A few high-resolution ground textures

[erik]

Ok, so the infrastructure is basically available but it takes developers to optimize the results. Fair enough.

One thing that I just realized is that creating detail textures is much easier than creating textures of, say, 10km by 10km size so that speaks in favor of a detail-texture bottom-up approach instead of a large-scale texture top-down approach.

Erik

[Thorsten]

See it as a piece of art - you have different texture channels to feed, you have mixing factors to play with - using them you can do top-down or bottom-up, you just have to see what works best for your particular problem. There's no recipe that works for everything.

What I find mostly lacking are good large-scale textures for agriculture or 'complicated' landclasses that aren't really one color only - agriculture as it is looks spookily similar across the world...

[vnts]

Ok, so the infrastructure is basically available but it takes developers to optimize the results. Fair enough.

There are a few things that could use c++ code support to be improved - including for airport surfaces - maybe for WS 3.0. For airport surfaces, the info needed from c++ side that would be needed to place and scale position dependent (large scale) wear&tear and deposits for runways/aprons/taxiways: a) 2d uv coords (with a distance from start coord similar to OSM2City roads), b). width of runway/taxiway at each point in meters to scale and place things like rubber deposits, c). length of runway/taxiway in meters so the shader always knows the position, d). distance to things like intersections in meters and type of intersection to change placement of rubber deposits etc. The info can come from vertex attributes, uniforms, or from a giant WS 3.0 style raster image (texture).

Kind regards

[erik]

What I find mostly lacking are good large-scale textures for agriculture or 'complicated' landclasses that aren't really one color only - agriculture as it is looks spookily similar across the world...

I've searched a bit for good quality aerial images and good base material is rather easy to find but unfortunately everybody seems to agree on CC-by 3.0 which sadly is incompatible with the GPL.

Here is one such example:


Erik

[Thorsten]

Well, there might be camera drones in enough private hands to do aerial photography more regularly and not depend on databases these days...

[erik]

Yes that would be great. Unfortunately I do not own a drone and wouldn't be able to use it anyhow living close to an active airport. Maybe it would gain more attraction if it was an combined effort of FlightGear and OpenStreetMap?

Erik

[frtps]

I think OpenAerialMap is the OSM equivalent for aerial photos. There's also the option of just writing to people to ask for a CC-BY-3.0 relicense to CC-BY-4.0, often the 3.0 is just what was the lastest CC licence at the time.

[erik]

I've thought about asking for a different license but it will become an outstanding-license-question nightmare really quickly.
It may work for a photo or two but when it reached 20 outstanding requests it becomes a problem.

Erik

[Johan G]

I think OpenAerialMap is the OSM equivalent for aerial photos.

Judging from the terms "All imagery is available to be traced in OpenStreetMap", and some items in the user interface (like "Open in iD editor" and "Open in JOSM") it seems like on of the intended uses is for tracing to OpenStreetMap, so pretty much yes.

Seems to be a great reference for textures. Some of the images have ridiculously high resolutions.

[erik]

Seeing that the airport keep in the comparison images stuck out like a sore thumb I've taken the liberty to redo them for normal season:

and for autumn:


Erik

[erik]

As a follow up I've color matched most of the current textures so they have the same hue, saturation and brightness. This is pushed to the base package already.

Here is an example where the borders of the different crop lands are really hard to notice (and spot the airport):


Erik

[erik]

Heh on my laptop I noticed I've overwritten another image with the same name which will cause the old image to show up the browser. You might need to F5 refresh the cache to be able to see it.

Erik

[V12]

Amazing ! Much better than original out of the box.

[bugman]

... agriculture as it is looks spookily similar across the world...

In most cases I agree. However some places are quite different. E.g. some places, especially in eastern Europe, have very narrow rectangular fields:

Zellerndorf 2051, Austria

Some have huge fields:

Australian Agricultural College (Longreach Campus), Longreach QLD 4730, Australia

Some have quite beautiful patterns and colours:

Xiaochenxiang, Li County, Hebei, Baoding, Hebei, China

There is a lot of interesting variety for artists to dig into

Regards,
Edward

[vnts]

When reviewing the updated grass textures in FGData I ended up looking in some depth to see what was going on with airfields..

Testing the new grass textures, I found..

Seeing that the airport keep in the comparison images stuck out like a sore thumb..
Erik

..that there already seems to be a default structure texture called grass_overlay.png. It seems the structure is stored in alpha channel in inverted fashion and the RGB channels are empty. It seems to be implemented this way to be consistent with a standard overlay format, Done this way it gives basically the same equation as my test version (with some bonus unevenness noise added). I never looked or bothered about it as I thought it must have something to do with the geometry shader volumetric grass 'overlays'. Therefore the ground rendered by airfield.frag has grass detail from a structure texture texture like the one I made.

I had thought the current detail was from some (homogenous looking) math noise thing, not a texture.

Normal grass close up - that does not
[img]

The current sturucture is based on the grass photo airport_grass2.png. The difference in the structure texture I made from your photos is your original grass photos are less uniform, and have grass and plant leaves.

I noticed the textures had been updated, replacing airport-grass-png and airport-grass-autumn.png.

A fairly common way to add new textures seems to be to add a 2 after it, looking at the textures forlder. Some textures are used by different effects to what the name suggests in different ways. Not sure what Gilberto's plans for the texture was (it seems various other textures were derived from the grass one). Maybe(?) the names of the updated textures should be changed(?).

Looking at the airfield effect, and tracing the n= vales, texture units, and unform names:
- n="13"(default) : Grass texture
- n="14" : Overlay texture (currently contains fine structure in the alpha channel)
- n="15" : Grain texture (a fine grass coloured texture similar to your first texture)
- n="20" : Volumetric geometry overlay only - colour texture

(There's also a densityTex sampler 2d in grass-ALS.frag that's no longer used - doesn't affect anything)

Doing a text search in Materials/regions/ to see where files are used:

airport-grass.png:
- hawaii.xml - this seems to be the green tropical grass texture. Probably will end up being used in the Carribean

airport-grass-autumn.png:
- grass.eff - texture defined as a volumetric grass blade colour texture /everywhere/ rather than just a grass texture. Texture n="20" doesn't appear to be re-defined for much other than for Hawaii.
- global-summer.xml , azores.xml - default grass texture. It's not a texture of autumn specifially.

airport-grass-overlay.png
- southern-europe.xml - the full 4 texture set is used here but with the overlay set the same as the normal texture so it has no effect (misc cleanup?). Overlay texture is still used as a structure texture but in the n="15" slot (works the same).

Searching for "AirportKeep" shows the other types of grass textures. I see California-grass.png is popular (my new version had a 2 to be on the safe side, I'm not sure about replacing the airport keep with texture detiled to be used with the agriculture effect with maximum large scale structure). corse.xml uses a 4 texture set, and mostly interpolates between two variants or something (possible misc cleanup? there's an additional default <texture> and an n="13" that refer to different textures but might not have any effect.).

Some relevant controls:
- <overlay_alpha> higher value means the blend is more towards the overlay (structure texture in this case). Default is 1.0

- <overlay_bias> There's some uneveness in blending. Higher values bias the blend towards

- <use_color_overlay> A boolean option which tweaks the amount of red in the ground texture /slightly/ using math noise a bit similar to your autumn texture - but this is in addition to the FG autumn effect. Default is 0. africa-mediterranean.xml uses this. <grit_alpha> has a slight effect on this, but that's the only control which does.

As usual with ALS there are a lot of options, and lots of room for improving (and adding local definitions) in even the current well developed areas. Only one or two places tweaked the volumetric grass balde colours. Maybe one place sort-of used the 4 texture controls, and that was for interpolation between slightly modified textures on the same scale.

----
Current grass with subtle homogenuos strucuture. ENBR


Grass structure from your high quality non-uniform photo. It's inverted (GIMP > Color > Linear invert) to fit FG's overlay format with black RGB to create the same equation as before.


Final structure texture: https://www.dropbox.com/s/m42d0cjb0lene ... e.png?dl=0

I had a overlay magnification of 15.5, but it may have been too high. Try 5+.

Grass strucutre applied. <overlay_alpha> = 1.0


Grass structure applied. Brightned slightly by using <overlay_alpha> = 0.85


ENBR is covered by global-summer.xml. The structure texture needs to be changed for other areas for which it's appropriate (e.g. not desert/sandy, or gravel).

AirportKeep (I manually deleted some parts using n="15" without testing but this should work ok)

Code: Select all

  <material>
    <name>Grass</name>
    <name>Airport</name>
    <name>AirportKeep</name>
    <name>Greenspace</name>
    <effect>Effects/grass</effect>
    <texture-set>
      <texture>Terrain/airport-grass-autumn.png</texture>
      <texture n="13">Terrain/airport-grass-autumn.png</texture>
<!-- Modified: grass texture experiment -->
      <texture n="14">Terrain/airport_grass_structure.png</texture>
<!-- End modified -->
    </texture-set>
    <parameters>
      <grit_alpha>0.4</grit_alpha>
      <use_overlay>1</use_overlay>
      <overlay_bias>0.5</overlay_bias>
      <use_color_overlay>0</use_color_overlay>
      <base_layer_magnification>1.0</base_layer_magnification>
<!-- Modified: grass texture experiment -->
      <overlay_layer_magnification>15.5</overlay_layer_magnification>
      <overlay_alpha>0.85</overlay_alpha>
<!-- End modified -->
    </parameters>
    <xsize>256</xsize>
    <ysize>256</ysize>
    <light-coverage>4000000.0</light-coverage>
    <diffuse>
      <r>0.93</r>
      <g>0.95</g>
      <b>0.93</b>
      <a>1.0</a>
    </diffuse>
    <specular>
      <r>0.1</r>
      <g>0.12</g>
      <b>0.1</b>
      <a>1.0</a>
    </specular>
    <shininess>1.2</shininess>
    <solid>1</solid>
    <friction-factor>0.7</friction-factor>
    <rolling-friction>0.1</rolling-friction>
    <bumpiness>0.1</bumpiness>
    <load-resistance>1e30</load-resistance>   
    <!-- uncomment this to get volumetric grass on airport keep-->
    <!--
    <wood-coverage>10.0</wood-coverage>
    <tree-texture>Trees/grass_blades.png</tree-texture>
    <tree-varieties>1</tree-varieties>
    <tree-range-m>200.0</tree-range-m>
    <tree-height-m>0.3</tree-height-m>
    <tree-width-m>1.0</tree-width-m>
    <tree-effect>Effects/tree-grass</tree-effect>
    -->
  </material>


----

Seeing that the airport keep in the comparison images stuck out like a sore thumb..

What elements exactly about the grass do you find lacking?

Are a lot of them resolved with the grass structure? What about by also switching on <use_color_overlays>

What things are still lacking after the grass structure is applied, and to what parts of the world is it applicable? (it's possible to introduce hues, detail, etc. from other sources).

----

The recent update to FGData

In light of the above possibly better to rename the upladed files as extra versions for now(?), and alter the materials files for specific regions if applicable. The grass photo texture you made (link) could also be added as a detail texture as it could be useful later.

The FG texture system wants summer dry textures with lots of things added procedurally (dust, autumn color change, winter brownness, wetness, snow , extra moss growth etc). The grass is green in a lot of areas, and this texture is also quite dark.

The new textures could possibly be used in higher latitudes where there is no a little grass in summer, especially the autumn variant. D-ECHO looked at keep (and keep photos) in northern areas so he perhaps had a better idea of locations. maybe useful as a general ground texture.

The new textures as is have issues with large scale sutructures. It's hard to do both large and strongly defined small scale structure without making the texture really huge in GIMP. Easier using FG.

Current keep from far away (there's some tiling, but this can be fixed)


Replacement texture used as is from far away



----

As a follow up I've color matched most of the current textures so they have the same hue, saturation and brightness. This is pushed to the base package already.

Do you mean matching the soil colours , or matching all parts of the texture?. Haven't seen the latest changes as I was looking into how keep grass works from the earlier grass change. Non-soil parts of the texture could legitimately have non-matching colours. The idea is to get the soil hues for each area to match. The saturation and brightness could vary - dusty, weathered soil on bare ground could be less saturated or lighter than soil on a agriculture field that is watered from a reservoir or underground sources. The saturation and lightness in leaf colours could similarly change for a watered field.

Given for instance, the complex situation with grass textures, I think it's hard to match textures without looking at inside the sim and how textures are used - as the same texture could be used as input in a lot of different ways for different materials around the world. Some of the source textures should maybe be left unmodified as modifying could irreversibly lose some information needed to localise for other parts of the world - e.g. decreasing saturation or intensity a /lot/ then increasing it would not give the same image.

When matching soil hues the best bet is to create extra textures for specific regions/soil types which is the way it seems to have been done (see Madagascar or California etc). It's probably useful to try to find the original version of the texture than lossily modify a modified/localised texture. The way I tried to fix California.xml was visiting the region, looking for anomalies, and possibly also checking with instantstreetview/photos. When looking into grass textures I text searched for the specific texture in materials/regions to see where and how it was used - not sure if that's the proper way but it works. I found the different ways the textures were used for the effect by text searching the landclass. Doing things region by region, and creating extra textures unless textures weren't sources and were only used locally, is probably a good way to do it.

There doesn't appear to be a way to reload materials textures. This would normally make it hard to try different effects in GIMP to filter the texture and quickly see it in-sim. It /is/ possible to trick FG into reloading by changing the name slightly and changing it back which is what I used.

Ideally there would be somewhere to upload sources of images, and the GIMP files so people in future could resume/improve things.

Kind regards