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

[ndrw]

Hi Rob,

Good stuff, it's definitely worthwhile. Thinner lines could work better 
(for me 1px would be perfect), especially that the max zoom stops at 17. 
You could perhaps consider increasing the max zoom a notch as well.

Are the numbers in wms tiles UPRNs? If so, you could consider displaying 
them as well.

Best regards,

ndrw6

On 17/10/2020 00:20, Rob Nickerson 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}
>
> Best regards,
> *Rob*
>
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