3D Tiles demo has terrible imagery performance

[mramato]

In my machine, loading the 3D Tiles example in IE 11 and without ever moving the camera, it takes over a minute for all of the imagery to come in. If I use the same default view (below code snippet) but without 3D Tiles loaded, it only takes a couple of seconds. I'm not sure if this is a problem with the new request scheduler or something unrelated. I actually see a similar issue in Chrome but it's much faster (several seconds vs instant rather than a minute vs a few seconds).

var viewer = new Cesium.Viewer('cesiumContainer');
viewer.camera.viewBoundingSphere({"center":{"x":1215020.301129722,"y":-4736341.9686844405,"z":4081630.311150717},"radius":200.90026973524507}, new Cesium.HeadingPitchRange(0, -2.0, 0));
viewer.camera.lookAtTransform(Cesium.Matrix4.IDENTITY);

[lilleyse]

One thing to try is turning RequestScheduler.prioritize to false or RequestScheduler.throttle to false.

[pjcozzi]

Even in Chrome, compare these:

• 1.24: http://cesiumjs.org/releases/1.24/Apps/Sandcastle/index.html?src=Terrain.html&label=Showcases
• request-scheduler-master: http://localhost:8080/Apps/Sandcastle/index.html?src=Terrain.html&label=Showcases

If you, for example, quick and dirty select the "Half Dome" view, it is clear that it loads faster in 1.24. Perhaps this is as simple as default parameters being too conservative? Or are we not making as many requests as we think we are....or the wrong ones?

We need to address this before merging #3476.

[lilleyse]

Maybe it's just my computer, but I'm running both branches locally and the results are about equal on Chrome and IE. Do you notice it working better when RequestScheduler.prioritize is false?

[lilleyse]

Either way I will look more into this.

[mramato]

Either way I will look more into this.

I would definitely make sure you start with a clean cache while working on this; it will exaggerate the problem since latency of requests is probably a big factor here.

[pjcozzi]

Clean cache or just use dev tools to throttle the speed.

The cache was warm and still noticeable for me.

[mramato]

Turns out this is also a problem in master too and is directly related to fog being disabled and has nothing to do with 3D Tiles.

I guess the bigger question is by is disabling fog producing such poor performance for a straight down close up view?

[mramato]

Add viewer.scene.fog.enabled = false; to my "working" example in the original post and you can see htis for yourself.

[pjcozzi]

@bagnell can you please look at this when you have time? Ideally before 1.25 next Thursday.

[pjcozzi]

Perhaps now duplicate with #4359.

[mramato]

I doubt it's a duplicate, since shutting off fog is what causes the behavior in this issue and turning it back on fixes it.