Use case: Technical drawings (panning, zooming, layers, etc.)

[prushforth]

This issue is for discussion of the use case “Display drawings or schematics without geographic coordinates”, its examples & list of required capabilities.

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Per discussions with @satakagi at TPAC, an important level of progressive enhancement of the <map> element could be "deep zooming" of non-georeferenced technical drawings, such as schematics of microprocessors etc.

Recently the "WGS84" projection in MapML was extended to support tile resolutions at different zoom levels. Is this projection adequate for this use case?

[AmeliaBR]

Based on the strategy in the new report, there are two ways of thinking about this use case:

• Panning & zooming are low-level capabilities that could be implemented in CSS/HTML separate from a map viewer, so they can be reused for other types of content.

• Within the map viewer, a potential capability is the ability to draw and layer graphics that use non-geographic coordinate systems.

I think that both have benefits. For something like "zoom in on a product photo", you maybe don't want all the extra UI and complexity of a map viewer. But for complex technical drawings or architectural blueprints, you may want more than just panning & zooming, you want layers & markers with pop-ups & lots of the other capabilities from the map viewer — everything except connecting the drawing to specific latitude and longitude.

[prushforth]

As chance would have it, there is some discussion of incubating infinite scrolling recently on WICG. Somebody did note in a GitHub issue for that project that 2D stuff including map tiles is of interest, not just text. It doesn't look like the authors of virtual-scroller took that suggestion to heart yet, though.

[prushforth]

Twitter never disappoints. There is a standard API for non-georeferenced imagery, with a number of viewers , which perhaps use the API.

[AmeliaBR]

Here's a lovely example of using GIS software for non-geographic data: https://twitter.com/pokateo_/status/1186620601949134849

[prushforth]

I just noticed that the examples for Leaflet and OpenLayers use the TMS convention of tile matrix origin at the lower left position and the y axis positive upwards; this is conveyed to them through the use of the {-y} url template variable. I view the whole token to be a template variable reference, and as with other URL template variables in Leaflet, it 'understands' the meaning of the variable by its name '-y', which embeds the client-server coupling that we must avoid.

So, either we have to include support for TMS, taking it into account in these UCRs (we probably could define a TCRS this way, but not sure it's a good idea for an obsolete and niche spec such as TMS), or potentially migrate our examples towards origin-at-top-left examples.