Cesium offset position back to the iTwin/3DFT position

[MortonPriceBBV]

Team, I need a way to offset my iTwin models to their original 3dft position.
The current Cesium conversion offsets/rotates, which then no longer coordinates with other data sets imported into UE5

[GhisBntly]

Hi Morton,
You can edit the AITwinIModel actor's transform in Unreal Editor's Outliner and it will be applied on top of Cesium's georeferencing.
But you probably already knew that: do you mean you need a way to compute the exact values to use for offset and rotation?

If the iModel is geolocated, then your other datasets need to be geolocated too, and cesium locates them correctly with respect to each other.

If the iModel is not geolocated, cesium will place the zero of the Unreal world at the center of the iModel's project extent (to optimize coordinates precision), not at the origin of the iModel spatial coordinates.
I think the old 3DFT plugin did things differently for the placement (as for rotation, I'm not aware of any difference between 3DFT and Cesium tilesets), but I'm not sure exactly what.
You can filter the Unreal Editor logs with "iModel project extents" to get the extents in iModel coordinates, for example:
LogITwin: Display: iModel project extents: min=X=-788.677 Y=-536.020 Z=-25.360, max=X=779.700 Y=1244.513 Z=96.972, centered on X=-4.489 Y=354.246 Z=35.806
You can maybe try offsetting the iModel actor by the "center" value, converted into Unreal world coordinates by multiplying the vector by (100, -100, 100) (ie. Y axis inverted!), in my example it would be X=-448.9 Y=-35424.6 Z=3580.6

Hope this helps,

[danielwikstrombentley]

Hi Ghislain, the issue Morton is having is that manually moving around the tilesets back to where they were showing up with the 3dft plugin. He has tons of content that was placed to match the 3dft tilesets, and moving around his more than 30 imodels is impossible (He has tried, and just getting one model to line up perfectly is impossible as they are long linear assets). The solution would be to have a toggle (perhaps in the config file) to place the assets in the exact same location as where they were appearing with the 3dft plugin.

[GhisBntly]

For the record, there is a geolocation bug in version 0.1.15 of the plugin that I had forgotten about when writing my previous comment - see the reply just posted to #39