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Grass is too dark & gappy

Hello there!

This is how my grass currently looks like: http://i.imgur.com/531c9t1.png

Obviously, this doesn't look good or realistic.

What can I do to

  1. brighten it up and

  2. make it render less gappy?

When seen from afar parts of the grass disappear even though the ground is almost fully covered with it.

Product Version: UE 4.8
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asked Sep 04 '15 at 03:21 PM in Rendering

avatar image

Rhidor
16 5 8 10

avatar image Logan Bailey ♦♦ STAFF Sep 04 '15 at 10:41 PM

Hello Rhidor,

So from the screenshot I can see that the grass is not catching the light like you want. This results in a dark material.

To address the first question. If you would link me a screenshot of your skylight settings. Your skylight controls much of your ambient light and increasing it's values can lighten your grass considerably.

For your second question I would look at the Dithered LODTransition inside of your Material properties. Through this you will be able to use the DitherTemporalAA node which you can use to control how much of an offset you have when the grass is drawn in your project.

Not being able to see foliage a ways off is due to your cull distance. Adjusting the Max Cull distance for your foliage should allow you to see foliage at whatever distance from the camera you set it to.

If you still have questions about this please feel free to post again.

Thank you,

Logan

avatar image Rhidor Sep 05 '15 at 12:00 AM

Here are the screenshots of my SkyLight settings:

  1. http://i.imgur.com/fmyJtsm.png

  2. http://i.imgur.com/G59onty.png

I tried to find the Dithered LODTransition, but I'm still not used enough to the engine to find it. I had about 4 different LOD settings when I opened up my material (if that's even the right place) but a DitherTemporalAA node was nowhere to be found.

I also don't really see where I can adjust the cull distance. I opened up my grass material in the StaticMeshEditor, opened up the Static Mesh Settings, but the option to set the default settings to InstancedFoliageSettings wasn't available, thus a min/max cull distance change wasn't possible.

avatar image Logan Bailey ♦♦ STAFF Sep 05 '15 at 03:35 PM

Hello Rhidor,

In regards to your skylight. Increasing the intensity of your skylight will allow for more ambient light to be cast in your project. This should lighten up your grass. You will need to adjust the intensity to a setting that looks good to you.

I have found a simpler method for you to try. It deals with a culling volume. What you will need to do to add this is go to your modes tab and type in Cull. This will bring up a Cull Distance Volume.

Here is a nice tutorial on YouTube. This gives a fairly simple but effective explanation of how the volume works. In a nutshell, the volume calculates how large or small an object in your level is and then at a distance that you set it will disappear.

There are ways to set up grass through the new LOD volumes that can control how thick your foliage is calculated through world position offset. However, I recommend starting by manually painting foliage through use of the foliage tool. You can keep what you have, just fill in the gaps where you think the grass should be thicker. This gives you more control and allows for a more artistic look rather than a computer generated number. I recommend starting here and then exploring later once you have a handle on this method first.

https://www.youtube.com/watch?v=tnRgb6Asteg

I hope this helps,

Logan

avatar image Rhidor Sep 05 '15 at 06:05 PM

When the SkyLight intesity is increased, the scene looks terrible. There's a change with the grass, yes, but it's not very noticable. Very noticable however are other objects, which become just much too bright. Is there no other option?

I have watched the video before I saw your reply already. It's just not usable to me, as the objects in the video are actors, whereas my grass is painted in through the terrain. The methods shown in the video simply do not apply to my situation, sadly.

I also added the Cull Distance Volume to my level like this (http://i.imgur.com/TMGoM3S.png), but changing any of the settings didn't work for the grass.

The foliage tool won't help. I have no problems with empty spots - the big ones in between on the screenshot are there on purpose - as the entire ground is covered with grass already. The problem is that I simply can't see all of it anymore when the camera is even a small bit away from it.

Sadly, this did not help yet.

I need to know how to manually brighten up just the grass, and how it won't disappear so quickly.

Again, my grass is painted onto the landscape. Normal actor rules won't apply here.

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1 answer: sort voted first

biggest problem I see is that you need to carefully color match the grass on the landscape to the grass meshes. The landscape grass is either way too bright or your mesh grass is way too dark. Once you match them, the "gappyness" will go away. There is no avoiding gaps with grass, they have to disappear at some distance you just need to make sure that the color and brightness are similar when that happens.

Also maybe try using the 2sided foliage lighting model. What are you doing for normals? Sometimes pushing the mesh normals upwards a bit, or using spherical normals on them can help.

If you are asking how to brighten the grass, that would be in the material by multiplying the basecolor and subsurface color by scalar parameters that you can tweak. Also set a scalar parameter for opacity and tweak that, it affects the subsurface.

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answered Sep 05 '15 at 06:12 PM

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RyanB STAFF
2k 55 24 118

avatar image Rhidor Sep 05 '15 at 06:49 PM

I'm using the grass ground texture found in the starter content and the grass from the Kite Demo pack. I'm not really sure what normals are (Normalmaps?), but I've changed nothing from the default settigns of those.

How would I use a scalar parameter and what should I link it to?

avatar image RyanB STAFF Sep 05 '15 at 10:56 PM

Open the material and find the texture node going into "base color". Add a multiply node, connect the texture to A and the scalar parameter to B.

Then do the same thing and plug the result into "Subsurface color" and select the material node and set the shading model to be 2-sided foliage. Then place another scalar parameter for opacity.

avatar image Rhidor Sep 06 '15 at 02:56 PM

Like this? http://i.imgur.com/PvoXyjT.png

The link to subsurface color is grey, for some reason. Important?

The preview now shows the grass ground texture completely black, but it still works in-game.

I also have 4 different textures used in the grass foliage model. Where would I change what? I don't seem to find the "material node" and it's settings.

Wow. I know nothing, it seems. I hope you can still help me. A screenshot of how it's done correctly perhaps?

avatar image RyanB STAFF Sep 06 '15 at 04:25 PM

select the material node and set the shading model to be 2-sided foliage. Then place another scalar parameter for opacity.

you need to name your parameters something other than none otherwise they will all have the same value always.

avatar image Rhidor Sep 06 '15 at 05:08 PM

Where is the material node? I can't seem to find one. Would it be called anything specific?

Where would I link another scalar parameter to other than opacity?

Is what I did so far correct (except from the naming)? If yes, what values in the scalar parameter would I have to change to brighten up the grass?

avatar image RyanB STAFF Sep 06 '15 at 06:23 PM

its just the main block node where you connect everything. or you can just click anywhere on the background. then it should show you the main material properties on a menu on the left. you should see a group of settings under "material".

as far as what value to use for your scalar parameters, just try entering values and see how they look. that is the idea behind a scalar parameter. the changes should show up in realtime without having to compile so you can just scrub the value and look at your scene.

avatar image Rhidor Sep 07 '15 at 01:20 PM

Alright!

Most of my textures/materials already had some settings for opacity/subsufrace, so the only change I really did was to the base color.

I was able to brighten up my grass significantly, and I also added a scalar parameter right after my grass texture in the terrain.

I was able to create this: http://i.imgur.com/CBcT1YH.png

(The mountains in the background are still untextured)

For anyone reading this, I also increased the grass density.

It's still somewhat noticeable to see the grass appear/disappear in the distance, but only if you look closely. This will change when more detail is added.

Thanks to everyone who helped!

avatar image RyanB STAFF Sep 07 '15 at 03:56 PM

looking way better!!!

you can try breaking up the distant tiling grass texture by blending to a slightly scaled up version.

For the kite demo we actually used a different texture on the grass in the distance, soemthing that was much more uniform texturally that didn't have any splotches. But finding a texture that you can blend to that looks similar can be challenging. Sometimes using the same texture at a bigger scale works.

The material function "camera depth fade" is perfect for that blending.

avatar image Rhidor Sep 08 '15 at 08:12 AM

For now I'm happy with the results, but I'll definitely keep in mind what you wrote. I just wanted the place to look somewhat decent now, working on the details will come at a later point.

Thanks again!

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