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Author Topic: repetition advice?  (Read 2762 times)

simmsimaging

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repetition advice?
« on: February 04, 2012, 10:15:54 PM »
I am having a lot of trouble getting a nice hi-res field of grass that does not show a lot of apparent repetition.

I have gone from using 5 blades of grass, scattered with one FPP object and then that FPP is nested in another to create a larger field (as per your tutorial).

I am actually using two different nested FPP objects that have two different sets of Transform variables, just to create more variety. Then I made copies of the individual blades and made variations on them, so now I'm up to about 20 source blades, scattered into two 1mx1m FPP objects, and those in turn are scattered into a much larger (400-500m) area.  Adding more blades has helped minimally - it just doesn't seem to create enough angle variations or something.

I am using mirroring and quite a bit of rotation at all levels of the FPP objects.  See the result though: the split screen shows two renders of the same patch of grass with different lighting. As soon as the light gets more directional (on the right 1/2) you can see the repetition really jumping out. It kind of looks like a wind blowing from the right to left:



The source geo looks like this:



This is what the Transform looks like for one of the two nested FPP objects - the other is simiilar but with slightly different variables punched in. Mirroring is on for both FPP objects, as well as for the topmost FPP.



Two nested FPP's are using Scattered distribution, topmost is using Dense.

Any idea why it would look so repetitive?

 


jonavark

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Re: repetition advice?
« Reply #1 on: February 04, 2012, 11:36:21 PM »
What is the distribution map? Are you using a map or noise?

simmsimaging

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Re: repetition advice?
« Reply #2 on: February 05, 2012, 02:59:18 AM »
the built-in distribution controls, as noted: scattered and dense. Also tried Full but it really doesn't seem to make much difference once the density is adjusted to even out the volume of blades.

iToo

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Re: repetition advice?
« Reply #3 on: February 06, 2012, 09:47:55 AM »

You would add a scale map to add some variation, but really there are not fixed rules for this issue.

When i have a while, i will create a demo scene.

Carlos Quintero
iToo Software

simmsimaging

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Re: repetition advice?
« Reply #4 on: February 06, 2012, 09:57:53 AM »
The scale is already  being randomly affected with the transform rollout - would a map improve on that for some reason?

I think it's probably more about the geometry. For some reason it just reads really repetitive - I don't think it's a problem with FPP or anything: it's just an approach with the geo or setup or something. I was just looking for advice on how to handle it from those with more experience with this sort of setup :)

I did get it somewhat better by actually removing or reducing some of the more unique looking blades - that might actually be the trick, but still testing.

I'll post if I get it much better.

/b

OH4026

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Re: repetition advice?
« Reply #5 on: February 06, 2012, 02:51:20 PM »
You've proven to  increase significantly the values โ€‹โ€‹of translation?

Regards.

iToo

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Re: repetition advice?
« Reply #6 on: February 06, 2012, 04:45:42 PM »
The scale is already  being randomly affected with the transform rollout - would a map improve on that for some reason?

A noise map would give a clustered look. It may be useful in some cases.

Carlos Quintero
iToo Software

simmsimaging

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Re: repetition advice?
« Reply #7 on: February 07, 2012, 07:29:58 AM »
I will try that. Actually just started adding clustering using the built-in tools but now it won't render at all: keeps crashing Max out. I'm thinking the density might be too high now or something? Not sure, but it killed my workstation with 24GB of RAM and my laptop with 16GB of RAM.

Haven't had a chance to figure it out yet though.

iToo

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Re: repetition advice?
« Reply #8 on: February 07, 2012, 09:55:43 AM »
Or the density is huge, or there is some problem with that scene:

What is the number estimated render items (General->Forest Stats) ?
Are you using collisions ?

I'm working here in a test scene of 400x400m, using four grass patches of 1x1m. This generates a total of 160k items (400x400), with a total memory footprint of 1 Gb. in VRay (very low). It is not finished yet, but i have attached here in case you are interested (Max 2010, VRay 2).

Carlos Quintero
iToo Software

simmsimaging

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Re: repetition advice?
« Reply #9 on: February 07, 2012, 06:20:14 PM »
Thanks for the scene. I rendered it at more like the res I'm working at (so had to swap in a higher res ground map). It has simiilar issues with the visual repetitive pattern:

https://www.evernote.com/shard/s2/sh/4866360a-7b2a-4e5d-9f72-30c20fcd26e3/88b2500301c15c95f7fc96b3aa940af6/res/c585f143-7fa5-405d-9de5-2158f0b41e71/ScreenClip.png

I really think it's a question of really minimizing the obviously bent grass.  Also noticing that your distribution is *way* sparser, so your grass relies heavily on the background map. I was trying to get much more of the density out of the FPP object to improve the realism for the closer to camera areas.

My FPP does not appear to be generating many more meshes though. I am using two nested FPP objects and according the the stats one is creating about 2000 instance, and one about 200.  The FPP they are nested in is creating about 160,000 instances. The poly count is much higher though as my grass has more poly's than yours. Each blade is about 300-400 polys, so the whole set that is being uses as the source for all the grass is about 7000 polys.

I'm guessing it's a poly count issue?

b

iToo

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Re: repetition advice?
« Reply #10 on: February 08, 2012, 09:41:02 AM »

No, there must be another problem. If i increase in my test scene the density on of the grass patches to 100k polys, the memory raises up only to 1.5 Gb and it renders pretty fast.

Are you sure that the main Forest object is in "Automatic" render mode, and not in "Meshes" ?. It seems as it's generating a huge mesh object...

Carlos Quintero
iToo Software

simmsimaging

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Re: repetition advice?
« Reply #11 on: February 08, 2012, 10:04:37 AM »
 I will have to go back to see. I adopted a more sparse approach after looking at yours and it was rendering okay again. I have been bumping up the density without any issues, but haven't been able to run a proper full render as I've been working on other parts of the job all day. I will try another one over night and see how it goes.

/b