Add a new adhoc feature that doesn't correspond to SourceFeature

[adjourn]

Hi, sorry for the wonky title, so many new terms, I find it hard to express myself.
I'm trying to figure out how I could give a personal touch to maps. The holy grain seems to be manually added feature/geometry.

Let's take a simple example:

At some low zoom level, let's say 6, river (Multi)LineString are not added since it's too far away. However there are some very major rivers and their (Multi)Polygon are added. Example goal is to show river name on them. I could just write an if to match river name and allow LineString for specific rivers for specific zoom but from that distance OSM lines are too detailed, too many tiny bends, etc to render text on them. I tried line simplification but most rivers are still unworkable, literally tried different settings for 4 hours straight.

My conclusion: draw my own very simple LineSring with manual coordinates and incude it only for zoom level 6.

This does replace the geomentry but for all zoom levels:

// in source handler
if (sourceFeature.getTag("name").toString().equals("Some Major River")) {
  var line = Utils.createLineString(new double[] { /* ... */ };  // <- uses GeoUtils.JTS_FACTORY.createLineString
  feat = features.geometry(this.name(), line);
} else {
  feat = features.line(this.name());
}

I have 2 questions, technically only one of them is needed to solve my example and I would be happy with that answer but I feel like both would be very powerful tools in my arsenal, I would gladly get an answer to both:

1. How can I add a brand new feature to certain layer, without any correlation to OSM data?
   • I prefer the code way, there's probably a 2 months worth of learning some tools and formats I haven't even heard about where I can add my own GeoJSON and use it as planetiler source.. If there's a simple workflow, I wouldn't mind hints to that, but code for sure
   • To support my previous point, this is about few little personal touches here and there, not industrial scale extra data
2. How can I replace geometry for only 1 zoom level for the OSM derived feature?

I'm not even sure if I can properly express the first question.. If clarification is needed, I'll gladly comply.

[wipfli]

I would add a geojson or geopackage source containing what you need.

[wipfli]

If you want to go with in-code, use minzoom and maxzoom:

// in source handler
if (sourceFeature.getTag("name").toString().equals("Some Major River")) {
  var line = Utils.createLineString(new double[] { /* ... */ };  // <- uses GeoUtils.JTS_FACTORY.createLineString
  feat = features.geometry(this.name(), line);
  feat.maxzoom(6);
} else {
  feat = features.line(this.name());
  feat.minzoom(7);
}

[adjourn]

I could be missing something here but this doesn't work out, already tried that.

Because if block will replace geometry for the given feature and it does so for all zoom levels. If I then limit it to max zoom 6, it just means that zoom 6+ won't show any geometry for given feature.

So the goal for singular feature:

• For zoom 6, show my custom simplified geometry
• For any other zoom (6+ in this case), show OSM geometry

[wipfli]

// in source handler
if (sourceFeature.getTag("name").toString().equals("Some Major River")) {
  var line = Utils.createLineString(new double[] { /* ... */ };  // <- uses GeoUtils.JTS_FACTORY.createLineString
  var feat = features.geometry(this.name(), line);
  feat.maxzoom(6);
  var feat2 = features.line(this.name());
  feat2.minzoom(7);
} else {
  var feat = features.line(this.name());
}

[adjourn]

Oh.. I think it finally clicked for me how collector works. Duh!

So there is no hidden low level API to create features without relation to OSM data, you just create them, either with the help of OSM source data or not! Now I feel stupid for not realising it, had very wrong image in my head. 🙃

[adjourn]

Thanks for taking your time to help me!