Smooth texture transitions

[Darthlister]

Hey all---

 

Working on an outdoor scene with a grassy plain that rises to a mountain. I'm looking at a grassy texture, then a rocky, then a granite-like one for the sheer mountain. Question is, how to effect a smooth transition from grassy to rocky to granite without them obviously being patch breaks.

Just getting into texturing heavily and any head's ups or links to getting started would be appreciated.

 

Thanks,

Rich

[Rodney]

Hey Rich,

 

Two things come to mind; layers and natural flow.

Natures flow (of wind, rain etc.) is what you are trying to emulate and layering a shortcut to get at that effect.

 

It can help to think in terms of hard versus soft in that your granite material is likely going to be the hardest so you can place that first.

If modeling it you build that with the thought that it is mostly immoveabe. Similarly if painted as a texture that is an area you want to define first.

It might help to consider straight edges, blocky shapes etc.

 

For the rocks we must assume they have either broken away from the granite or fallen away from topsoil that was once on top of the granite before.

Considering gravity and the effects of (mostly) water we can plot a general course they will flow to be deposited in the area between the granite and the grassy plain below.

Of course where the water moved the most will be where the dirt and smaller rocks tend to go.

Some of those rocks and even a few strategically placed pieces of granite might then be found here and there amongst the grass.

 

The grass then can only grow where it has dirt for it to take root and grow.

In somewhat a reverse fashion from the rocks the grass thins out as it encounters less dirt and rockier terrain above.

 

So with layering...

Thinking mostly in terms of black and white first set down your granite. This is primarily a matter of elevation. It is above the ground plane (which we can assume is sloping) or it isn't.

 

Then add your rock layer. This could be grayscale to indicate how far the rocks have moved away from their original source (i.e. black would represent the original location and white the farthest it has moved from the source..

 

Lastly add the soil layer and those things that will grow on it.

Don't neglect to add some soil at higher elevation to provide places for random seeds of life to grow.

 

The above is a bit more cerebral that it needs to be and basically you are just taking your three elements (granite, smoother rocks and grass) and layering them over each other.

I do think when building terrain it's a good idea to consider how nature (or man) would have formed the area though.

 

I should mention that gradient materials work well for some things like this.

The classic example is the terrain from Brain Prince and Eggington Studios.

The material textures the areas based primarily on elevation... so higher elevations would be granite colored while the lowest would be grassy green, etc.

Brian's tutorial may be online somewhere...

[Darthlister]

Rodney,

Thanks for the head's up. After playing with the gradients, I think I've got the barest handle on how to make that at least function. It doesn't look like I can have seperate bump textures for each level though--would you do a seperate gradiant for color and one for physical texture?

 

As for layering, I'm not quite sure how one would layer a texture..

 

Thanks,

Rich

[Fuchur]

hi rich... the texture needs a gradient in its alpha-channel (for tgas) or just needs to fade out tobthe edges (for instance with pngs) than use 2 decals and apply them after eachother to layer them.

 

it is possible to even layer a decal in itself i guess using 2 images with transparency in one decal (both in color mode) but i never tried that...

 

see you

*fuchur*

[Rodney]

I'm not quite sure how one would layer a texture..

 

 

In my estimation the secret to all texturing is layering.

 

It doesn't look like I can have seperate bump textures for each level though--would you do a seperate gradiant for color and one for physical texture?

 

There are so many approaches to layering that it might help to see an image of something similar to the look you want.

 

For the most part all you need is two layers to get most of the job accomplished; a height map (greyscale) and a color map.

You can create that either in A:M or in a program like Photoshop.

 

I'm adding two images to this post that I found randomly on the internet. They work pretty well out of the box with displacement (although there isn't really an element of granite mountains in it). My apologies if it's a bit dark.

 

Assuming you didn't want to paint any textures in an another program I'd say you could use A:M to create something similar. Just use a copy of your terrain model rendered from the top view. Experiment with various colors in the gradient material but I recommend using high contrast colors to start with (Red... White... I dunno... Pink?) That will help to more quickly get the right results. Note that for the sake of testing you could also use patch color to define basic areas of interest but you'd have to have a really dense mesh to avoid the 'jaggies'.

 

 

Edit: I should have flipped the normals on the grid.... I'll post another example as soon as it renders.

 

 

 

 

.

[Rodney]

I won't say the colors are to my liking but here's how the colors were made in the attached...

 

A gradient material with the second of it's attributes changed to another gradient material acts as a gradient for three colors to appear based (primarily) on height.

I toggled down the visibility of the color map from the previous decal but left the displacement map the same.

So when the gradient material is adjusted/animated it 'paints' the terrain.

 

I did remove the default Chor lighting and add a single Sun light as well.

 

 

mod1.mov

[Rodney]

And of course we can then layer in additional detail by adding new images to the decals:

 

(Here's a quickly added blue water level that uses the image's Ambiance Intensity setting)

[robcat2075]

Question is, how to effect a smooth transition from grassy to rocky to granite without them obviously being patch breaks.

 

If you are using hair for grass you can use a grayscale map to control its density to make the grass gradually thin out over some distance or even have some dense clumps that diminish over an area.

 

Unfortunately we can't use particle materials as components of combiner material

[Rodney]

Unfortunately we can't use particle materials as components of combiner material

 

 

I believe the workaround to that would be to use multiple instances of a particle material (or a number of different particle materials all driving different sprite images in a scene).

 

Perhaps even better, as you say, we can also use hair materials to drive the differences as we layer them in.

[Darthlister]

I dunno why I'm having a hard time getting the relationship between the greyscale map, the color map, and the model. I'm not an idiot, I swear

 

 

>>For the most part all you need is two layers to get most of the job accomplished; a height map (greyscale) and a color map.

 

This looks similar to that I've been doing in PShop, creating the TGAs for the Spaceknight flame, where the black is transparent. So, the lighter the grey, the higher the elevation? And you take a already existing texture, like crumple,dented, or planet, and somehow use the greyscale to tell the texture where to go on the model?

 

 

 

 

 

 

>>Assuming you didn't want to paint any textures in an another program I'd say you could use A:M to create something similar.

 

Nah, I wouldn't mind using something like PShop. I like what I've been able to do with it with the flame, but I'm just not sure how it's applied to the texture and/or model. Is this the same as texture mapping?

 

 

Thanks for the advice,

 

Rich

 

 

 

 

 

 

 

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[Rodney]

creating the TGAs for the Spaceknight flame, where the black is transparent.

 

 

This is an area where lots of folk get confused and it's largely because of the way Adobe/Photoshop handles transparency/Alpha Channels.

In short, black shouldn't be transparent... it should be an empty (alpha) channel.

 

A:M does have the transparency setting that can be set to allow for black to be transparent but... what if you want black in your image?

 

The trick with many paint programs is to remove/delete/erase the background which then leaves everything not painted (in any color) transparent.

 

To make matters a bit worse... the files can lose their transparency upon saving if one isn't careful to watch/understand the settings.

This is one of the reasons I like to suggest using A:M to create imagery wherever possible because upon selecting 'Alpha Channel' A:M assumes you want a transparent background/alpha channel. This is unlike other programs which assume you want the background white (or some other set color). Contrast this to A:M's camera background which you can set all day long to whatever color you want but if you opt for an Alpha Channel it doesn't matter what color you set because wherever nothing exists will be transparent.

 

This does get confusing because in order to show the alpha channel to the user it has to be some color (or in the case of Photoshop you'll see a checkerboard pattern). With many programs the alpha channel will display as black... because on the grayscale from white to black white represents 100% opaque while black represents 100% transparent.

 

Okay... having said all of that... when it comes to displacement... yes, lighter colors are elevated.

Consider mid gray to be zero elevation..... black to be lowest and white to be highest.

If you use a color image it will use that color's grayscale equivalent.

 

 

If you can, share an image of what you are working with and we can focus on that.

[Darthlister]

 

After cramming textures, gradients, bumps, etc. fro 12 hours, I think I'm getting there..any opinions would certainly be welcome. Am I on the right track? Need to learn water (cloth?) and still can't get the gradients to function exactly like I want, but will keep plugging...

 

 

[robcat2075]

If you add a "Turbulence" to a combiner it will make the boundary less straight.

 

Can you show us a real-life reference image of what you are trying to do?

[Rodney]

I'd definitely call that progress.