[SOLVED] "Density" parameter for grass and clutter

[Amerio.Stephane]

Hello,

Most of the time, the density value I use for mesh clutter and grass impostors is in the range 0.001-0.009, ie the limit of the precision of the displayed value.

My problem here is sometime, even though I copy pasted the value from the clutter to the grass, they seem to used very slightly different values internally, but enough to have impostors missing where clutter mesh is placed, or the other way around.

At this point, I don't know if the problem is that the values are actually different, but displayed as identical, or if your algorithm is somewhat different for the two.

(note the grass object was created with the new 2.7.2 impostor tool)

[vvvaseckiy]

Hello Amerio.Stephane,

Unfortunately we were unable to reproduce described behavior, could you please provide us some kind of a test scene with misplaced impostors?

Sorry for the inconvenience caused 

[Amerio.Stephane]

I culdn't reproduce it either, so either it's very specific, or I did something else wrong. If I stumble upon it again, I'll post it here.

Sorry :(

[Jinppa]

Hello,

I think I have the same problem with version 2.7.2.2.
There are much more impostors than tree meshes in the original mesh clutter and just like above, some impostors missing where mesh clutter is placed, or the other way around.
Density, size, seed, steps etc. are identical on the Mesh Clutter and the impostor Grass node.
I don't use terrains, the trees and grass intersect with a mesh. Both Mesh Clutter and Grass node use the same Mask Image, which is flipped in Y-axis.

Edited November 27, 2018 by Jinppa

[morbid]

Hi @Jinppa,

may I ask you to provide a test scene or values for grass and clutter parameters which cause this issue?

Thank you!

[Jinppa]

41 minutes ago, morbid said:

Hi @Jinppa,

may I ask you to provide a test scene or values for grass and clutter parameters which cause this issue?

Thank you!

Hi @morbid,

Here are the parameters and editor view comparison that shows how the impostors do not match with Mesh clutter meshes.

[morbid]

Okay, if you want to sync Grass and Clutter you also need to change step and subdivision for grass.

The shortest way to fix your issue is to make step for grass object equal to 100 and subdivision to 2 (Clutter step = Grass step / subdivision). Please, check this article: https://developer.unigine.com/en/docs/2.7.2/objects/objects/grass/#low_poly_grass

Thanks!

[Jinppa]

59 minutes ago, morbid said:

Okay, if you want to sync Grass and Clutter you also need to change step and subdivision for grass.

The shortest way to fix your issue is to make step for grass object equal to 100 and subdivision to 2 (Clutter step = Grass step / subdivision). Please, check this article: https://developer.unigine.com/en/docs/2.7.2/objects/objects/grass/#low_poly_grass

Thanks!

Hi @morbid,

I tried both the impostor "default values", identical values and also changing the step and subdivision to the values suggested to no avail, the problem persists.
Then I thought perhaps I should provide a sample scene with the same problem, so I created a new project, used the same parameters everywhere and everything works perfect! ... until I apply the Mask Image. With the same Mask Image applied to both nodes, the content of Grass node doesn't match the Mesh Clutter node anymore, which probably means that for some reason Mesh Clutter and Grass node do not use the Mask Image in a similar manner.

Any ideas why that happens or is there an easy fix for this? I might try Mask Mesh if if it works, but for the current task I'm trying to achieve it seems overkill in comparison to Mask Image which is easily painted in a matter of minutes.

[morbid]

15 hours ago, Jinppa said:

With the same Mask Image applied to both nodes, the content of Grass node doesn't match the Mesh Clutter node anymore, which probably means that for some reason Mesh Clutter and Grass node do not use the Mask Image in a similar manner.

Can you be more specific? What mask parameters are you using? I can't reproduce it that easy as you describe. A sample scene still will be very useful.

Thank you.

[Jinppa]

3 hours ago, morbid said:

Can you be more specific? What mask parameters are you using? I can't reproduce it that easy as you describe. A sample scene still will be very useful.

Thank you.

I'm using the same parameters as in the image I posted previously. Just a simple .tga format image (imported as  RGBA8) as a Mask Image, Min 0, Max 255, Mask Flip Y.
There's now a sample scene prepared, I'll send you a link to it in PM.

[morbid]

Thanks for the scene.

Grass indeed works in a different manner with RGBA mask, you may want to investigate it more carefully in our vegetation sample (SDK Browser -> Demos -> Samples).

Please, try to do the following:

1. reimport your mask as R8 texture, it could be done in Unigine editor
2. reassign converted mask to grass and clutter objects
3. save & reload world
4. check the mismatched trees

Worth noticing:

• Trees impostors work only with R8 mask. RGBA mask could be used for grass variations with one texture atlas per grass_base material
• Your mask could be much lighter if you'll keep only one channel, there's no need in 4 channels for the impostor and clutter synchronization.

Thanks!