Trouble with misalignment when converting ESPG 27700 2D map to a 3978 3D model for Unreal Engine

​@dlhartleryan 

My advise: ChatGPT is always not correct atleast when it comes to FME workflows suggestions.

That is why we have this large FME Community.

Welcome to the FME Community!

Most of this all works perfectly fine and expected (this is a great piece of software!) but the result has the reprojected map not perfectly flat on ground and facing the wrong direction

Your workflow shows a Reprojector followed by CsmapReprojector.

Can you tell us more about the settings in it? and what made you use two reprojectors in series?

SRG

Hi Reghavendrans, thanks for commenting.

Originally I only used the CsmapReprojector from 27700 to 3978 and this gives the same result as shown in the original graph. I only tried two reporjections out of desperation.

The settings that I have in CsmapReprojector are attached

​@dlhartleryan 

A wild guess is that the issue of incorrect output could be due to mix up of data in different coordinate systems somewhere in the workflow.

Let me get it correct!

You stated that you are adding height data from a PointCloud which according to you is in EPSG 4326 to EPSG 4978

You have also stated that you are converting 2D mapping data which is in EPSG 27700 into a 3D Object in EPSG 3978.

May I suggest that you double check that before different types of data get routed into any transformer in your FME Workflow, they are all in the same coordinate system?

Happy FME:-) ing

Cheers

SRG

No the point cloud data is in 27700 and so is the original map. The Height map is applied and then the 3D map data is reprojected into 3978.

Whether it is reporjected into 4326 first or not has no effect on the outcome.

I have inspected all the data at every point and everything is correct to my eyes.

I think the problem lies with Unreal Engine and Cesium doing a separate translation involving axis arrangement and rotation so that the map appears flat.