Interpolate over n frames creates blotchy results

[dopple152]

Hi - I have been trying to find an answer for this for sometime now and wondered if anyone on here can shed any light on the matter....

I have an interior scene with an animated camera and a lot of animated lights.

I set to Project FG points from positions along path.

Divided camera path by Num. segments 49 (the animation is 1000 frames in total)

I then calculated the fg map creating one per frame.

When I come to render the scene if I leave Interpolate over n frame at 0 the scene is smooth but it will flicker as it will recalculate the fg per frame.

I know the point in in changing the interpolation over n frames to greater number than 0 is to reduce the flicker, however when I set it to 2 for example the render now is extremely splotchy.

this happens when I try rendering from 10 too (so that there are the fg file before the start to allow interpolation)

I hope this makes sense and any help would be massively appreciated!

Thanks

Tim

[Anonymous]

is everything blotchy, or is it the actual lights that flicker, or is it specific areas?

it could be you have to up the image precision or the glossy samples for some of the materials  

[dopple152]

Thanks for the reply!!!

I don't think it is the image precision or glossy samples of the materials as it renders fine with the interpolation set to 0.

Would't the image precision or gloss samples effect the scene exactly the same whether interpolation was set to on or off?

Thanks

[dopple152]

Please see attached....

interpolation set to 0 and set to 2

[Anonymous]

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@dopple152 wrote:

I set to Project FG points from positions along path.

Divided camera path by Num. segments 49 (the animation is 1000 frames in total)

I then calculated the fg map creating one per frame.

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You have the wrong combination of settings. If you Project FG points from positions along path, the you shouls only use a single FG frame.

[dopple152]

Thanks for your reply samab.

As I have an animated camera, I have to Project FG points from positions along path....

but I thought if i have animated lights and objects in the scene as well, I need to use a fgm per frame, not just a single fgm.

I thought a single fgm shouldnt be used if you have animated objects or lights.... (as stated in the mode pull down menu)

Thanks

[dopple152]

however I may be wrong so any input at this stage would be greatly appreciated!!
Thanks
Tim

[Anonymous]

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@dopple152 wrote:

Thanks for your reply samab.

As I have an animated camera, I have to Project FG points from positions along path....

but I thought if i have animated lights and objects in the scene as well, I need to use a fgm per frame, not just a single fgm.

I thought a single fgm shouldnt be used if you have animated objects or lights.... (as stated in the mode pull down menu)

Thanks

---

Correct, don't use a single FG map with animated objects and lights. But also, don't use point along a path with multiple FG maps.

So if you do have moving lights and objects, use camera position, not along the path, and use multiple FG maps, interpolate them if needed to reduce flicker.

[dopple152]

Ah ok,

so even though I have a camera animated along a path, I should not use 'project along camera path' and I should use 'project from camera position (best for stills)'??

Is there a contradiction in there in the terminology?

Thanks again!
Tim

[Anonymous]

What project along path does, if you watch it render, is render a number of sampled frames into a single frame. So rendering multiple frames of this is pointless, because thay are all the same.

'Best for stills', maybe it should read 'Best for stills, and scenes where objects and/or lights move about regardless of whether the camera moves or not'.

Or at least 'Best, but not exclusively, for stills'.

Yes, that can be mis-leading, you have to read to long version in the documentation to understand it properly.

[dopple152]

Hi samab,

Thanks for the explanation!

That does make sense. I will give that a go later and see if it all works how expected now!

Thanks again for your help

T

[dopple152]

Hi ,

I have re-read the auto desk help file (again) on this and it states as follows

'To generate and then use a final gather solution when rendering an animation with moving objects:

This method uses multiple final gather map files and is best for when objects in the scene move during the animation. You can minimize final gather flickering by interpolating among the final gather solutions.

When rendering an animation that contains both a moving camera and moving objects/lights, a special option is available for projecting final-gather points from regular intervals along the camera path; see step 1.

1 If the camera does not move during the animation, skip to step 2. However, if the camera moves through the scene during the animation, on the Final Gather rollout, choose Project Points from Positions Along Camera Path and set Divide Camera Path by Num. Segments to an appropriate value, based on the length of the camera path. Also, if you're using a large number of segments, increase the Initial FG Point Density setting.

2 On the Reuse rollout, set Mode to One File Per Frame.

So this doesn't agree with what you're saying samab... unless im missing something.

hmmm mystery continues....
any thoughts?

Thanks

[mynewcat]

Hello mate - did you find the answer to this one?

I'm in the same boat as you and I'm sitting in the office at 9pm on a Friday night desperately trying to find the answer!

Did you suss it out, if so could you help me out?

Also - if you can't give the whoel answer now, a reply to let me know would be helpful so I can go home!

cheers

[dopple152]

Hi,

Did you work it out in the end?

Sorry i didnt see your post until this morning?

I ended up calculating FG points along camera path and using one file per frame (as the lights were changing colour throughout the animation) this produced the best results. I could then interpolate over a couple of frames to smooth outnte result further.

Hope this helps and its not too late!

[mynewcat]

heers for the reply - but I'm not sure how that would sonve the problem.

Your blitchiness in this case was caused BY interpolating frames... how did you get rid of that blotchiness?

[felix]

I experienced the same with an opening door, best in this case has been to enter "0" at  "Interpolate over N frames".

I noticed with 3dsmax Design 2015 somehow flickering wouldn´t occur like in previous versions.

[JD3D_CGI]

That's no solution, because if you dont interpolate over the frames you're going to get flickering GI - that's the whole point of having  the animation mode.

[felix]

That´s been how I noticed it in previous versions. Though, in a current project with fast movements I had to minimise the Interpolation over frames to "0" otherwise their would have been a dragging lag within the animation. Astonishingly there hasn´t been any flickering anymore. This already worked in several scenes I applied this setting. Might not work everywhere but it certainly worked within the scenes here.

Might be important to mention, I rendered with prerendered singleframe FG maps (naturally) and calculated a new GI map for every single frame on the fly during mainrendering.