troubleshooting recommendations needed for this timewasting lighting problem

I have a huge project with hundreds of objects/textures ect… there is no way I can post it.

But if you can help me try and figure out why this is happening, and perhaps what I could do about it.
I am using 2.69 official. I wish I could say this problem is reproducable, but it seems to have a mind of its own.

I’ll be doing an f12 render and all the lighting will be working fine. It only consists of a sunlamp and 4 point lights in one area. But then I’ll try a rerender after a change and then none of my lights or sun works… the scene is dark, except for the hdri lighting I am using…that hasn’t had any problems. When I have the problem, sometimes I will check and uncheck the lights and the sun…sometimes it works , sometimes not.

I’ll try and rerender a couple times… than all of a sudden…bam… I have lights/sun back again.

Can anyone make suggestions as to why it may be occuring, and if there is anything I can do to try and fix it. It is annoying and a huge timewaster for me.

Are you rendering the same frame every time? Do you have any other apps running in the background? Is your image packed into the file? Are you altering any render layer settings? Are your lights animated? Are you moving lights between layers while having the “this layer only” option enabled? Did you really expect us to be mind readers with the little info that you provided?


Most bugs are quite reproducible and therefore predictable.

One obvious thing I forgot to mention, is that this is using cycles, not BI

Are you rendering the same frame every time

Usually when the problem first happens, I do try rerendering the same frame, because that’s the one I wanted in the first place

Do you have any other apps running in the background

No, just blender

Is your image packed into the file

I have a lots of image textures… none are packed… it’s my working master file…it has over 5 million verts, and uses about 5 gb of memory.

Are you altering any render layer settings

I consistantly have about 7 layers turned on with various objects on different layers. I am not doing any kind of render layers with this file

Are your lights animated

NO, but occasionally I do reposition the angle on the sun

Are you moving lights between layers while having the “this layer only” option enabled

Where is “this layer only” option ? I don’t know what your refering to on this. When the problem first started to occur… I did move the sun and put it on it’s own layer just trying to troubleshoot the problem… that layer is always on when rendering ( camera and viewport icon are enabled, and was only changed that one time.

Most bugs are quite reproducible and therefore predictable.

Sorry I can’t post the blend file it is over 200 mg without textures packed in. What is so strange is when the problem occurs… I can just keep trying a f12 render a couple times… and then all of a sudden the lights appear again.

If there is anything else you, or anyone else wants to ask about to help identify what might be happening, please let me know.
I did try doing a “save as” and gave it a different name, but same thing occurs.

Light Properties buttons>Lamp tab>second check-box on right “This Layer Only”. Lamps with this option enabled will only illuminate objects which reside on the scene layer/layers which that light resides on. All objects in Blender can be set to reside on multiple layers.

You might want to try opening a new .blend file and appending the entire scene to it…sometimes this seems to solve the otherwise unsolvable. Use File>Append or Shift+F1 then navigate to the file and scene.

If you do figure out what sequence of events is causing the trouble and you know it is a bug then you can help by posting to the bug tracker:

Edit: try reproducing the behavior with Blender internal and try it 20 times or so doing the same things you were doing b4. Just scale your output size to 10% of final render size to speed the process along. If you can’t reproduce it in BI but it keeps happening in cycles then you know it’s a cycles bug.

If I append this thing to another file, I need to make sure I capture EVERYTHING. I have hundreds of objects, a crapload of textures,a bunch of bezier curves, lights, environment stuff… and I absolutely would have to know that I can get everything.

What is the best way to append such a giagantic project such as this, and make sure you append everything?

try reproducing the behavior with Blender internal

That unfortunately isn’t going to be possible… there is no way I can convert this file and the tons of materials ect to BI

What about viewport rendering? Does it work every times?
And have you tried with previous versions?


It has failed as well with viewport rendering, but not as often. I haven’t tried a older version of Blender, maybe I should give that a try. I guess I’m wondering now if I have some kind of mildly corrupted file, I’m really not sure what would cause this.

But I would like to also try the appending stuff that was recommended, The project has gotten so big, It’s getting hard for me to track everything. So I would like to get some steps in appending to a new file, but ensuring that I capture everything in the append process.
As mentioned above hundreds of objects / and or group instances, tons of textures, decals, lights and cameras ect. all scattered on about 7 different layers.

How do I keep the objects when appending to be placed on the same layers as the original project?

Are there any linked items in your file? Sometimes if you have linked items that are parented to other linked items from the original file, cycles will hit a loop error trying to figure out which is the real parent. I’ve had this happen with linked items with particle systems where the particles were another linked object. It would constantly reload the path tracing over and over. Check if this is happening in your project.

You convert it to blender internal with a click of the button at the top of the screen. If you’re worried about damaging the file just copy and paste it in a different directory, then rename it. Now open it from the new directory. It cant overwrite your original.

@jblender… there are no linked objects…everything I have brought in has been appended, not linked.