Optimize the scene in big city models

[ValerioBozzo]

Hi all,

I started working in CityEngine about 6 months ago for my graduation thesis. I must create the city model of my town, Cosenza (Italy) using gis data. I created a big city model (the total surface is about 623.74 square kilometers). I created the terrain with a tiff image (heightmap), and the resolution is 4096x4096. The streets are imported from open street map and the buildings footprints are imported from shapefiles.

When I try to execute simple operations with the streets and the model I have to wait a lot of time before CE finish the operation. It is very frustrating an time-wasting. My computer is not so bad (My Computer is an MSI GT70 Dominator pro, with 32gb ddr3 1866mhz of ram, nvidia gtx880m graphic card with 8gb of dedicated memory, and intel i7 4930mx 3.2 ghz cpu).

How can I optimize my scene? Any suggestions?

[MatthiasBuehler]

Hi Valerio,

You only have 368'000 polygons, that's not a lot.

First of all, when working in CityEngine, I NEVER generate all models unless I need it for screenshots. If you're creating code or editing the network, you don't need the generated models. This saves HUGE amounts of resources.

The second thing: Try to optimize the terrain's subdivision (check docs!), this usually is a lot of polygons by default.

Third, make sure you deactivate shadows and ambient occlusion to make the viewport display your data quicker.

Let me know if this helps.

Cheers!

m.

Matthias Buehler

Head of 3D Technologies

twitter: @MattB3D

-------------------------------------

Garsdale Design Limited

matthias.buehler@garsdaledesign.co.uk

www.garsdaledesign.co.uk

[ValerioBozzo]

Hi Matthias,

thank you for quick response and support. Do you think working with many layers (deactivating when not needed) will make the scene faster? I tried splitting the streets in 6 different layers, but apparently it doesn't work.

The terrain is very big, but I don't know how to split in small pieces. The subdivision is 4096x4096, but I can't reduce it because I need an hi-def terrain in the zone near the river (When I finish my city model I need to export it for animations about flooding and the surfaces in contact with the water should be as real as possible, indeed I aligned the terrain to a laser scanning in the river area).

Sure, when I work in CE i deactivate ambient occlusion, shadows and if I don't need it even the textures.

Thanks for your time

[MatthiasBuehler · Accepted solution]

Hi,

Well, 4k x 4k subdivisions results in a 16 million poly terrain. total overkill.

CityEngine does have a limitation in the terrain functionality and does not have adaptive subdivision for terrains implemented or TINs (a specific precise terrain triangulation).

I can only recommend to reduce the terrain subdivision in this case - even if you're losing some of the detail. At least for the time when you're working / editing the scene.

Matt

Matthias Buehler

Head of 3D Technologies

twitter: @MattB3D

------------------------------------

Garsdale Design Limited

matthias.buehler@garsdaledesign.co.uk

www.garsdaledesign.co.uk

[ValerioBozzo]

Once again, you were right. I turned down the resolution and the scene is more fluid and reactive when I work on it.

What if I hide some layers? Does it impact to the scene fluidity? I noticed that if I hide some layers, it doesn't affect the fluidity. Is it true?

Regards,

Valerio