above the road layer in >>rendering order. So > >>> road outlines are hidden by the parking lot layer when a parking lot > >>> intersects a road. >>> >>> Here's the trouble - having parking lots with no outline, but >roads >>> with outlines looks odd. Is there some way to have the >>outlines >of >>> both road and parking lot layers removed from rendering when these >two >>> features cross? >>> >>> One method I've considered is to draw the roads and parking lots >as >>> polygons in the same layer? It would make drawing the >>roads >>> non-trivial, but the problem with outlines would be eliminated. >>> >>> Shane >>> >>> _______________________________________________ >>> Qgis-user mailing list >>> [email protected] >>> http://lists.osgeo.org/mailman/listinfo/qgis-user >> >> >> >> [email protected] > > > >-- >Bernd Vogelgesang >Siedlerstraße 2 >91083 Baiersdorf/Igelsdorf >Tel: 09133-825374 > >------------------------------------------------------------------------ > >From: Nicolas Cadieux <[email protected]> >To: [email protected] >Sent: Thu Jul 30 23:07:50 BST 2015 >Subject: Re: [Qgis-user] Layer question > >Hi, >You can play with the layer blending. You can use "multiply" , >"add", "subtract"... (something like that, I am not in front of a >computer). There are also the same blending options in the vector >object styling so that you can select what happens when two objects >intersect in the same layer. >Maybe that could help? >Nicolas Cadieux M.Sc. >Les Entreprises Archéotec inc.  >8548, rue Saint-Denis Montréal H2P 2H2 >Téléphone: 514.381.5112  Fax: 514.381.4995 >www.archeotec.ca >On Jul 30, 2015 5:45 PM, "berndv. [via OSGeo.org]" ><[email protected]> wrote: > > > > >Hi Shane, I think without a screenshot, we have no chance to really get >an idea what it's all about. Best to use a service like >http://imgur.com/ and post the link cause the list will bounce too >heavy attachments. Bernd Am 30.07.2015, 23:11 Uhr, schrieb Tom Lennon >< [hidden email] >: <blockquote style="border-left:2px >solid #cccccc;padding:0 1em" style="margin:0 0 >0.8ex;border-left:#0000ff 2px solid;padding-left:1ex"> Hi >Shane: Have you tried moving the parking lot layer to below the road >layer? That way roads over parking lots would always show. Tom On Thu, >Jul 30, 2015 at 3:05 PM, Shane < [hidden email] > wrote: ><blockquote style="border-left:2px solid #cccccc;padding:0 >1em" style="margin:0 0 0 0.8ex;border-left:1px #ccc >solid;padding-left:1ex"> Hi group, > > I have a layer with roads which are lines having a style of gray >with thin black outlines on either side. Another layer (parking lots) >has polygons having the same color as the roads but not outlined. The >parking lot layer is above the road layer in rendering order. So road >outlines are hidden by the parking lot layer when a parking lot >intersects a road. > > Here's the trouble - having parking lots with no outline, but >roads with outlines looks odd. Is there some way to have the outlines >of both road and parking lot layers removed from rendering when these >two features cross? > > One method I've considered is to draw the roads and parking lots >as polygons in the same layer? It would make drawing the roads >non-trivial, but the problem with outlines would be eliminated. > > Shane > >_______________________________________________ >Qgis-user mailing list >[hidden email] >http://lists.osgeo.org/mailman/listinfo/qgis-user >-- [hidden email] > >-- Bernd Vogelgesang Siedlerstraße 2 91083 Baiersdorf/Igelsdorf Tel: >09133-825374 _______________________________________________ >Qgis-user mailing list >[hidden email] >http://lists.osgeo.org/mailman/listinfo/qgis-user > > > > > > > > > If you reply to this email, your message will be added to the >discussion below: > > http://osgeo-org.1560.x6.nabble.com/Layer-question-tp5217849p5217887.html > > > > To start a new topic under Quantum GIS - User, email >ml-node+s1560n4125267h38@n6.nabble.com > To unsubscribe from Quantum GIS - User, click here . > NAML > > > > >-- >View this message in context: >http://osgeo-org.1560.x6.nabble.com/Layer-question-tp5217849p5217890.html >Sent from the Quantum GIS - User mailing list archive at Nabble.com. > >------------------------------------------------------------------------ > >From: Nick Papadonis <[email protected]> >To: "Håvard Tveite" <[email protected]> >Cc: [email protected] >Sent: Fri Jul 31 00:45:56 BST 2015 >Subject: Re: [Qgis-user] How to convert raster routes into vector >format? > >Hi Havard, > >Unfortunately, the expression below results in a complete black TIFF. >I am referencing the correct layer. Any ideas? > >Thanks >Nick > >> On Jul 29, 2015, at 4:34 PM, Håvard Tveite <[email protected]> >wrote: >> >> With QGIS 2.10, the following should work (probably also OK >> for earlier versions). >> >> Check the band values of your colour using the info button, >> and use the values in the expression below (assuming the >> name of your raster layer is yourraster) instead of 116, 20 >> and 31: >> >> ("yourraster@1" = 116 AND "yourraster@2" = 20 AND "yourraster@3" = >31) * 1 >> >> This should give you a binary raster with 1 in the pixels >> that have your colour and 0 in the pixels with other colours. >> >> In the style dialogue you can use the following to see the >> resulting binary image: >> Colour gradient: "white to black" >> Min: 0 >> Max: 1 >> >> You should be able to use r.thin on that image, but I am not >> able to test this now, as I am on Ubuntu, and have not been >> able to get GRASS to work through Processing on that platform >> for QGIS 2.10. >> >> Håvard >> >> On 29. juli 2015 16:40, Nick Papadonis wrote: >>> Hi Håvard, >>> >>> I found the raster calculator and read the online manual for it, >however am still a bit lost. I was also playing with the Style >properties and color bands last night to try to accomplish this. I was >unable to get a single binary image with the single color (red in this >case). I think the understand the r.thin suggestion and that it will >thin the single color thick lines for vectorization. Appreciate if you >can expand on obtaining a binary skeleton of the one color of the >trails. >>> >>> Thanks again, >>> Nick >>> >>>> On Jul 29, 2015, at 7:18 AM, Havard Tveite <[email protected]> >wrote: >>>> >>>> If you are going to use GRASS r.to.vect (for instance through QGIS >>>> Processing), you will need a binary skeleton image. >>>> You could get one by using the raster calculator to extract >>>> your single colour as a binary image, and then GRASS r.thin >>>> (available in QGIS Processing) to get the skeleton. >>>> >>>> Håvard >>>> >>>> On 29/7/2015 8:36:AM, Nick Papadonis wrote: >>>>> Hi Folks, >>>>> >>>>> I have a map with numerous trails in a single color and would like >to vectorize these. Is there a mode Qgis can be placed in such that a >color can be selected for inclusion in the vectorization process? I.e. >to make converting these routes to vector format easier? >>>>> >>>>> Thanks again >>>>> _______________________________________________ >>>>> Qgis-user mailing list >>>>> [email protected] >>>>> http://lists.osgeo.org/mailman/listinfo/qgis-user >>>>> >>> > > > > >------------------------------------------------------------------------ > >From: Nick Papadonis <[email protected]> >To: [email protected] >Sent: Fri Jul 31 02:07:44 BST 2015 >Subject: [Qgis-user] Raster Calculator Expression to determine color > >HI Folks, > >I’m trying to use the following expression to pick up the red colored >routes on a map in which I used the info pointer tool to get the band >values for the color. > >(“m@1" < 238 AND “m@1" > 213 AND “m@2" < 123 AND “m@2" > 98 AND “m@3" < >125 AND “m@3" < 99) * 1 > >Unfortunately, when this expression is used the resulting map is black >with no other pixels for the detected color. > >If I break down this expression to a simple “greater than” line for >single band, then things work. > >Does anyone know where this expression needs to be corrected? > >Thanks again, >Nick > > >------------------------------------------------------------------------ > >From: Nyall Dawson <[email protected]> >To: Nick Papadonis <[email protected]> >Cc: [email protected] >Sent: Fri Jul 31 02:29:34 BST 2015 >Subject: Re: [Qgis-user] Raster Calculator Expression to determine >color > >On 31 Jul 2015 11:07 am, "Nick Papadonis" <[email protected]> wrote: >> >> HI Folks, >> >> I’m trying to use the following expression to pick up the red colored >routes on a map in which I used the info pointer tool to get the band >values for the color. >> >> (“m@1" < 238 AND “m@1" > 213 AND “m@2" < 123 AND “m@2" > 98 AND “m@3" >< >125 AND “m@3" < 99) * 1 > >Should that last check be "m@3" > 99? > >Nyall > >> >> Unfortunately, when this expression is used the resulting map is >black >with no other pixels for the detected color. >> >> If I break down this expression to a simple “greater than” line for >single band, then things work. >> >> Does anyone know where this expression needs to be corrected? >> >> Thanks again, >> Nick >> _______________________________________________ >> Qgis-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-user > > >------------------------------------------------------------------------ > >From: Nick Papadonis <[email protected]> >To: Nyall Dawson <[email protected]> >Cc: [email protected] >Sent: Fri Jul 31 02:30:44 BST 2015 >Subject: Re: [Qgis-user] Raster Calculator Expression to determine >color > > >> On Jul 30, 2015, at 9:29 PM, Nyall Dawson <[email protected]> >wrote: >> >> >> On 31 Jul 2015 11:07 am, "Nick Papadonis" <[email protected] ><mailto:[email protected]>> wrote: >> > >> > HI Folks, >> > >> > I’m trying to use the following expression to pick up the red >colored routes on a map in which I used the info pointer tool to get >the band values for the color. >> > >> > (“m@1" < 238 AND “m@1" > 213 AND “m@2" < 123 AND “m@2" > 98 AND >“m@3" < 125 AND “m@3" < 99) * 1 >> >> Should that last check be "m@3" > 99? >> >> >Yeah, I changed that and still same results. If I specify on > and >remove the < expressions, then everything works. Very odd considering >the color is within the range above (with the line you referenced >fixed). > >Thanks >> Nyall >> >> > >> > Unfortunately, when this expression is used the resulting map is >black with no other pixels for the detected color. >> > >> > If I break down this expression to a simple “greater than” line for >single band, then things work. >> > >> > Does anyone know where this expression needs to be corrected? >> > >> > Thanks again, >> > Nick >> > _______________________________________________ >> > Qgis-user mailing list >> > [email protected] <mailto:[email protected]> >> > http://lists.osgeo.org/mailman/listinfo/qgis-user ><http://lists.osgeo.org/mailman/listinfo/qgis-user> > > >------------------------------------------------------------------------ > >From: Nick Papadonis <[email protected]> >To: Nyall Dawson <[email protected]>, [email protected] >Sent: Fri Jul 31 02:56:24 BST 2015 >Subject: Re: [Qgis-user] Raster Calculator Expression to determine >color > > >> On Jul 30, 2015, at 9:29 PM, Nyall Dawson <[email protected]> >wrote: >> On 31 Jul 2015 11:07 am, "Nick Papadonis" <[email protected] ><mailto:[email protected]>> wrote: >> > >> > HI Folks, >> > >> > I’m trying to use the following expression to pick up the red >colored routes on a map in which I used the info pointer tool to get >the band values for the color. >> > >> > (“m@1" < 238 AND “m@1" > 213 AND “m@2" < 123 AND “m@2" > 98 AND >“m@3" < 125 AND “m@3" < 99) * 1 >> >> Should that last check be "m@3" > 99? >> >> > >I corrected above to: >(“m@1" < 238 AND “m@1" > 213 AND “m@2" < 123 AND “m@2" > 98 AND “m@3" < >125 AND “m@3” > 99) * 1 > >with the same results which is black output tiff. > >I then tried individual expressions for each band as separate steps >(sanity check): >(“m@1" < 238 AND “m@1" > 213) * 1 >(“m@2" < 123 AND “m@2" > 98) * 1 >(“m@3" < 125 AND “m@3” > 99) * 1 > >These all produce a masked image, however masked incorrectly because >I’m evaluating only a single band in the Raster Calculator. > >When I combine evaluation of bands as above or below to pick pixels in >color range: > >((“m@1" < 238 AND “m@1" > 210) AND (“m@2" < 123 AND “m@2" > 94) AND >(“m@3" < 130 AND “m@3" > 98)) * 1 > >I get a black image with no matches. I expected at least one pixel >identified using this expression because I evaluate a pixel at 224, >108, 115 and there are many other pixels in above range. > >Does anyone know if my expression needs correction or the Raster >Calculator can only evaluate a single band in the expression? > >Thanks again, >Nick > >> Nyall >> >> > >> > Unfortunately, when this expression is used the resulting map is >black with no other pixels for the detected color. >> > >> > If I break down this expression to a simple “greater than” line for >single band, then things work. >> > >> > Does anyone know where this expression needs to be corrected? >> > >> > Thanks again, >> > Nick >> > _______________________________________________ >> > Qgis-user mailing list >> > [email protected] <mailto:[email protected]> >> > http://lists.osgeo.org/mailman/listinfo/qgis-user ><http://lists.osgeo.org/mailman/listinfo/qgis-user> > > >------------------------------------------------------------------------ > >From: Nick Papadonis <[email protected]> >To: [email protected] >Sent: Fri Jul 31 05:39:12 BST 2015 >Subject: Re: [Qgis-user] Raster Calculator bug? > >Folks, > >I’m using QGIS 10.1. The following expressions result in a black >raster of 0’s, when I expected only red pixels to appears in the binary >image indicating routes on a map: > >a) (“m@1" < 238 AND “m@1" > 213 AND “m@2" < 123 AND “m@2" > 98 AND >“m@3" < 125 AND “m@3” > 99) * 1 >b) ((“m@1" < 238 AND “m@1" > 210) * 1) * ((“m@2" < 123 AND “m@2" > 94) >* 1) * ((“m@3" < 130 AND “m@3" > 98) * 1) > >I then tried the following individual expressions for each band as >separate steps (sanity check) and they work to cover the pixels in >range: >c) (“m@1" < 238 AND “m@1" > 213) * 1 >d) (“m@2" < 123 AND “m@2" > 98) * 1 >e) (“m@3" < 125 AND “m@3” > 99) * 1 > >I then tried the following expression which appears to create a proper >greyscale image focusing on the red pixels. I replaced the >multiplication with addition to see what was happening: >f) ((“m@1" < 238 AND “m@1" > 210) * 1) + ((“m@2" < 123 AND “m@2" > 94) >* 1) + ((“m@3" < 130 AND “m@3" > 98) * 1) > >The resulting raster has a Min = 0 and Max = 1.998. I was expecting it >to be Min = 0 and Max = 3. The value of 3 would indicate all 3 bands >were positive on color match. I then go to the layer properties and >load calculate min/max again and it is Min = 0 and Max = 3. I tried to >change the min/max settings on they layer and these settings will not >stay set. The layer goes back to Max = 1.998. What’s even more odd is >the max being a floating point number. I suspect that may be part of >the issue. Anyone know why this is the case for integer band values? >Has anyone successfully used the Raster Calculator to perform this sort >of work before? > >Thanks again, >Nick > > >------------------------------------------------------------------------ > >_______________________________________________ >Qgis-user mailing list >[email protected] >http://lists.osgeo.org/mailman/listinfo/qgis-user -- Jonathan Webb Freelance GIS specialist 07941 921905 www.jwebbgis.co.uk
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