GeoJSONOverlay: Possible improvements

[gkjohnson]

Features

• Add support for a form of "styling" the GeoJSON.
• Add support for multiple GeoJSON shapes (array of URLs, shapes).
• Add support for regenerating images based on color / shape / styling changes.
• Add support for raycasting / sampling geojson coordinate based on mouse position / or latlon value.

Quality

• Handle GeoJSON shapes across the +-180 degree longitude boundary.
• Add padding based on pixel size, stroke size, and point size to ensure shapes are included in bounding box calculations to prevent shape clipping.
• Add support for world space sizing so line width etc does not scale based on zoom / pixel size.
• Consider scaling canvas dimensions based on ellipsoid-projected size to retain roughly square pixels, prevent distortion.
• Image Overlays: Allow for "dynamic" depth and loaded tile size #1310

Memory

• Add support for limiting the bounds in which images are produced to only where shapes are present. Fixed in TilingScheme: Fix incorrect reporting of empty tile ranges #1328.
• Add support for only loading tiles where geojson shapes are present including between geojson shapes.

Performance

• See if converting to SVG is performant.
• Use web workers and offscreen canvas.

[Ylannl]

Very nice to see this effort!

What do you think about a picking feature? This would be very useful, ie. to query attributes, and for the ability to 'select' features (which would then be reflected with a color/styling change of those features).

As a reference, there is some sort of picking feature for draped vectors in Giro3D.

[gkjohnson]

What do you think about a picking feature? This would be very useful, ie. to query attributes, and for the ability to 'select' features (which would then be reflected with a color/styling change of those features).

Raycasting seems like a good feature to support. I have expected this to be implemented as a separate utility in an end-user application but maybe it makes sense to include support in the plugin. The most simple way to do this is provide a function that takes a latitude and longitude value (or tile-space value to transform into the relevant projection) and perform polygon intersection checks with the geojson shapes.

Figuring out how to efficiently support dynamically colored shapes with a tiled system like this would still take some thinking, though.

As a reference, there is some sort of picking feature for draped vectors in Giro3D.

It looks like Giro3D doesn't support recoloring of the shapes, is that right?

[Ylannl]

Ofcourse, implementing this in an end-user application is also a viable option (except for the recoloring perhaps). I can imagine you want to keep this library mostly focused on 3D data/rendering, but this geojson work got me thinking.

It looks like Giro3D doesn't support recoloring of the shapes, is that right?

There are examples with recoloring.