[talk-au] Talk-au Digest, Vol 65, Issue 1

Stephen Kelly steve at sjk.net.au
Thu Nov 1 07:52:47 GMT 2012


hi,

I can think of two easier ways of doing this that setting rendering hints-
one would be to change the rendering rules for set geographical areas, such
as tanami track, ie when rendering within this geographic area use these
rules for this zoom.

A second but more complicated way to do it would be to query your database,
see how dense an area is for data, then decide your rendering rules, so
when it does down town sydney (dense data) - footpaths don't get shown,
when you render tanami track (very little data) - footpaths are rendered
and various options in between the two.

This way it can be done programmatically and you don't need to add / edit
the data.




On Thu, Nov 1, 2012 at 4:10 PM, <talk-au-request at openstreetmap.org> wrote:

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> Today's Topics:
>
>    1. Optimising map rendering for recreational use (Li Xia)
>    2. Re: Optimising map rendering for recreational use (Ben Kelley)
>    3. Re: Optimising map rendering for recreational use (Li Xia)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 1 Nov 2012 15:01:11 +1100
> From: Li Xia <lisxia1982 at gmail.com>
> To: talk-au at openstreetmap.org
> Subject: [talk-au] Optimising map rendering for recreational use
> Message-ID: <09EE5D87-FA98-495A-AF9D-A60585482A5B at gmail.com>
> Content-Type: text/plain; charset="us-ascii"
>
> Hey everyone, have an idea about map rendering and want to get your
> thoughts.
>
> One of the challenges is in rendering a useful map for recreational use is
> displaying roads, tracks, trails and to some degree water lines at
> appropriate zoom levels in more remote regions where the density is lower
> compared with urban regions.
>
> In my opinion, most map service online services or offline vector engine
> experience the same issue. Here are some illustrations of the issue, by
> comparing Google / OSM / Raster map of the same region:
>
> Google
>
> OSM
>
> Raster map
>
> As you can clearly see, at that zoom level, there's no deal on either OSM
> or Google maps, where as the raster map is useful. yes you can zoom in on
> Google or OSM, but with a smaller viewing port, orientation is more
> difficult and you loose that overview which is try handy for trip planning.
>
> By using a tag specific for rendering purposes, this issue can be
> overcome. Rendering engines can take advantage of these tags to "optimise"
> rendering of various regions.
>
> The tags are fairly self explanatory. By tagging a road with
> render_as:trunk, this feature can be rendered at the same zoom level as a
> trench road. Each class of road will have it's own tag so if a
> highway:territory should be rendered at the same zoom level as a primary,
> then tag render_as:tertiary.
>
> What do you guys think?
>
> Cheers
>
> Li.
>
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> ------------------------------
>
> Message: 2
> Date: Thu, 1 Nov 2012 15:31:50 +1100
> From: Ben Kelley <ben.kelley at gmail.com>
> To: Li Xia <lisxia1982 at gmail.com>
> Cc: talk-au at openstreetmap.org
> Subject: Re: [talk-au] Optimising map rendering for recreational use
> Message-ID:
>         <CAE4-2TKUbM=
> ieK-a3q2WmULFY5wkxpyOGtDSM3DS-zaoa+yfrQ at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi.
>
> I think tagging for the renderer is a bad idea.
>
> Essentially you are talking more about render hints, but I think that
> becomes a matter of preference pretty fast. Especially when OSM data can be
> rendered in a number of ways.
>
> I think it is worth considering what about a road makes you want to render
> it as a different type of road.
>
>   - Ben Kelley.
>  On Nov 1, 2012 3:01 PM, "Li Xia" <lisxia1982 at gmail.com> wrote:
>
> > Hey everyone, have an idea about map rendering and want to get your
> > thoughts.
> >
> > One of the challenges is in rendering a useful map for recreational use
> is
> > displaying roads, tracks, trails and to some degree water lines at
> > appropriate zoom levels in more remote regions where the density is lower
> > compared with urban regions.
> >
> > In my opinion, most map service online services or offline vector engine
> > experience the same issue. Here are some illustrations of the issue, by
> > comparing Google / OSM / Raster map of the same region:
> >
> > Google<
> http://www.mud-maps.com/li_temp/1211/Screen%20Shot%202012-10-25%20at%204.42.31%20PM.png
> >
> >
> > OSM<
> http://www.mud-maps.com/li_temp/1211/Screen%20Shot%202012-10-25%20at%204.42.26%20PM.png
> >
> >
> > Raster map<
> http://www.mud-maps.com/li_temp/1211/Screen%20Shot%202012-10-25%20at%204.42.22%20PM.png
> >
> >
> > As you can clearly see, at that zoom level, there's no deal on either OSM
> > or Google maps, where as the raster map is useful. yes you can zoom in on
> > Google or OSM, but with a smaller viewing port, orientation is more
> > difficult and you loose that overview which is try handy for trip
> planning.
> >
> > By using a tag specific for rendering purposes, this issue can be
> > overcome. Rendering engines can take advantage of these tags to
> "optimise"
> > rendering of various regions.
> >
> > The tags are fairly self explanatory. By tagging a road with
> > render_as:trunk, this feature can be rendered at the same zoom level as a
> > trench road. Each class of road will have it's own tag so if a
> > highway:territory should be rendered at the same zoom level as a primary,
> > then tag render_as:tertiary.
> >
> > What do you guys think?
> >
> > Cheers
> >
> > Li.
> >
> >
> > _______________________________________________
> > Talk-au mailing list
> > Talk-au at openstreetmap.org
> > http://lists.openstreetmap.org/listinfo/talk-au
> >
> >
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> ------------------------------
>
> Message: 3
> Date: Thu, 1 Nov 2012 17:09:58 +1100
> From: Li Xia <lisxia1982 at gmail.com>
> To: Ben Kelley <ben.kelley at gmail.com>
> Cc: talk-au at openstreetmap.org
> Subject: Re: [talk-au] Optimising map rendering for recreational use
> Message-ID: <5778FC56-1E77-4D84-B259-39D1231068EA at gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hey Ben and others,
>
> Yep, spot on, rendering hints but only related to zoom levels. I realise
> that it's matter of opinion what roads to be rendered at what levels etc
> and why rendering hints are not considered "factual data" and not preferred.
>
> Changing the road classification is an option but are likely to cause side
> effects. For example, tagging what is a territory road as a primary so that
> it will be rendered earlier on in the zoom level has the potential of
> polluting the data, making it less useful for other purposes such as
> routing etc.
>
> Another positive of the rendering hints approach is that the tags
> themselves are completely optional so it's up to the rendering engine to
> take advantage of them. If ignored, it's like they
>
> Also these tags are only really needed in more regional / outback areas,
> such as the Great central rd, Tanami track, French line etc so it's
> lightweight and won't add much size to the database.
>
> I plan to start a new project for mapping off road and regional areas of
> Australia and these rendering hints will certainly make a huge difference
> in rendering. There are already quiet a few of interested in this project
> and was planning to start a new project page on the Aus Wiki to coordinate
> this effort. We were hoping to include the rendering tags among the guild
> line and hope you guys agree.
>
> Li
>
>
> On 01/11/2012, at 3:31 PM, Ben Kelley wrote:
>
> > Hi.
> >
> > I think tagging for the renderer is a bad idea.
> >
> > Essentially you are talking more about render hints, but I think that
> becomes a matter of preference pretty fast. Especially when OSM data can be
> rendered in a number of ways.
> >
> > I think it is worth considering what about a road makes you want to
> render it as a different type of road.
> >
> >   - Ben Kelley.
> > On Nov 1, 2012 3:01 PM, "Li Xia" <lisxia1982 at gmail.com> wrote:
> > Hey everyone, have an idea about map rendering and want to get your
> thoughts.
> >
> > One of the challenges is in rendering a useful map for recreational use
> is displaying roads, tracks, trails and to some degree water lines at
> appropriate zoom levels in more remote regions where the density is lower
> compared with urban regions.
> >
> > In my opinion, most map service online services or offline vector engine
> experience the same issue. Here are some illustrations of the issue, by
> comparing Google / OSM / Raster map of the same region:
> >
> > Google
> >
> > OSM
> >
> > Raster map
> >
> > As you can clearly see, at that zoom level, there's no deal on either
> OSM or Google maps, where as the raster map is useful. yes you can zoom in
> on Google or OSM, but with a smaller viewing port, orientation is more
> difficult and you loose that overview which is try handy for trip planning.
> >
> > By using a tag specific for rendering purposes, this issue can be
> overcome. Rendering engines can take advantage of these tags to "optimise"
> rendering of various regions.
> >
> > The tags are fairly self explanatory. By tagging a road with
> render_as:trunk, this feature can be rendered at the same zoom level as a
> trench road. Each class of road will have it's own tag so if a
> highway:territory should be rendered at the same zoom level as a primary,
> then tag render_as:tertiary.
> >
> > What do you guys think?
> >
> > Cheers
> >
> > Li.
> >
> >
> > _______________________________________________
> > Talk-au mailing list
> > Talk-au at openstreetmap.org
> > http://lists.openstreetmap.org/listinfo/talk-au
> >
>
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