importing models from CityEngine to ArcGIS webviewer

Question

Hi there.
I have got shape files (houses) in 3D which were made with the Stereo Analyst extension in Arcmap (works with Leica photogrammetry suite).  When I import them into CityEngine everything is alright. But when I export them as a cityengine webscene and upload them into my content on ArcGIS online they show up with some of the walls or roofs transparent or missing.  
I'm attaching pictures fro the CityEngine viewer and the ArcGIS online web viewer to show the problem.
I'm pretty new to City Engine so this is hopefully something very simple.

Hope fore a quick answer.

Best regards
Thorvaldur E. Saemundsen

arcgis_online_webviewer.JPG

cityengine_viewer.jpg

ALANDIA40_0-1745521366276.png

021-Hachey-Boudreau-Mariette-.jpg

Thorvas72 · Answer

Hi there Matt.

Thank you for the quick reply.  I got to the same conclusion but didn't know how to fix it.  Since we created the data we can only blame our self but I don't think we can control the normal so it all faces out.  It will be to time consuming to change all the polygons manually so I hope this CGA rule will help me :) .

Thanks alot.

Best regards
Thorvaldur

Anonymous User · Answer

Original User: matthiasbuehler

Hail the mighty Thorvaldur !

[sounds like a mighty Viking warrior king :o ],

Those polygons are not missing. WebScenes are just displaying all polygons single-sidedly. The polygon's normal defines what is the 'front' of the face. Only the front is rendered, basically to render everything faster.

Means you'd have to reverse the normals of those polygons before exporting to see them. Now this is a manual process to clean that stuff up precisely.

2 options :
1] ask the data provider if they can produce the data with proper normals ( all normals pointing 'out' ). Though I assume that's mathematically almost impossible
2] a quick & dirty fix in CGA which just duplicates each polygon and reverses the normal :
Shape -->
    comp(f) {all : Shape1. reverseNormals Shape2.}

I assume you know how to assign this rule before exporting to a WebScene.

Lemme know if this all makes sense.

Matt