Population render quality settings test

[bigben]

Hi All

Decided to remove my confusion on this with some agricultural tests on object quality settings in populations. Two side by side populations of the same object. One set to highest quality, the other to medium quality. I'm not going to tell you which is which... that way you can make up your own mind on the differences 

No soft shadows
Smooth object normals off
Bark texture tiled to 1000pixels/m
Render settings: Detail 1, AA 4, GI 2,2 (I'd prefer higher GI quality but it's good enough for the purpose of this test)
Distances from camera to centre of populations: 400m, 95m, 33m (still rendering)

Extract from log file for each population (irrespective of distance!):
16 objects (0.00214 billion triangles) inserted by Populator "Pop WE04a.obj"

For comparison, from a render using billboard trees:
760439 objects (0.00608 billion triangles) inserted by Populator "Pop 2d card.tgo"

Still to do:
* Render detail/aa settings
* Render time/memory usage comparison for different quality settings
* Minimum distance to replace tree models with billboards

[JohnnyBoy]

The trees on the right appear to have deeper shadows, but I can't tell if that's the placement or the render quality. I would like to see the results with a higher AA setting.

[bigben]

The shadows will vary a bit as I used a default camera (fov = 60°). Next time I'll mix the populations to ease comparison across the scene. As it is I still have to toggle bounding boxes off and on to find which trees are in which group.

For now, this test is just looking at any visible differences as a result of just the Render Quality setting in the population node. I'll look at different Render settings later, and when I get an optimised value for those I might repeat this series. For now it's looking like there is bugger all difference between them with these render settings so I could have saved myself a lot of time with previous projects 

Is the medium quality population on the left or right?

[Harvey Birdman]

I'd say the higher quality ones are on the left.

The difference in lighting angle makes the comparison pretty difficult.

[JohnnyBoy]

Honestly, I can't tell , you may have to wait for the closeup to notice a difference? What's the render times?

[Oshyan]

I think the population quality settings will have a much greater effect at longer distances where the LoD routines come into play more.

- Oshyan

[bigben]

That makes sense from what Matt or Jo told me the last time I was looking at this. I thought I noticed some difference but never got around to a side by side test.  The distant shot is probably getting close to the distance where I can start using billboards so it's quite encouraging that the differences are so subtle at this distance.

I can remember getting trees without leaves in the distance on some older tests, so there may also be a link to the Render detail setting (from memory I had detail turned down a lot for that to happen).

[bigben]

What's the render times?

6hrs 45 min for the large image, the distant render was cropped and was only about 20 minutes. Stopping the closer render now, about 1/3 complete after 6 hrs.

[edit] finally stopped the render. Here's a portion with one tree from each group

[bigben]

OK I think this illustrates the effect of the setting better... Pushed things back to 1km, increased AA to 6 just for the hell of it since it was a smaller render. The visibility of the different settings appears to be dependent in part on the render detail level.  If you have a high detail, you can use low render quality in the populations without losing much detail. ... and if you use low render detail to speed up the rest of your render, you can bump up the quality of the objects so you don't lose too much detail there.

Cropped renders from the same size image as above.

Max and medium quality populations, Render detail 1
[attachimg=#1]

Max and low quality populations, Render detail 1
[attachimg=#2]

Max and low quality populations, Render detail 0.5
[attachimg=#3]

Max and low quality populations, Render detail 0.25
[attachimg=#4]

[JohnnyBoy]

I wanted to try this with a more distant render.

Row 1 has a render detail: of .25, Row 2 has detail: .5, Row 3 detail: 1.
The four columns are the different object settings.

Render times ranged from tens of seconds to almost 40 minutes.

[bigben]

Were the differences in render time for render detail = 1 significant?

[Njen]

You might be interested in a page I created a long time ago. Not that it has much to do with populations, but mroe to do with comparisons of render settings.

http://motionmagnetic.com/a_terragen2/render_examples/render_examples.html

[JohnnyBoy]

Were the differences in render time for render detail = 1 significant?

Yeah, compared to detail .5 they took over three times as long to render.

Here is a full list:

Row1(.25):   1:08s  1:13s  1:47s   3:48s
Row2(.50):   2:14s  2:31s  4:14s   9:25s
Row3(1.0):   7:04s  8:10s  13:34s 38:19s

[bigben]

That's still quite encouraging, because with detail = 1,  the trees don't appear to have degraded that much with low quality in the population and the times are seriously shorter.

[JohnnyBoy]

It's also apparent, that in this situation, there is no reason to use the highest quality for populations - even with low detail settings.