Populating by card, handling orientation and other questions

[uuderzo]

Hello!

From time to time i try to grasp some Terragen, this year i decided to restart learning it, hope for the best

I'm trying to populate a landscape using tree billboards (cards as Terragen calls them) but i'm facing an issue with cards orientation.
I cannot make Terragen to place all the cards facing the render camera on the Y axis. Yes i can limit the angle range so that they "more or less" are facing the camera but it's not really true as they have all the same angle and the rightmost and leftmost cards are not really facing the camera. Did i miss some option?

About population color control: is a card population capable of being controlled by a color node? I cannot make it working.
Moreover, cards look rendered all the same, like if lighting contitions don't really affect them. I remember that Vue had an option to "shade" billboards so they look more natural. Is it possible in Terragen?

About population variery: if i'd like to mix different trees in a population, should i add separated populations one for each tree? Isn't it possible to populate with a single population so trees don't overlap using the distance parameters?

Thanks! Umberto

[Dune]

Welcome first of all. I do hope you get to grips with TG.

You can't rotate cards or anything so they always face camera. But I would advice to use 'real' trees anyway, quite some are available (for free).

You can use a power fractal or any other mask (like a distribution shader with slope controls) to mask the population; it has a masking input.

There's also a way to vary color within a population. I never use the external feature, but always use a power fractal inside the object, fed through a transform shader set to final position and fed into color tab of the default shader of that object.

And finally; yes, use several populations. Usually it's not very obvious if some trees overlap. In the wild they sometimes grow very close together too. If you need to be really accurate you can make very specific masks, ruling out one where the other is, but that's not very often needed.

[uuderzo]

Thanks for your reply Dune!

Ok, i'll use real 3d trees instead of cards. I tought that cards were more light on huge populations but maybe it's not true.

About color, i have to fully understand what functions i can use to color items as i noticed that many can be plugged into but not every one leads to perceivable results.

And, ok maybe i'm overlooking the population issue, sure overlapping trees are not so visible in the overall picture, and sure objects near the render camera can be manually edited to fix some weirdness.

Thanks! Umberto

[WAS]

Cards will only be cards, captured in their current lighting, so not very realistic. You'd have to match the lighting so it doesn't look odd, etc.

However, quasi-3d cards should be a thing, and not sure why it isn't. Kinda one of the main points to billboard/cards in 3d engines since the first FPS games (1980s). Fake 3D objects always facing the camera.

[Dune]

You can use whatever you like to vary color within populations. Experimenting a bit with pretty harsh contrasts and sizes of variation fractals may help. In the power fractal there are several ways to change the way the colors distribute over space. For every population the requirements may be different, being a small pop of flowers or a huge pop of trees.
For very distant areas you can use cards, and you could use 2-3 populations beside eachother along the horizon. With a minimum rotation, each pop on a different angle, pointing towards the camera.

[uuderzo]

@WAS sure a "always face camera" option would be nice to have. Anyway i think this could be an issue only in animations, not on stills.

@Dune thanks for the hint and the screenshot, i will study and elaborate on it!

Umberto

[sboerner]

@WAS sure a "always face camera" option would be nice to have. Anyway i think this could be an issue only in animations, not on stills.

There was a time when I wished for this as well. But Dune is right. Terragen is incredibly good at handling large populations of mesh objects, so it's easier (and best) to just use them. Good luck – I'm looking forward to seeing a render soon.

[WAS]

Anyway i think this could be an issue only in animations, not on stills.

Naturally you'd want the cards to face the camera, so even in a still, the exacting angle across the fov would be a chore in a population.

Vegetation aren't eh only use. Though it would be nice to actually use LOD type stuff for distance based crap where you're just wasting resources with physical objects.

[masonspappy]

A trick I've done in the past for distant tree populations is to create a cube object in blender, then put different shape/species of tree on each side. You'll need an opacity mask for each tree. Also, set specularity to 0 in TG to minimize reflectivity.  Now the cube can be used as as a populator object. Since the cube is being randomly rotated in the populator it creates the aspect of numerous tree variation.

While this works ok for distant populations it's not good for closeups.

In attached image below the forest on the far side of the lake was made this was.

[Dune]

Smart!

[Matt]

There isn't an auto-facing option for billboards, but maybe this article is useful for your question about controlling colours:

https://planetside.co.uk/wiki/index.php?title=Population_Colour_Tinting_Techniques

[bobbystahr]

Smart!

echo...and thanks for the trick!

[uuderzo]

@masonspappy thanks for the clever hint!

@Matt thank you for the documentation, I learned a lot of stuff!