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Question

Incorrect scale of FBX model converted from CityGML model

  • January 20, 2025
  • 2 replies
  • 31 views

cossy27
Contributor
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Hello! I am currently trying to convert the CityGML models into FBX format using the workflow below.

However, it was found that the absolute position of the FBX generated would be 100 times less than the original model. Therefore, I added a Scalar transformer in my workflow. There isn’t any problem in display but the relative dimension value would be multiply by 100 as well. The enlarged dimension could not be visually observed even being compared with other normal objects but the dimension value would be 100 times larger. (Not sure if I am describing the issue clear enough)

Moreover, I also found that the Aggregator transformer at the end was not actually grouping the surfaces as one surface. They were just grouped under an object where this object was not a geometry. I tried the Surface Dissolver to merge the surfaces but in vain. If I don’t group the surfaces together, they will be exported as a series of Surface Member which would be difficult to manage during viewing.

Therefore, I attached my workflow below to seek your comments on it and grateful if you could explain the reason for the scaling issue in conversion from CityGML to FBX.

Thank you!

 

 

2 replies

virtualcitymatt
Celebrity
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instead of the Aggregator you should instead convert the Geometries into mesh geometries and then use the MeshMerger.

There are a couple of way to convert your geometries into meshes. 

My preferred method is to use the Triangulator - The TINSurface output of the transformer will be mesh geometries. You can then feed the features from the TINSurface output into a MeshMerger. This will output a single triangulated mesh which you can then output to FBX.

The most likely issue with FBX scaling is that FBX is usually in cm and FME is in meters - so when you write out FBX, FME may not be scaling the model as expected. The FBX reader in FME has a parameter to convert models into meters, however there isn’t one on the writer. 

I think scaling by 100 is appropriate if the result works for you. 
 


cossy27
Contributor
Forum|alt.badge.img+2
  • Author
  • Contributor
  • January 20, 2025

Thank you Matt!


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