Author Topic: rendering the same scene again after closing Terragen shows different result  (Read 231 times)

Offline ultrasonic

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Hello Terragen Team,

I'd like to know if anyone experienced this before. I just noticed that after doing the following:
1. render scene
2. save scene
3. close terragen
4. open and re-render scene

I did this 3 time to triple check and the results are as follows
73390-0 73392-1 73394-2

Any idea how I can fix this?

Best
Oliver

Offline jaf

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I would try doing a file compare -- use a program like the free WinMerge @ http://winmerge.org/  (if you're using Windows.)  Do the same load, render, save but the second time, save to a different folder.  If the .tgd files compare exactly, then the likely source of the differences are coming from Terragen.
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Offline jaf

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I just tried this on my system and was surprised at the amount of differences between the two test files.
Some differences, like "gui_network_view_position" would appear to be a normal (maybe due
to the OS?)  Others look suspicious, like GI_relative_detail = "2" in the first file and
GI_relative_detail = "1" in the second.

Here's a list of suspicious (to me) differences

file 1                                      file2                                                   note
GI_relative_detail = "2"         GI_relative_detail = "1"
quality = "0.75"                     quality = "0.7529770606"              in Easy Cloud
millions_of_voxels = "30"      millions_of_voxels = "29.99682"    in Easy Cloud


Okay, here's my guess at what's happening.  When the user enter's values (not all values) like 30, it will likely
be something like 29.99682 in the actual program.  However, in this case I didn't enter any values other than
add and easy cloud and hit render (for the first file.)  Then saving the file after everything finished (including
the preview.)  Then an exit  and  restart of Terragen.  Load the first file, render and save (to a different folder)
and then the compare.

« Last Edit: May 15, 2017, 03:58:14 PM by jaf »
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Offline ultrasonic

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thx but I already said that I saved the file - hit render - save that images (not the .tgd file) - closed Terragen - reopened - rendered again - saved to another imagefile - closed terragen WITHOUT SAVING the .tgd again - opened again - rendered again - saved to another imagefile...

The 3 different renders come from the exact same .tgd file!

EDIT: Even with quality varying from "0.75" to "0.7529770606" I would NEVER expect such dramatic lighting changes...this has to be a bug where values are initialized incorrectly I would guess
« Last Edit: May 15, 2017, 04:02:23 PM by ultrasonic »

Offline jaf

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I was just explaining my procedure to test the files -- it backed up that there were differences.
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Offline jaf

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However, I just tried a third file and compared it to the second, and the only difference was
"gui_network_view_position", which changes without rendering (just file load and save.)
I suspect that's normal.

Maybe you can provide the tgd ?
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Offline Ethrieltd

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I don't know if it's related but I had some weird "creep" with Easy Clouds.

I'm not entirely sure how to recreate it, but it's something like this.

1) Create clouds
2) Set quality to 1
3) Move camera/Add object
4) Quality will be <> 1 (usually 1.1868686 or similar)

Something? Anything?

Offline Oshyan

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There are some occasional numerical shift issues. But they should only shift by very small amounts and should not cause such large changes in the look of the render.

What you show in the original set of images looks like it may be a GI problem. Remember that the GI system has some pseudo-random aspects to it, so unless you use a GI cache the GI "solution" (the result and look of the GI) will be a bit different each time. In extreme cases this can cause bigger, more noticeable changes like you show here. Generally you should be able to solve it by increasing GI settings. If you're using v3 clouds here you'll need to use the cloud-specific GI settings, otherwise adjust the standard GI settings.

- Oshyan

Offline ultrasonic

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Thanks everyone for your feedback.

I have attached my .tgd file here * sky_v041.zip

maybe someone could look into it and suggest some more robust GI settings. I just started using terragen and left those settings at their defaults. Any help would be greatly appreciated. We cannot buy the software if we don't get reproduceable results - even if the renders look great!

Thanks in advance
Oli

Offline Oshyan

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I have done a bunch of tests with this scene and it is behaving very oddly. Nothing I have tried seems to fix the issue, yet it's not something I have ever seen anywhere near this bad in terms of issues with inconsistency in the render. I am guessing it may have to do with some of the very unusual settings in for example the hazes, but I'm not sure. I am passing it on to Development to see if they can either find a way to fix it, or identify it as a bug.

- Oshyan

Offline Oshyan

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Oliver, I hope you're still keeping an eye on this thread. We have found a combination of factors that are contributing to the unusually variable results from renders of your scene. Some of those factors are due to extremely high and problematic settings, such as the 5x normal atmosphere glows you have. These extreme values combined with the clouds and high coverage are going to cause issues.

However, another source of problem has been identified that we were able to account for internally, in the render engine. This *may* help stabilize results in your scene and I will be conducting tests on that as soon as possible.

I will update this thread again as soon as I have full findings to share using the latest internal test build of Terragen. If those tests address your issue we will be able to share that build with you, and it will be more widely deployed soon.

- Oshyan

Offline ultrasonic

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Hi Oshyan,

i am still following the thread! Thanks for your investigations. Please keep me posted about new builds that I could test!

thanks in advance
Oliver