Grass tiling pattern is visible

[Amerio.Stephane]

Hello,

When using a high density value, the grass tiling pattern is strongly visible:

While this would be perfect for corn fields, it's very disturbing for mountain grass. (here density=3, alpha=2 just to emphasize the effect for the capture).

Any way to fix that?

[morbid]

Hello Stephane!

Indeed, looks like a perfect solution for crops harvesting sim :)

Could you try changing the step parameter for this grass object? Step is basically the size of a grass cell. It is better to keep step value corresponding to grass object size (size should be divided by step without remainder). We have the task for changing this unobvious rule for grass parameters.

If changing step parameter doesn't solve this issue, please send us material and grass node.

Thank you!

 

[Amerio.Stephane]

I tried all sort of combination of step, subdivision, and the tiling is always really apparent with a high density. The fact that the "wind" field animation is also spatially tiled worsen the effect.

ObjectGrass.zip

I would agree the density here is pretty high, but maybe the tiling size is also pretty small inside the engine :)

Maybe a solution would be to use internally a different "seed" for each "step" cell.

[morbid]

Indeed, the repeating pattern could be seen from the distance easily.

Right now there's no way you can totally avoid this, but tweaking grass visibility distances and other settings could help:

• It's better to use ObjectGrass with such high density only with low visibility distance values, where you just can't see the tiling
• custom masks also should make it look better

May I ask you, why would you create such dense grass? It's could affect performance drastically.

We have plans for ObjectGrass optimization, I will describe your request for the dev team, but it's unclear when exactly some changes will be done.

Thank you.

[Amerio.Stephane]

I tried with multiple grass overlayed and different seeds, but even then the tiling pattern is still visible. Looks like the "grass" meshes themselves are set up on a regular grid.

One of our scenario is landing the helicopter in a clearing surrounded by trees, while the pilots gets altitude and wind clues from the grass and trees moving. Also, the airport landing strips are surrounded by grass. So I wanted to see how much detail I can get, compared to other solutions. The easiest way was to fill the ground with grass, on a large distance to avoid popping. I agree ideally the grass would only need to appear when we're close, but there may be another issue with grass shadows that make then "stand out" too much on the ground when the appear, so I had to push up the density and the distance to try and hide that.

[morbid]

May I ask you to list crucial criteria that grass should comply in your project?

I mean not only the tiling issue but also shadows and maybe something else?

Thanks!

[Amerio.Stephane]

From most important to less important

1. animated with aircraft rotor wind (the whole point of having grass is to give the pilot the sense of height and ground proximity with the rotor wind)
2. no eye disturbing issue (no tiling, no popping, no shading artifacts)
3. blend with the below ground (more of an artist problem, agreed, but it means no shadow suddenly appearing/disappearing for instance. Most of the time, the grass shadow should be very dim, almost unseen; but when simulating bushes or trees the shadow should be stronger, hence the request to be able to tune it independently)
4. covers a wide area OR don't notice when the grass "fade in"
5. animated with global wind (only usage would be with strong, directed, wind, not gentle flow, so it's important that the movement is somewhat realistic if possible, with no tiling, such as here:

) Usage of strong wind is to hint the pilot on the wind direction and force. Both global wind and rotor wind must co-exist (we only need one rotor wind).

[morbid]

Hello Stephane,

On 7/6/2018 at 11:00 PM, Amerio.Stephane said:

animated with aircraft rotor wind (the whole point of having grass is to give the pilot the sense of height and ground proximity with the rotor wind)

Is tiling the only issue that stops you from using Field Animation?

On 7/6/2018 at 11:00 PM, Amerio.Stephane said:

• no eye disturbing issue (no tiling, no popping, no shading artifacts)
• blend with the below ground (more of an artist problem, agreed, but it means no shadow suddenly appearing/disappearing for instance. Most of the time, the grass shadow should be very dim, almost unseen; but when simulating bushes or trees the shadow should be stronger, hence the request to be able to tune it independently)
• covers a wide area OR don't notice when the grass "fade in"

Speaking of tiling, have you tried to combine different grass nodes with manually created masks? May I ask you to take a look at the attached screenshot, you'll find there an example of 3 different grass nodes with masks.

Popping could be solved by fade value and custom detail texture that lies under the grass. Detail layers could visually blend the transition between grass and terrain.

For shading, please, check my answer here. Hope this helps. By the way, on the attached screenshots screen space shadows are used.

On 7/6/2018 at 11:00 PM, Amerio.Stephane said:

animated with global wind (only usage would be with strong, directed, wind, not gentle flow, so it's important that the movement is somewhat realistic if possible, with no tiling

For now, you can simulate global wind that moves trees and grass only by FieldAnimation.

I've described your needs to our team according to the priority. Some of the requested improvements will require major code refactoring, so it would take time. If you have any additional feedback on this - don't hesitate to share.

Thank you!

 

[Amerio.Stephane]

4 hours ago, morbid said:

Is tiling the only issue that stops you from using Field Animation?

No, tiling is not preventing me to use Field Anim ! It's even really nice when the grass density is lower. It's just that it looks too regular not to attract the eyes and bring remarks from pilots, sadly.

The tank demo and its grass is really impressive, and it's also difficult to apply it directly when your ground texture must match a real ground (sat image). Not sure how to do that. The noise texture is perfect for matching grass color to ground color, but I can't set it to use the landscape texture.

[morbid]

20 hours ago, Amerio.Stephane said:

ground texture must match a real ground

As I mentioned before, you can control ground color with details layers, so the transition between areas with and without grass triangles wouldn't be too harsh. Haven't you tried this?

Probably, the fastest way to create mask for grass detail is "Mask by albedo " feature.