[Talk-GB] OSM UK's first tile layer

[Rob Nickerson]

Hi all,

To address this and some of the other questions:

>Can JOSM and iD display Mapbox .pbf vector tiles?
I don't think JOSM can which is a big shame as it would make it much easier
to host these sort of layers with minimal overhead.

>ensure any transformation from OSGB grid coordinates to WGS84 is accurate
enough
Yes indeed. Currently I used QGIS to transform the data for York however I
see that Mapnik can do the transform itself. For a complete GB dataset I
intend to download all files and bring them together to pass to Mapnik. It
probably then makes sense to have Mapnik do the transform. Any details on
what transformation I should be using would be much appreciated. Likewise
if you know a location that gets a big error if done wrong, that would help
me check.

>Thinner lines could work better
Yes, I think so too.

>consider increasing the max zoom a notch as well
Hopefully the new OSM UK board can investigate that as it will need a
beefier server so would push costs up.

>Are the numbers in wms tiles UPRNs?
My understanding is that they are not. That level of coordination would be
amazing but we're not there with Open Data yet!

P.S. If anyone is aware of the equivalent data for Northern Ireland, Isle
of Man or the Channel Islands, please let me know.

Best regards,
*Rob*


On Sat, 17 Oct 2020 at 08:16, Jez Nicholson <jez.nicholson at gmail.com> wrote:

> Nice one. I've been wanting to do this for ages.
>
> Re: file size. Can JOSM and iD display Mapbox .pbf vector tiles? These
> would be smaller.
>
> On Sat, 17 Oct 2020, 00:22 Rob Nickerson, <rob.j.nickerson at gmail.com>
> wrote:
>
>> Hi all,
>>
>> Just in time for the AGM, I have just published OSM UK's first tile
>> layer. No don't get too excited it is not a full map render. Instead I have
>> produced a very simple tiling of the Land Registry polygon data now that
>> this is under the OGL Open Data Licence. My view is that this is a good
>> layer to align our mapping too - i.e. when tracing from imagery we should
>> first align the imagery to the Land Registry polygon layer before tracing
>> from the imagery.
>>
>> The tile URL for JOSM is:
>> tms[13,17]:http://tiles.osmuk.org/LRpolygons/{zoom}/{x}/{y}.png
>>
>> And for now this is *York only* as an example.
>>
>> Feedback that I would appreciate:
>>
>>    - Is this worthwhile?
>>    - Do you agree that it makes sense for us to all try to align our
>>    mapping to this (i.e. apply imagery offsets to align imagery to this before
>>    tracing)?
>>    - The style is very simple with just a 4 pixel red line. Is this
>>    sufficient? What changes can be made?
>>    - Any tips on how to keep the PNG file sizes as small as possible?
>>    For now I am using the Mapnik rule "png8:c=2:t=1:m=o". Is there anything
>>    that can yield smaller file sizes?
>>    - What max zoom is worthwhile? Currently it goes to 17, is this
>>    enough?
>>
>> Our plan would be to pre-render all the tiles and host them on our site.
>> The data doesn't change much so we would only re-render on request or once
>> a year. My estimate is that we'd need 35GB for tiles to zoom level 17, and
>> 133 GB to get everything to zoom 18. Our current server is on the small
>> side with just 512MB memory and a 100GB disk allowance. It is unsuitable
>> for on the fly rendering and we'd need more disk space to get the level 18
>> zoom. A beefier server is of course possible but any bump in specs comes
>> with an equal bump in costs so worth checking this is worthwhile before
>> proceeding.
>>
>> P.S. The Land Registry themselves host this data on a WMS service rather
>> than a TMS (tile) service. This makes it possible to zoom much further in.
>> If you want to have a look at that detail you can use their website or
>> (temporarily) use the following URL in JOSM. Please don't use this for
>> mapping as we don't have permission to use their WMS service
>>
>> wms:
>> http://inspire.landregistry.gov.uk/inspire/ows?SERVICE=WMS&FORMATS=image%2Fpng&LAYERS=inspire%3ACP.CadastralParcel&FORMAT=image%2Fpng&TRANSPARENT=true&VERSION=1.1.1&REQUEST=GetMap&STYLES=&INFO_FORMAT=application%2Fvnd.ogc.gml&EXCEPTIONS=XML&_OLSALT=0.789927776902914&SRS={proj}&BBOX={bbox}&WIDTH={width}&HEIGHT={height}
>> <http://inspire.landregistry.gov.uk/inspire/ows?SERVICE=WMS&FORMATS=image%2Fpng&LAYERS=inspire%3ACP.CadastralParcel&FORMAT=image%2Fpng&TRANSPARENT=true&VERSION=1.1.1&REQUEST=GetMap&STYLES=&INFO_FORMAT=application%2Fvnd.ogc.gml&EXCEPTIONS=XML&_OLSALT=0.789927776902914&SRS=%7Bproj%7D&BBOX=%7Bbbox%7D&WIDTH=%7Bwidth%7D&HEIGHT=%7Bheight%7D>
>>
>> Best regards,
>> *Rob*
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>>
>
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