[mapserver-users] MapServer/MapCache vector tile test with max/min scale denominator

[Lime, Steve D (MNIT)]

Hi Martin: Hmmm... I'm surprised it works one way and not the other. I can only guess that a scale denominator is not being computed in one case versus the other. I can confirm the necessary check is being done in the MVT code (via msLayerIsVisible()) but if the basic information that function needs is not available then that's the problem. 

I created a ticket: https://github.com/mapserver/mapserver/issues/5714

--Steve

-----Original Message-----
From: mapserver-users [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Martin Høgh
Sent: Saturday, November 17, 2018 6:05 AM
To: mapserver-users at lists.osgeo.org
Subject: [mapserver-users] MapServer/MapCache vector tile test with max/min scale denominator

I've tested MapServer and MapCache with vector tiles using this 
MapServer branch:

https://github.com/sdlime/mapserver/tree/vector-tiles

And this MapCache PR:

https://github.com/mapserver/mapcache/pull/166

And it works.

I've also tested the layer level "max/min scale denominator" setting in 
MapServer to filter out layers in the vector tiles for different zoom 
levels, which also works when using Mapserver directly with the classic 
cgi interface, but not when using MapCache.

The max/min scale denominator kicks in with something likes this:

http://127.0.0.1/cgi-bin/mapserv.fcgi?map=/my_mapfile.map&mode=tile&tilemode=gmap&tile={x}+{y}+{z}&layers=all&map.imagetype=mvt

But when requesting tiles through MapCache the max/min scale denominator 
doesn't kicks in at any zoom levels.

I believe its because MapCache is requesting tiles through the WMS 
interface of MapServer and for some reason that behaves differently?

The definition in the MapCache file is

<!—define a new raw format to use for MapBox vector tiles -->

<format name="MVT" type="RAW">

    <extension>mvt</extension>

<mime_type>application/vnd.mapbox-vector-tile</mime_type>

</format>



<!—this WMS source fetches MapBox vector tiles (.mvt) -->

<source name="wms_mvt" type="wms">

   <http>

     <url>http://localhost/cgi-bin/mapserv.fcgi?</url>

   </http>

   <getmap>

     <params>

       <LAYERS>public</LAYERS>

<FORMAT>application/vnd.mapbox-vector-tile</FORMAT>

       <MAP>/my_mapfile.map </MAP>

     </params>

   </getmap>

</source>



<!—and finally the tileset -->

<tileset name="mvt">

   <source>wms_mvt</source>

   <grid>g</grid>

   <cache>disk</cache>

   <format>MVT</format>

</tileset>



Cheers

-- 
Martin Høgh
MapCentia ApS

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