Invalid Web Scene (3ws) data

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10-18-2013 07:56 AM
JeffShih
New Contributor III
Good morning all,

I'm having an issue exporting a particular scene. It contains a terrain with a DSM derived from a point cloud and image captured by a drone. I have never seen this error before and have tried googling the exact phrase, but nothing shows up.

Here's a screenshot of the error log I receive upon attempting to open the webscene locally from within CE. The error just keeps repeating off the page. Any insight would be greatly appreciated.
[ATTACH=CONFIG]28442[/ATTACH]
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4 Replies
AndreasUlmer
Occasional Contributor
hi

hard to say what the problem is from the distance. We'd need the 3ws file to track the problem down. Is it possible for you to share it somehow? If you don't want to share it publicly, please PM me.

Andreas
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AndreasUlmer
Occasional Contributor
Hi Jeff

thanks for the file. I looked into it and found invalid values in the 3ws (infinity values and huge coordinates), which cause the parser to break.

(FYI: a 3ws is just a gzipped json file that's human readable. You can unzip a 3ws to look into it, modify and rezip it if desired. Make sure to use gzip as archive format. 7-zip works fine for this).

I tried to track down where these invalid values come from. So far it seems to be a bug in the CityEngine coordinate conversion happening during 3ws export. I still need to investigate further, but it might be that it is related to that specific spatial reference you are using.

As a possible woraround, can you try to prepare the raster in a different projection, and recreate the CityEngine scene with that new projection? e.g. UTM zone of Canada.

For further investigation:
* in what area is the raster data located? what size/extent does it span?
* can you share the raster file (or a smaller extent) so we can better reproduce the problem?


thanks
Andreas
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AndreasUlmer
Occasional Contributor
Hi Jeff

thanks for the additional files, great help to reproduce the issue.
I don't have a full explanation yet, but hopefully a workaround for you.

0. from the data you provided
1. open the (empty) cej.
2. import the raster
3. select terrain layer, fire up the 3ws exporter, open the Misc options tab:
in the global offset field, I see the infinity values (see img)
4. get rid of those by clicking center. this will reevaluate the offset coordinates correctly
5. export -> 3ws loads fine


###

I did encounter a follow up issue however on the resulting web scene: when I export the terrain on its own, I see strange holes in the resulting Web Scene. I could avoid this by adding a single shape that I manually created below the terrain (just roughly in that area). When exporting the terrain with the shape in the scene, the exported terrain looks fine (even if the shape is not included in the web scene).
It looks like there is some flaw in calculating the bounding box of this terrain, causing a) the inf offset error and b) incorrectly merged (dropped) faces on export due to precision issues originating from this incorrect bounding box.






and some good news:
I tested the same thing in soon-to-be-released CityEngine 2013, and it works fine with none of the above issues.

best
Andreas
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JeffShih
New Contributor III
The problem has been resolved. Thank you so much Andreas.
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