Grass is created just below the terrain

[Amerio.Stephane]

Hello,

When creating Grass over a TerrainGlobal (created with the Landscape tool), on some places, the grass is planted below the terrain.

This result in some no-grass patches on the terrain, even though the grass desinty is high, the terrain only has one LOD, and the terrain is not very steep.

It looks like the grass interpolation grid does not fit the terrain below.

Thanks for your help.

[morbid]

Hello,

as far as I see you've faced some limitations with intersection calculation. The geometry you see here is not the geometry that was used for grass & terrain intersection. Due to tesselation process (you can read a few words in doc on terrain) geometry may vary.

Better results could be achieved with more detailed elevaion sources. See the screenshot attached.

Also I'd like to note that ObjectGrass usually used with such low density sources for forest imitation. You can create imposors and add grass_impostor_base material. Obviously, tree is bigger than grass and you can enlarge impostor by tweaking Min\Max Height paramter. Bigger grass will be visible in such areas.

However, this is not the behaviour you may expect. The solution for this issue will come with new GPU driven grass object. Unfortunately can't give you any ETA on this.

[Amerio.Stephane]

Ok, understood. Is there any way to artificially increase the terrain resolution at creation time with the landscape editor?

[morbid]

Landscape Tool has no such feature. Have you tried looking for desired data in Global Mapper or other sources?

[morbid]

Stephane, actually, there is a way to improve intersection.

You can use houdini digital assets (hda). Such asset could be configured to create more dense areas within your terrain.
I've tested your data with simple hda that increased elevation density up to 18 m/p and result became much better.

You need a Houdini license to use this feature.

[Amerio.Stephane]

Hi, I'll look into it. Just a few clarifications:

- the documentation states "Please note, that trial version does not allow to use Houdini assets in the Landscape Tool."- Does it mean the Unigine trial version does not allow, or the Houdini trial version does not allow?

- the Houdini license is only needed for the generation of the terrain, or for every runtime that will use the terrain?

-do you have any video/pictures that would show off what this feature is really capable of? It does look promising, but I could not see any demo of it.

-would the performance still be 60fps with a 200x200km database @1m/px (both imagery and elevation) ?

Thanks again

 

[silent]

Hi Amerio,

1) Houdini trial version, we have no limitations on our side
2) Houdini required only for the generation and not required in runtime
3) No video, but some detailed tutorials with Houdini assets usage is planned for the release in the future
4) I would say yes, but please keep in mind that 1m/px and 200x200km area will never physically be able to fit into the GPU Memory, so you might have to tune the first LOD visibility distance a bit

Thanks!

[cheng1007056724gmail.com]

HDA file can import Ungine?This is very cool.but how to import and use HDA file?Looks like Unigine not support HDA file,please give a workflow

Edited December 10, 2017 by cheng1007056724@gmail.com

[silent]

16 hours ago, cheng1007056724@gmail.com said:

HDA file can import Ungine?This is very cool.but how to import and use HDA file?Looks like Unigine not support HDA file,please give a workflow

You can check the Landscape article in our documentation: https://developer.unigine.com/en/docs/2.6/editor/landscape_tool/#procedural_refinement

[cheng1007056724gmail.com]

On 12/11/2017 at 12:08 PM, silent said:

You can check the Landscape article in our documentation: https://developer.unigine.com/en/docs/2.6/editor/landscape_tool/#procedural_refinement

Cool,but how does houdini assets import Unigine?include simlation and phsical computing,that need houdini engine for Unigine.So,have you?

[silent]

As you can see in the Landscape tool there is a special filed to load .hda asset. Only landscape tool can work with Houdini assets and they should only modify the terrain textures.

[Amerio.Stephane]

Hi, I'm trying to implement a basic HDA to test Houdini with Unigine.

Could you maybe post a sample HDA for us to learn from, or post a short tutorial on how to design one for Unigine?

Thanks.

[morbid]

Hi, Houdini could be tricky for new users :)

We have plans for releasing a sample with Houdini features demonstration. Right now I can suggest you a couple of .hda files for a test.

First one (condense.hda) is extremely simple, it allows you to create inset with custom density in terrain height. The other one is from I/ITSEC project, it processes both heights and masks. I'd like to note that flow presented in terrain_ref_itsec.hda is not the only possible way of terrain refinement.

Also, our tech artist suggests these videos to start with terrain in Houdini:

• https://vimeo.com/209235365
• https://www.youtube.com/watch?v=xXNaw5jZDUY
• https://www.youtube.com/watch?v=YQ6Ea-wHkpg

And these as basics of creating Houdini digital assets (hda)

• https://www.youtube.com/watch?v=sPfpikUp26E
• http://www.sidefx.com/docs/houdini/assets/create.html

By the way, we've improved the original behaviour in your case. Grass is intersecting with low-detailed terrain much better now.

 

terrain_ref_itsec.hda

condense.hda

[Amerio.Stephane]

Thanks for the samples and links. I think a more in-depth explanation of HDA integration is direly needed though. I'm really feeling this is a very powerful feature and I may be missing something big if not used correctly.

About the hda samples, they use a node "externator" that I believe is not part of Houdini default installation, but looks essential to Unigine integration. Can you confirm ?

Also, thanks for the enhanced support for grass and low-detailed terrain :)

[morbid]

You're welcome!

Quote

they use a node "externator" that I believe is not part of Houdini default installation, but looks essential to Unigine integration. Can you confirm ?

Yes, this node is used to set the attribute that distinguishes internal and external volumetrics. In some cases, final Houdini output needs some temp data that is basically unwanted in landscape project.