Not displaying GroundOverlay in KML file.

[dwhipps]

This is likely a two-part ticket, but for starters, the KML file I have here:

https://earthdata.layeredearth.com/Layers/Earth/Climate%20Change/Other/Malaria%20in%20Africa%20Projections.kmz
... does not display anything in Cesium, seen in SANDCASTLE here:

http://cesiumjs.org/Cesium/Apps/Sandcastle/?src=Hello%20World.html&label=Showcases&gist=a2c8d3fa055a3a341114040331265ac7

I suspect this has to do with the nested elements in the kml, but I can see that processGroundOverlay is getting called, they're just not being displayed.

(The second part of this, which I'll put in a separate ticket, is that Cesium shouldn't be processing feature nodes unless they're 'visible' as defined here: https://developers.google.com/kml/documentation/kmlreference#folder)

A Folder is used to arrange other Features hierarchically (Folders, Placemarks, NetworkLinks, or Overlays). A Feature is visible only if it and all its ancestors are visible.

[hpinkos]

Thanks @dwhipps!
I think the issue might be related to a bug we've seen with timespans: #4041

For visibility, from looking at the code it looks like that is being processed correctly. When is sees visibility of zero, it sets show to false. I think we still want to process it in case a user wants to set show to true later on.

[dwhipps]

It's not clear on whether this has a decent chance of getting fixed. It's a bit of a show-stopper, as nothing at all renders.

[hpinkos]

Sorry, I can't promise that we'll be able to get to it immediately.
We are planning to spend a few days in October tackling frequently requested bug fixes. This seems like it might be a good issue for us to look into then since it is effecting multiple users.

[mramato]

@dwhipps thanks for the report. If you're up for it, there's no need to "wait for us" to do something, Cesium is a community with lots of contributors and we are more than happy to take a pull request for this or any other issue. This sounds like something that would be isolated to code in KmlDataSource.js

[dwhipps]

After further investigation, this appears to be a case of Google Earth (and WolrdWind) being more lenient than Cesium. There were multiple GroundOverlay nodes with the same node "id" (these should be unique), so when getOrCreateEntity is called inside processFeature, the existing entities were being found with that id, no new entity was created, and entity.show was being set to false (because the last instance was not 'visible'.)

I confirmed this by simply changing the duplicated node ids. All was fine after that.

In short, I don't think this is actually a bug in Cesium. Not sure if there's a way to warn if multiple nodes are found with the same ID, but seems like a real edge-case.

I'm closing this issue.