Author Topic: population questions  (Read 318 times)

Offline Kevin F

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population questions
« on: November 25, 2017, 01:44:30 PM »
A couple of newbie questions from an oldbie!


What controls or determines the shape of the 3D space that a "free floating" population occupies? There is no "z" depth available to modify yet a degree of depth (height) is produced in the population.


also, is it possible (and if not why not?) to populate onto a population? I've just made a snowflake .obj and can only populate it onto a single instance of a tree. It's not possible to anchor the snowflake pop to a population of trees.
Is this a bug or is it just not possible.


Since populations are generated from a single instance of an object, why can't the single instance be pre-populated?
« Last Edit: November 25, 2017, 03:59:03 PM by Kevin F »

Offline luvsmuzik

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Re: population questions
« Reply #1 on: November 25, 2017, 02:51:36 PM »
You could..group your snowflake obj with your tree obj. out of program..then hope that random rotation and scale settings avoid the copycat look..

I only know simple solutions and if it is a tgo tree, I have no program to import that outside of TG.

Online cyphyr

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Re: population questions
« Reply #2 on: November 25, 2017, 05:04:22 PM »
You can add a plane object and give it a very rough but fine displacement, (Scale 1, Lead-in scale 1, smallest scale 0.001 and displacement of maybe 100 for example) you'll have to experiment for your own needs and set you population to "Sit on object" in the Anchor tab.
Then make the plane object non rendering and non shadow casting.
If you did that with maybe five populations and five planes you could come up with a quite convincing snow storm.

Population on populations has been asked for many times but is not possible at the moment.
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Offline Kevin F

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Re: population questions
« Reply #3 on: November 25, 2017, 05:43:14 PM »
Thanks guys,
@luvsmuzik: thanks but I can't make such a grouped object.




@Richard: the existing free floating option appears to use an invisible plane object, and a convincing snow "shower" can be made by tilting this by 45degrees and looking through it as in:  camera ------>/scene.      where / is the tilted plane.
your idea of multiple layer looks good and I'll give it a try. Thanks.

Offline Oshyan

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Re: population questions
« Reply #4 on: November 26, 2017, 04:04:22 AM »
The height (not Z actually but Y = up in Terragen) of a population is determined by the shape of the object or terrain it's anchored to. If you have an object with one part at 1 meter above ground, and another part at 1000 meters above ground, and you populate on that object, you'll have some instances at 1 meter and some at 1000. If you have a procedurally displaced place that you're using to anchor a population to, your population instance's heights will depend on the total amplitude/height of the displacement.

Populations on populations are not currently possible. Might be added in the future, I don't know what the technical challenges are though.

I'm not sure what you mean by "pre-populating", but as others have said you can certainly bring in an object that has, for example, 100 trees in it (created in another program). It would have a lot of geometry and would not be able to conform to a terrain using the populator, but you could at least populate on it because it's a single object. It's a workaround, not a total solution, but depending on what you want to do it may be effective.

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Offline bobbystahr

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Re: population questions
« Reply #5 on: November 26, 2017, 04:36:42 AM »
Thanks guys,
@luvsmuzik: thanks but I can't make such a grouped object.



Kevin, re: grouped objects what luvsmuzik meant is if you have objects in .obj format and a program that reads them load say 5 variations of a plant, or 5 different plants into that program  and group and save as a single object. I then load that object into TG and save it as a .tgo halving it's size and then when populating with the .tgo restricting the pop to 10-20 maximum slope. works not too bad and is good for variety when you are limited in pops with a free version when I used this method.
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Offline Kevin F

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Re: population questions
« Reply #6 on: November 26, 2017, 08:56:57 AM »
Thanks Oshyan and bobby,your replies makes sense but in my situation where I'm trying to replicate falling snow over a relatively flat terrain, I was hoping there was a method of making a large floating cube of falling snow. The only controls for shape of the area covered available are in X,Z. So what determines the thickness (Y) of the float? If the population follows the shape (heights) of the terrain or of the object anchored to then it's really quite limited.
I might not be explaining this very well, but my population of very small snow flakes (0.5cm to 1.25cm flakes) just gives me a thin plane of flakes all at one height determined by height values in the populator and/or the original snow flake object).


As for pre-populating, I mean if the populator works by making a single instance of an object and placing it at (0,0,0,)? and then using this to make copies in an area determined by the user, why can't an object with a population of other objects anchored to it be some how saved by TG and then used as the single instance of a new population?


I appreciated and understand what you, bobbystahr and luvsmusik say about making the object(s) in another program but just wanted to do it all in TG. :)
« Last Edit: November 26, 2017, 08:58:52 AM by Kevin F »

Online cyphyr

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Re: population questions
« Reply #7 on: November 26, 2017, 03:05:52 PM »
Here is a very quick and dirty setup for a snow fall. I'm sure you can improve on it greatly :)
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Offline Kevin F

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Re: population questions
« Reply #8 on: November 26, 2017, 04:04:23 PM »
Thanks Richard, I'll take a look. Having good results from two 45 degree floating pops at the moment.

Offline bobbystahr

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Re: population questions
« Reply #9 on: November 26, 2017, 06:44:21 PM »
Thanks Richard, I'll take a look. Having good results from two 45 degree floating pops at the moment.

that was my next suggestion...
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Offline Oshyan

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Re: population questions
« Reply #10 on: November 27, 2017, 01:17:07 AM »
Populations are like heightfields: they exist on a contiguous surface, you cannot have a population instance above or below another one (though they can of course overlap, they will not be at different heights). So filling a volume (e.g. cube) with instances is not possible.

The answer to your question about "pre-populating" is the same as for populating on populations: it's just a feature that hasn't been implemented. We have thought about "populations of populations" before, as a way to get truly massive-scale instancing (billions or even trillions of instances), but it has not been developed yet and so far is just a concept.

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Offline Matt

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Re: population questions
« Reply #11 on: November 27, 2017, 05:07:02 PM »
Populations are like heightfields: they exist on a contiguous surface, you cannot have a population instance above or below another one (though they can of course overlap, they will not be at different heights). So filling a volume (e.g. cube) with instances is not possible.

But if the instances are randomly positioned (as they are by default), then you can scatter them through a volume simply by making the height completely random at each point (or change very quickly in space). You can do this with noise functions or with small-scale fractals (a slower way to create noise).

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