Texture questions

Started by yossam, February 17, 2016, 02:50:14 PM

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Ran across some good looking textures for plants...........they include color, spec, occ, disp, and normal maps for each. My question is about the occlusion map...........is there a way to use it in TG? I thought maybe in the specular roughness slot............ ???

Example below...............I don't see much difference, your opinions please.


I do not think there is a way to use an occlusion map inside of Terragen. That would have to be ambient occlusion control through a imported image. It certainly would be a nice option to have within the Default shader. Specular roughness is different from ambient occlusion sense one is for reflection specularity and the other for environmental lighting.


Quote from: yossam on February 17, 2016, 02:50:14 PM

Example below...............I don't see much difference, your opinions please.

Did a blink comparison and could see no difference at all between the two images.  Are you sure the images are loaded in their proper slots (Color image, reflectivity image and displacement image),  and sliders are set to some value other than '0'?


j meyer

If you want to use an Ambient Occlusion map in TG one way would be to
combine it with the diffuse (color) map in your favourite layer based
image editor.


J meyer is right. Ambient Occlusion is usually used multiplied over the diffuse texture or image to strengthen shadow areas. So in your texture, use two image nodes and a multiply colour node, then plug the result into the diffuse input of your default shader. You can use AO to do things with specular, like mask out reflectivity within shadow, if that was something you were looking for. Although AO is most effective working with diffuse colour.


Could you post a node diagram...............what I tried didn't seem to work.  :-[


But how do you know before where the shadows are? And if you have a texture with areas that (should) have intrinsic shadow, you might as well enhance those before, instead of using 2 image maps. Just curious.


Have a look at the attached image. I haven't got a model with an AO baked texture to show you a render unfortunately. I tend to use a rendered AO pass of the scene / component to composite with.

What this does is add some definition and kind of dirt to gullies and corners that wouldn't see as much light as a flat surface. It's not an accurate process, it's an artistic effect.

A very similar process to the Occlusion Weight / Bounce to the Ounce settings in the Render/GI panel, where you see the image pop a bit more as shadows become slightly darker around details when the render finishes its last bucket.



Ah, rendered AO pass. That explains.


The maps feeding the multiply color, are they thru an image map shader? Set to "UV if available"? For some reason this is harder than it should be(for me).  ::)


Quote from: yossam on February 25, 2016, 02:34:21 PM
The maps feeding the multiply color, are they thru an image map shader? Set to "UV if available"?


Is the Colour Image slot clear within the Default Shader node?

If you want me to have a look at the model and set up a TGD for you, ping me an email.


Quote from: j meyer on February 25, 2016, 01:17:16 PM
You'll find a crude illustration here

Good illustration of what we're talking about.

I think the term 'Dirt Map' is more appropriate to the effect. It's kind of where a cloth can't reach to get rid of grime.


Thanks Richard.

There were a few things that needed sorting out, the Image Map shaders need to Use UVs, but also they needed scaling, positioning and repeating, which is probably why it didn't work for you and I forgot to mention that in the post above.

I've attached a TGD with the node setup in the Object node so others can have a look, although they will need to plumb this into their own object texture shaders. I also switched off Ray Trace Objects in the render node to have a look at the displacement map and see how that works across the model (with it on, it treats displacement like a bump map which doesn't distort edges). I'd probably want to split the object into a third piece so that I could displace the main trunk more heavily than the mid sized branches.

The two images below show the AO effect on and off. It's an artistic thing on whether it works for you. I used a Colour adjust shader to lower the black level to -5 so that the blacks in the texture become 33% grey.

Warning tech babble....
By creating a range of white to black to be effectively 1.5 times what it was by using the Colour Adjust shader, the extra .5 is a third of the original colour range. So black level at -1 will turn the black to 50% grey etc.