Improve loading efficiency for Tileset

mycleaerlife · November 17, 2023, 8:05am

Hi , Cesium Team，with my thought ,there are some good ways to Improve loading efficiency for Tilesets, and For me, a lot of experimentation has been done in Unreal Engine, When my Camera close to Data, that load Depth Tile very Slow( speed 5 ~ 10 scend ).
And I Debug Cesium-Native Code, I Found its only one scheduling scheme for Terrain And Tileset which is quadtreeLoader( I am sorry ,I am not very similar for Cesium-Native Code, And I Speed less Time on it ). SO, is there any Solutions or suggestions for Construct My Tileset Data For QuadTreeLoader Scheduling. Can I Use My Traversal for Loaded Tiles And SkipLevel for it , Maybe it needs Stencil Test For Depth, I dont know that ,Can you Give some advice on that

Kevin_Ring · November 20, 2023, 2:14am

We have a recent PR that drastically improves load performance in Unreal:

github.com/CesiumGS/cesium-unreal

Improve network performance by fixing libcurl thread

CesiumGS:ue5-main ← CesiumGS:fix-network-throttling

opened 06:07PM - 16 Nov 23 UTC

csciguy8

+6 -0

Decrease the value of `HttpThreadActiveFrameTimeInSeconds`, from 0.005 to 0.001.… This controls how often Unreal Engine polls libcurl. Now we do it more often. Overall, all test locales seem to benefit. In the most demanding tests (Google Tiles), load times are **~2.5x faster.** Previously, a user who viewed the NYC Chrysler building would wait ~14 seconds for it to load. Now it only takes 6 seconds. Tested these things: * 4 different performance tests, see below - All passed, and are faster * Flying around Unreal editor with Google Tiles - Good framerate and responsiveness * Flying around a packaged game - Good framerate and responsiveness * Unreal Insights - Everything looked like before, except the events were more tightly packed (which is expected) Performance Tests Summary (cold cache) ----------------------------------------- ``` SampleLocaleDenver - 13% load time reduction SampleLocaleMelbourne - 16% load time reduction GoogleTiles.LocaleDeathValley - 61% load time reduction GoogleTiles.LocaleChrysler - 57% load time reduction ``` Complete Testing Data ----------------------------------------- ``` HttpThreadActiveFrameTimeInSeconds set to 0.005 (existing default) -------------------------------------------------------------------------- SampleLocaleDenver (27 MB) Cold cache - 3.32, 3.03, 2.94 - 3.09 avg Warm cache - 0.71, 0.79, 0.75 - 0.75 avg SampleLocaleMelbourne (89 MB) Cold cache - 4.68, 4.19, 4.24 - 4.37 avg Warm cache - 1.16, 1.15, 1.14 - 1.15 avg GoogleTiles.LocaleDeathValley (27 MB) Cold cache - 9.95, 10.02, 10.20 - 10.05 avg Warm cache - 1.37, 1.33, 1.41 - 1.37 avg GoogleTiles.LocaleChrysler (55 MB) Cold cache - 13.89, 15.32, 14.38 - 14.53 avg Warm cache - 2.28, 2.28, 2.34 - 2.30 avg HttpThreadActiveFrameTimeInSeconds set to 0.001 -------------------------------------------------------------------------- SampleLocaleDenver (27 MB) Cold cache - 2.78, 2.68, 2.62 - 2.69 avg Warm cache - 0.68, 0.71, 0.79 - 0.72 avg SampleLocaleMelbourne (89 MB) Cold cache - 4.07, 3.48, 3.45 - 3.66 avg Warm cache - 1.20, 1.17, 1.18 - 1.18 avg GoogleTiles.LocaleDeathValley (27 MB) Cold cache - 3.98, 3.77, 3.88 - 3.87 avg Warm cache - 1.32, 1.32, 1.33 - 1.32 avg GoogleTiles.LocaleChrysler (55 MB) Cold cache - 6.29, 6.17, 6.13 - 6.19 avg Warm cache - 2.27, 2.24, 2.31 - 2.27 avg ```

Beyond that, you’ll need to describe more carefully what you’re looking to accomplish. Cesium for Unreal is open source, so you can make whatever modifications to it you like. But we can’t give you specific answers without more specific questions.

mycleaerlife · November 20, 2023, 6:26am

HI @Kevin_Ring, I’m very appreciate for your reply, I’m sorry that my ideas are not very mature, and that PR is very useful for my test now. I want to access the deepest level tiles faster and have smaller memory，so I want to use this “Skipping Levels of Detail – Cesium”, And I don’t know Moving CesiumJS traversal to CesiumNative … Is it reasonable? I have already finished some of works for that in my local, If you give some advice on that, I’ll be very happy.

Kevin_Ring · November 20, 2023, 6:53am

cesium-native already implements a level-skipping technique that is more performant than the one described in that blog post. It can sometimes lead to holes in the surface with certain camera movements, and that’s a problem for some applications, but you’re unlikely to get better performance with the CesiumJS technique (and it has its own artifacts caused by the imperfect stencil test).

In cesium-native, to minimize the loading of intermediate tiles in the pyramid, set the “Loading Descendent Limit” property to a large number, such as 9999. To minimize the number of tiles loaded in total, turn off the two “Preload” settings.

Brian_Langevin · November 20, 2023, 5:06pm

Do you think you can give us more details of your use case?

What is the map data you are using?
Are you using Cesium Ion assets or Google P3D Tiles?
What lat / long are you viewing from?
What is your network bandwidth?
What platform are you on? Windows? Linux? etc.