View Full Version : Weird Render Problem At 100%

09-18-2012, 09:41 AM
This is quite strange - very recently my system has been hanging (only way to get it back is to power off and on again) right at the end of a render. When I say right at the end, I mean just at the point where it gets to 100% and the picture is about to be displayed ready for saving.

The scene in question is very polygon & texture heavy but I'm not getting any memory errors like I used to on my old system. Surely if it was a memory problem it wouldn't get anywhere near to 100%?! :confused:

Just wondering if anyone has encountered anything similar before? I'm using version 11.0 64-bit (haven't downloaded the updates), Windows 7 with 16GB RAM - off the top of my head I can't say how many polys are in the scene but even if I get rid of some objects to reduce the amount of polys to less than what it was rendering fine before, it will still hang now.

Also wondering if anyone has any suggestions to get round it?

TIA :thumbsup:

09-18-2012, 10:04 AM
this happens on everyone scene or only with heavy geometry/textures? witch shaders do you use?

09-18-2012, 10:12 AM
Just guessing here: video card issue?

09-18-2012, 08:39 PM
Render as F10, not F9

09-19-2012, 04:06 AM
I rendered a different scene absolutely fine; then I rendered the problem scene at 640x360 and it rendered fine! I cannot render using F10 as the machine will hang at some point. I'm trying to render the scene at 2560x1440 resolution.

The only shader I'm using is Fast Fresnel on a few objects; scene has around 3.2 million polys

09-19-2012, 04:21 AM
how many lights in scene, what a radiosity settings you have?

09-19-2012, 04:46 AM
Settings as follows:

Lights: 3 (2 dome, 1 distant)

Radiosity: Final Gather, Bounces: 1, RPE: 1600, Angular Tolerance: 45deg, Min Pix Spacing: 1.0, Max Pix Spacing: 100.0

Render Settings: Raytrace shadows, transparency, reflection & refraction on, Ray Recursion Limit: 16, Ray Precision: 6.0,

Camera Settings: Perspective Camera, Resolution: HDTV (rendering at 200%), Min. Samples: 32, Max. Samples: 1, Reconstruction Filter: Classic, Sampling Pattern: Classic, Adaptive Sampling on, Threshold: 0.03

09-19-2012, 07:41 AM
Do you mean the other way around for Min/Max Samples? Also, what are the Light and Shading Samples set to in the Render Globals > Render tab?


09-19-2012, 07:47 AM
RPE: 1600 - you can reduce rays to 300-500 painless and play with Multiply settings - 50% ->20%

09-19-2012, 07:59 AM
Do you mean the other way around for Min/Max Samples? Also, what are the Light and Shading Samples set to in the Render Globals > Render tab?


No, Minimum Samples = 32, Max Samples = 1 - I find that the max samples don't do anything whereas the lower the number on the minimum samples the worse the render becomes. Have I got this wrong?

Light and Shade samples are set to 8.

I did try reducing the RPE setting to 600 for a test render which did not prevent a system hang once the render had got to 27% :-( Having said that I left the multiplier setting at 100%.

09-19-2012, 08:13 AM
Then your Adaptive Sampling isn't doing anything. What you are doing is telling LightWave that you want a minimum of 32 samples per pixel (x8 Light Samples x8 Shading Samples). You'll have more success with Light and Shade set to 1, and Max higher than Min. That way, Adaptive Sampling will only antialias areas that need it to the maximum you set in Max Samples. Perhaps that's the reason your renders are hanging? The other possibility I thought of is that you have some sort of post-process, like lens flares, that take place after you render 100% rendering.

PS. I just tried rendering a scene with Min at 32 and Max at 1. You can indeed set those values in Camera Properties, but when you hit Render, the Render Status window shows 32/32.

09-19-2012, 08:38 AM
Thanks for the info. I'll implement your suggestions and see what happens. Still doesn't make sense why it would render at 25% scale though but not at 200%, unless of course rendering at bigger scale takes more computations.

I have no post processes going on at all, certainly no lens flares! All I have that is extra is Fast Fresnel on some of my plant textures, that's it.

09-19-2012, 08:50 AM
I did a quick render of a scene I have here.

Render (https://dl.dropbox.com/u/2807104/forum/render.png)

If I set Min to 32 and Max to 1 and rendered with Light and Surface Samples set to 8 I get a render in 246 seconds (4m6s). Changing it to Min 1 Max 32 and still 8/8 for samples I get 229.5s (3m49s) and setting it to 1/1 I get 223.5s instead.

PS. In all three cases the final image was the same

09-20-2012, 02:31 AM
An update: I changed the settings as suggested by BeeVee and OFF and I managed to render the scene in two goes (left side then right side using render area) without my system hanging. The render times were a collosal improvement from before with minimal loss of quality - I'll need to play around with the RPE setting, maybe raise it a little and play around with the multiplier setting.

When trying to render the full scene the render will complete to 100%, I will click on "continue" and the save dialog box will come up, I'll try to save and BAM, system will hang (can't even do CTRL+ALT+DEL). I then tried rendering using F10; again the render will completely finish (ie the render dialog box will disappear once finished) but as soon as it disappears the system will hang. When I rebooted I noticed the picture had saved to disk though.

I've downloaded the 11.0.3 files so I'll install this in the hope that this fixes it but this just doesn't make sense. How can it finish and then crash???

At least I have learnt a valuable lesson in terms of render optimization so thanks guys :-) even though my original problem still exists :-(

09-20-2012, 03:03 AM
I can only think it's memory despite you having 16 GB. If you hit Ctrl Shift Esc you will get the Windows Task Manager and you will see how much memory you have left. Try using Safe mode for your rendering since it won't load any startup stuff or anything? Do it Adrian, do it! Remember audere est facere! :)

Ooh, the other thing to try is using Screamernet rather than rendering through LightWave at all. Just get Amleto since its setup is so easy you won't be screaming and you can also use it to render a still image in pieces (it will stitch the pieces together too.


09-20-2012, 03:19 AM
Hmmm, load up in safe mode to render? Screamernet sounds good although I'm going to demonstrate my complete ignorance - I've heard of Screamernet but don't know anything about it or how much it costs. Will search Google for some info.... I do like the idea of it stitching the pieces together! However bad news is I don't have much spare cash for another app at the moment....

09-20-2012, 04:16 AM
Screamernet is part of LightWave, you already have it and best of all Amleto is open source and free of charge (http://virtualcoder.co.uk/amleto/). Even if you don't have multiple machines it's still worth having since you won't have the overhead of having to load up LightWave just to render.


09-20-2012, 04:31 AM
Doh! Thanks for that, I feel quite stupid now :-)

09-20-2012, 04:39 AM
Not at all, it seems hard to believe since renderfarm controllers are usually expensive and this one is a) so simple to use and b) free. :)


10-04-2012, 04:13 AM
Turns out I had a faulty hard drive so LightWave not to blame at all!

10-05-2012, 07:35 AM
Adrian (and everyone) - thanks for the graphic and thorough research to help Adrian as well as to help the rest of us better understand so many caveats and tweaks and ways to do things. Definitely useful community. I love it (a lot). :D