Silly impostor issue

[brentskegg]

Hi!

I'm trying out some tree impostors for my trees (clutter) with a fairly long visibility distance, 20 km. The problem is that the impostors fades away long before that, like already at 4-5 km. And its not a bug in unigine I think, the cause is that the impostors gets smaller than a pixel at that distance and "disappear". Its obvious if you are changing the fov (zooming in/out), looks like the impostor visibility distance is changing but its just the impostors getting smaller or bigger than one pixel.. Anyway, what would be a good solution for that? 

The only thing I've come up with is to do another lod mesh, consisting of just one billboarded plain triangle (without any alpha testing/texture). And then somehow making that lod appear at the appropriate time when the tree impostor gets less than one pixel (in width I guess). The idea is that without the alpha test the triangle will atleast show as a pixel or two, which would be sufficient as a tree at that distance. Not sure if can do that at the impostor node, will probably have to be on its parent clutter node, which would mean I also would need a 20 km visibility distance for the clutter node.. And I guess thats a bad thing to do.

Well, maybe you have better idea for this, like hoping I missed checking a checkbox or something :)

A lot of words, easier to show the problem with a video, so here it is:

 

 

[bmyagkov]

Hello!

@brentskeggHow would the actual behavior be impacted if the "Lerp" state on impostors were changed from the current "Lerp With Separate Opacity Map" to "Disable" and the "Inf" value was set for the "Visibility" parameters? Could you create a simple sample scene using default LandscapeLayerMap and ObjectGrass objects? Then, simply archive it by right-clicking the ".world" file in the asset browser by selecting "Export as Package" from the menu and share it with us using any file-sharing service or attach it to this message. This would assist us in understanding what's happening as the current behavior seems quite strange.

Thanks!

[brentskegg]

Hello there!
It did improve a little if I disabled the lerp option. But the problem does not lie in the engine itself, its more sort of a general graphic problem when using alpha testing for transparency I guess. For instance if I change the transparency preset setting for the impostor to opaque instead of the alpha test I get the full visibility distance, but then ofcourse I see a rectangular/quad shapes instead of a tree for example.

I've attached a small test where I have infinity as a visibilty setting for the impostors but with the fov at 60 I can only see impostors to about 6000 meters. If changing the fov you will see the same behaviour as in the previous video, at fov ~30 I see the "whole forest" (from 0,0,0).

Its just the standard scene with the free spruce vegetation add on as cluster/impostors, no need for the landscape.

Hm, I guess I could try to use two impostor nodes, one with opaque transperancy furtherst away and alpha testing for the closest one. And then calculating the transition range between them using the fov. Feels like a little hack but I guess it could work.

Thanks!

impostortest.upackage

[brentskegg]

After eating some breakfast I tried my litte hack with another imposter node furthest away that uses the opaque preset setting for transparency. Although not perfect its a viable option, had to adjust the density of that impostor since its quads and takes up more pixels than the normal tree impostor.

Just have to come up with some equation for the transition range depending on the fov, or just have a fixed fov all the time.

So you can close this as solved if you dont have some other magic fix for this! :)