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3D Grass on custom aerial image

F

fabs79

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germany
Hi,

I have a question concerning the placement of 3D grass on custom aerial images. In an older thread from last year someone stated that the sim engine automatically places 3D grass according to the "green-ness" of the underlying satellite imagery, so if a part of the aerial image is bright green, there will be dense high 3D grass, while on brown or grey parts of the aerial there will be no grass.

Now I have the problem that although I use a custom aerial image for my scenery which is displayed correctly, the sim still places way too much high grass on it and I have the feeling that my aerial image is ignored when rendering the grass and that the sim instead uses the original Bing image which is hidden beneath my aerial image to decide where to place grass. One example: In the original Bing image the dirt strip runway I´m working on is wrongly colored bright green, whereas my aerial shows the correct dirt and mud surface. But still the bright green grass is placed everywhere just like in the default scenery. Although I know I can use invisible aprons to get rid of the grass completely, this also removes the small patches of dry grass that actually SHOULD be around the airstrip. So is there any way of using the custom aerial image as a basis of grass placement?

Thanks and cheers,

Fabian
 
Ok there is no Bing image hidden. The sim uses OSM data for roads and building placement, but it stops there. If you want your custom aerial image to reflect true colors, then you can edit that image before you process it to CGL, the same way you would edit out cloud shadows, or images of planes on runways.

Here is a really good example of the conditional grass effect. The island is blanketed with an aerial image, so there is no default ground anywhere. The Piper Cub is parked at approximately the start position for that end of the runway. You can see the yellow of the approach chevrons had no grass on it all all, nor does the white runway end stripe. These features are present only on the satellite image, they are not part of the airport; that is a simple invisible runway, some edge lights, parking, taxi and hold shorts, that's all.

ok.JPG


However, I think relying on image driven graphics, essentially allowing the scene to decide how to render itself, is going to cause headaches, "no Pinocchio, your interpretation of heavy grass on dark green surfaces has much too much immature enthusiasm to simulate how grass really grows." I think we all wish the simulator would just jump up and present us the exact scene we are imagining, but I think this desire is a consequence of the simulator allowing us to believe that is in any way possible.

Let me give another example. I was noticing how carefully the sim engine conforms to OSM building footprint data and the images of this, also illustrate my issue with default volumetric grass. This first image shows how well the sim mimics a building I know exists in that location, I've learned the size and shape of that building from reviewing dozens, if not hundreds of photographs.

osm.JPG


So now we get to see the aerial image I'm working with, poor quality, washed out, you can see a little corner of the roofline sticking out looks more like my roof, than the default.

osm2.JPG


I think this image captures the shortcomings of the automatic scenery well. First, we have this warehouse looking thing with the oddly round wall and we have tons of grass that from straight above, is almost completely invisible! Going back to the overhead image, my mind insists these are two different locations, they are not. Bear in mind, the first image is of what is intended to be a runway. The color variation between that and what is intended to be concrete tarmac, is all that controls the appearance of that grass.

Ok, for you to control grass "volume," with satellite image color only, that image would have to be so cartoon like in quality and color blending, that it would be useless as a visual representation of reality. You'd be better off to place dry grass where you want it. IMO, of course.
 
Thank you for you comment, the problem with placing grass polygons is that it also looks pretty unrealistic for the edges are drawn too sharply, it doesn´t look like natural growing grass, more like a mowed lawn, so it´s not a good solution unfortunately.
 
For polygons, the vegetation Falloff Distance controls blending into the surroundings and removes the sharp edge.
 
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