Generate Layer with Countries names

[BenOnTrack]

I'm trying to use the ne_10m_admin_0_countries from Natural Earth Data, which is supposed to contain countries name (and ISO) according to the .dbf file.

I've added "source_columns":true in my tilemaker file .config while my tilemaker .process is

function init_function()
end
function exit_function()
end

node_keys = {}
function node_function()
end

function way_function()
end

function attribute_function(attr,layer)
	return attr
end

and then create a style in my maplibre-gl style

 {
      "id": "countries",
      "type": "symbol",
      "source": "countries",
      "source-layer": "countries",
      "metadata": {
        "switch": false,
        "clickable": true
      },
      "layout": {
        "text-field": "{ADMIN} {ISO_A2} {ISO_A3}",
        "text-font": [
          "Noto Sans Italic"
        ],
        "text-max-width": 6.25,
        "visibility": "visible"
      },
      "paint": {
        "text-color": "#334",
        "text-halo-blur": 1,
        "text-halo-color": "rgba(255,255,255,0.8)",
        "text-halo-width": 2
      }
    }

but got nothing rendered... any hints ?

[cldellow]

Step 1: Is tilemaker emitting the data?

If you are unsure, you can:

1. output a .pmtiles file
2. open PMTiles Viewer and point it at your local PMTiles file
3. zoom in to the zoom level where you expect to see it - maybe disable other layers in the viewer to make it more obvious
4. enable show attributes option and hover over the tile

If you don't see the object in step 3, then tilemaker is not emitting anything. Put a print(...) in your attribute_function to see if it's even getting called.

If you see the object in step 3, but don't see the expected attributes in step 4, then tilemaker's emitting the shape, but not the attributes.

If either case applies, further debugging will require that you also include the relevant portion of your config.json -- the layers entry and the overall minzoom / maxzoom values.

[BenOnTrack]

Thank you for your quick feedback. I've been working with .mbtiles and can't find any 'debugging' tool that would be able to analyse the file without the need to generate a style.json. I'll then try to output a .pmtiles to check if the data is actually output. I'm not entirely sure about the .process file if I need to code anything in the 'node_function' but it doesn't look like I should since I'm requesting all tables from the initial .shp to be printed out. It might as well be that the natural earth data I'm using is actually not including the name of the countries (but then it would mean that their description of the content of the file is wrong though...)

…

On Sep 11, 2024, 08:43 +0900, Colin Dellow ***@***.***>, wrote: Step 1: Is tilemaker emitting the data? If you are unsure, you can: 1. output a .pmtiles file 2. open PMTiles Viewer and point it at your local PMTiles file 3. zoom in to the zoom level where you expect to see it - maybe disable other layers in the viewer to make it more obvious 4. enable show attributes option and hover over the tile If you don't see the object in step 3, then tilemaker is not emitting anything. Put a print(...) in your attribute_function to see if it's even getting called. If you see the object in step 3, but don't see the expected attributes in step 4, then tilemaker's emitting the shape, but not the attributes. If either case applies, further debugging will require that you also include the relevant portion of your config.json -- the layers entry and the overall minzoom / maxzoom values. — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you authored the thread.Message ID: ***@***.***>

[cldellow]

Yes, the process.lua file looks fine. If there's an issue it'll be in the config.json or the style file.

This is what I see when I use the pmtiles inspector on that NE data, just passing through the data from the shapefile untransformed, as you are trying to do:

Annoyingly, the inspector doesn't seem to sort the attributes, but ADMIN, ISO_A2 and ISO_A3 are all there.

[cldellow]

If you can reproduce this issue, can you please create a gist that contains your process.lua, config.json and style.json files? That will make this much less of a game of telephone.

[BenOnTrack]

I will try to reproduce the issue. In the meantime, when you mention it worked on your end,
for the NE do you use:https://www.naturalearthdata.com/downloads/10m-cultural-vectors/10m-admin-0-countries/
And for the .process file do you have

function attribute_function(attr,layer)
	return attr
end

or

function attribute_function(attr,layer)
end

I've also changed the .config to
"source_columns": ["ADMIN"]
to remove un-necessary data.

Anyway I'll re-try the entire process and will post all full files.

[cldellow]

Yes, that's the NE data I'm using.

My config files are at: https://gist.github.com/cldellow/1483395f32d34ae2454148d9e4fb9988

Full disclosure: I haven't tried to author a style file that renders the labels, I'm relying on the fact that pmtiles.io shows the ADMIN/ISO_A2/ISO_A3 data when looking at the pmtiles file.

[BenOnTrack]

Thank you.
But nvm, tl;dr I've found the issue - my style post-processing was slightly too fancy and only works with {name} id, hence discarding the initial {ADMIN}!

thanks for the support :)
I'm keeping this thread open for the LayerAsCentroid proposal for the attribute

[cldellow]

phew, good to hear!

[BenOnTrack]

The remaining issue though is the way it's logged within the tiles - it looks like it's a polygon text rather than a node. So i'm stil convinced there's a better way to do ?

[cldellow]

tilemaker's support for shapefiles/GeoJSON passes the underlying shape into the output pmtiles/mbtiles as-is.

So the NE data presumably has 1 multipolygon for Japan, which gets emitted as such. Most map renderers do a poor job labelling polygons (see, e.g. mapbox/mapbox-gl-js#7846)

The workaround is to explicitly produce a point to use as the anchor for the label. You'll have to use some other tool to transform the shape to achieve that: tilemaker's LayerAsCentroid function isn't available in the context of attribute_function.

That might be a useful extension, though. I wonder if @systemed has thoughts?

It looks like there's already a magic meta key called _minzoom:

tilemaker/docs/CONFIGURATION.md

Line 212 in eab08d1

To set the minimum zoom level at which an individual feature is rendered, use `attribute_function` to set a `_minzoom` value in your return table.

Maybe there could be another magic meta key called _centroid which, if truthy, emits a point using the polylabel algorithm.

[BenOnTrack]

I was exactly thinking about that too :-)