Bentley mesh import issue: not referenced

[densecloud]

Hi!
I've imported a OBJ mesh generated from Bentley ContextCature in RGF93 / CC48 (EPSG:3948).

The OBJ mesh is well visible on Metashape but only in Local coordinates (option is greyed at import, no other SCR choice possible). The goal is to perform measurements and orthofacades.

Bentley generates a reference metadata.xml (attached) file, not supported by Metashape.

Any clue ? 

[Paulo]

Hello Densecloud,

I have a guess that maybe the Origin entry from XML:

Code: [Select]

<SRSOrigin>557357,5260546,0<correspond to shift you must apply during Object import into Metashape, as in following:

PS. from Origin coordinates it seems your model is a Communications tower en Bretagne....

[densecloud]

Hi Paulo!

Thanks for your reply. I'm still stuck at import window, no SCR can be selected although exported from Bentley (EPSG::32630)

[Paulo]

Bonjour dense cloud,

yes it seems that when importing to an empty project you need to simulate a chunk transform using a work around by entering following line in Console pane:

Code: [Select]

Metashape.app.document.chunk.transform.matrix = Metashape.app.document.chunk.transform.matrix
you then can import specifying correct CRS and offset:

Exemple de modele de une eglise imported with correct CRS 32630 et shift parameters... it falls on top of com tower....

[densecloud]

Well done! 

Now I have to figure out why my model looks like "splats"...

The model with black background is Bentley's.

Merci beaucoup !

Olivier

[Paulo]

Olivier,

cela semble un probléme de texture...le modèle a-t-il le meme nombre de faces que l'original?

Au fait, 47 m es ce la hauteur mesurée de la tour? Car à partir de l'ombre projétée sur GoogleEarth, j'obtiens une hauteur d'environ 33.5 m....

[densecloud]

La plateforme est à environ 43m et l'ensemble fait 47m.

L'import du .obj en Local coordinates est pourtant parfait, en chunk transform je n'ai que 150k faces ce qui ne colle pas.

Peu de souplesse avec Bentley comme Pix4Dmapper...

Je vais jeter un oeil à l'API Python s'il n'y a pas un paramètre...

En tout cas merci !

[Paulo]

Le mieux serait d'avoir un vrai projet avec photos sur la zone d'intérèt car la simulation avec chunk.transform déforme le modèle....

Voir avec agisoft aupport si possible...

PS. in fact this issue could be solved developping a script that would read the Bentley Metadata file and correctly georeference the model without introducing distorsion....  as in following attachment where I imported a 3dmodel in Local CS (left side) and then used the Bentley Metadata to georeference the model (ight) with no distorsion). In this case Bentley Metadata contains:

<?xml version="1.0" encoding="utf-8"?>
<ModelMetadata version="1">
   <!--Spatial Reference System-->
   <SRS>EPSG:2157</SRS>
   <!--Origin in Spatial Reference System-->
   <SRSOrigin>716975,734277,58</SRSOrigin>
   <Texture>
      <ColorSource>Visible</ColorSource>
   </Texture>
</ModelMetadata>

so SRS is Irenet95 / Irish Transverse Mercator and the SRSOrigin points to some place in Dublin....

[densecloud]

Thanks!

I keep in mind that, anyway my client finally opts for Bentley Descartes...