ArcGIS TiledElevation Terrain Provider

[Tamrat-B]

Added support for LERC encoded terrain from an ArcGIS ImageServer (Tiled Elevation services) as 'ArcGISTiledElevationTerrainProvider'

[cesium-concierge]

Thanks for the pull request @Tamrat-B!

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[pjcozzi]

Really fantastic, thanks @Tamrat-B and @chri7928!

I just added you to our automated CLA system.

[tfili]

Thanks a lot @Tamrat-B @chri7928. This looks great.

[robbo1975]

@Tamrat-B @chri7928 Is this provider intended to be able to be used with part-world ESRI terrain services? I am not having much success getting it to work with a custom part-world ESRI AWS service. The service does not expose the 'Tilemap' capability, but when 'bypassed' the data returned is [0,1,0,0] (instead of [1,1,1,1] which is exposed by the public terrain service), this causes the provider to 'lock-up' when trying to execute 'findRange()'. I am unsure if this is a bug in the provider or if there is an issue with the way in which the service is set up. Any advice would be appreciated.

[OmarShehata]

@robbo1975 I'm not sure what the answer is, but I'd recommend making a new topic on the community forum (https://community.cesium.com/) and add some instructions about how to reproduce (and any relevant links in the ESRI docs) to help us and others in the community investigate.

[Tamrat-B]

@robbo1975 @OmarShehata
This use case is supported in the provider. During the development we verified with this use case and it did work. @tfili has confirmed nothing has changed in the provider; So most likely it might be how the service is set up; Can you pls provide an example of the service to @tfili for debugging if possible. thanks

[robbo1975]

@Tamrat-B @OmarShehata @tfili Thank you so much for responding to my query. Unfortunately I am not able to share the actual service as it is a private service set up by ESRI UK in an AWS environment. I am able to provide some details of the nature of the problem and snippets from the JSON etc. Would you prefer for me to open a thread on the community to provide the details or to paste them here? I have a whole range of diagnostic information ready to share as there appears to be several issues that cause the plugin to fail.

The service:
"currentVersion": 10.71
"capabilities": "Image,Tilemap,Metadata,Mensuration" (note, I previously reported that TileMap was not returned, but ESRI UK fixed this)

Summary of main issues found:

1. The findRange() function in the provider gets stuck in an infinite loop very early on from the TileMap json data that is returned from /tilemap/1/0/0/2/2 [0,1,0,0]. The function is called with:
   findRange(origin = Cartesian2 {x: 1, y: 2}, width = 2, height = 2, data = (4) [0, 1, 0, 0])

2. If I bypass the findRange() function no further tiles are attempted to be downloaded because the GlobeSurfaceTileProvider.prototype.computeTileVisibility returns visibility.NONE as a consequence of HeightmapTessellator.computeVertices setting the minimumHeight to -1x10^38. The reason that this happens is that it appears after LERC decoding the tile returns this extremely large negative number (presumably for areas where no data is provided). If I hack the code to return a mimiumHeight=0 when this happens then the globe will appear and the tiles are downloaded, but the terrain does not look correct and it is extremely slow whilst trying to get hold of tiles that do not exist (404 errors on console)

Any assistance you can provide would be appreciated as I am not a Cesium, ESRI or mapping expert!
Robbo

[OmarShehata]

Would you prefer for me to open a thread on the community to provide the details or to paste them here? I have a whole range of diagnostic information ready to share as there appears to be several issues that cause the plugin to fail.

I think it would be helpful to move this discussion to the forum, that way anyone else running into it can contribute as well, and once we determine whether it's a CesiumJS bug, something that isn't supported, or an issue on the data side, we can open a new GitHub issue here that outlines what needs to be done.

I understand the service causing this issue is private, but if you can reproduce this with a terrain provider of the same type that's publicly available that'd help a lot (perhaps there's some sample data ESRI terrain data that can be used?)

[robbo1975]

@OmarShehata @Tamrat-B @tfili For completeness, I have raised the following topic on the community forums: https://community.cesium.com/t/does-esri-terrain-provider-support-part-world-terrain-data-services/10382

[Lauxb]

@Tamrat-B @OmarShehata @tfili I encountered the same problem and couldn't find the answer after browsing through the forum. Therefore, I published a public test service to recreate the issue for testing. I hope to receive responses from everyone. I would be very grateful.