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How to remove elevation from BIM file?

  • January 29, 2021
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oscard
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Good morning.

 

I'm putting together a workspace to transform a Revit file into Cesium 3D tiles. Overall, it is a pretty straightforward process, but I'm facing an issue with the elevation.

 

The building stored in the Cesium 3D tiles is floating, so I need to offset the Z to put it in floor level over a 2D basemap. I've been using the Offsetter transformer with lots of trial and errors until getting it right, but I would like to know if there is a better way.

 

So the question is: Is it possible with FME to make that "elevation removal" automatic?

Best answer by chrisatsafe

Hi @oscard​ ,

If you have floating features you can use an ElevationExtractor (1 in the image)or BoundsExtractor (2 in the image) to get the z value, then set the Offset Z value to negative @Value(_elevation) or @Value(_zmin). This extract the elevation to an attribute (either _elevation or _zmin depending on the transformer you use) which can then be used to offset in the Offsetter. 2021-02-02_14-13-54

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2 replies

chrisatsafe
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  • chrisatsafeContributor
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  • February 2, 2021

Hi @oscard​ ,

If you have floating features you can use an ElevationExtractor (1 in the image)or BoundsExtractor (2 in the image) to get the z value, then set the Offset Z value to negative @Value(_elevation) or @Value(_zmin). This extract the elevation to an attribute (either _elevation or _zmin depending on the transformer you use) which can then be used to offset in the Offsetter. 2021-02-02_14-13-54

ferhdfme
oscard
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  • oscardInfluencer
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  • February 3, 2021

Hi @oscard​ ,

If you have floating features you can use an ElevationExtractor (1 in the image)or BoundsExtractor (2 in the image) to get the z value, then set the Offset Z value to negative @Value(_elevation) or @Value(_zmin). This extract the elevation to an attribute (either _elevation or _zmin depending on the transformer you use) which can then be used to offset in the Offsetter. 2021-02-02_14-13-54

Hi! Thanks for the answer!

That worked.

 

I have to aggregate the geometries first and then apply the ElevationExtractor, otherwise all the buildings floors are pushed to the ground.

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